RE: Subnet question [7:60711]
OR , you don't have to change the IP , you can simply change the Vlan on the port to work for the IP on the WKST. As long as you have DHCP up and running and you have got vlans configured on your switch , you can move a pc any where , put the port into the correct Vlan , and you will work. I have set up a four story building with 2000 P.C's , haven't had a day's problem :) -Original Message- From: MADMAN [mailto:[EMAIL PROTECTED]] Sent: Thursday, January 09, 2003 7:25 PM To: [EMAIL PROTECTED] Subject: Re: Subnet question [7:60711] don't do anything. If you put a 10.100.1.x host on the 10.100.2.x network it won't work until you do change the IP. Dave Tamhankar, Nitin wrote: This might be a very elementary question for some of you guys but I would appreciate the answer. If an office which has 3 different floors and has Cisco routers and catalyst switches and windows environment. We need to configure it in such a way that each floor is on its own subnet for example floor1 100.10.1.0 floor2 100.10.2.0 floor3 100.10.3.0 Also if a computer which has IP address in subnet 100.10.1.0 is moved from floor 1 to floor 2, it should not communicate with the network unless its IP address is changed to one in 100.10.2.0 subnet. How it can be accomplished? Thank you Nitin [GroupStudy.com removed an attachment of type application/ms-tnef] -- David Madland CCIE# 2016 Sr. Network Engineer Qwest Communications 612-664-3367 You don't make the poor richer by making the rich poorer. --Winston Churchill NOTICE - This message contains privileged and confidential information intended only for the use of the addressee named above. Any review, retransmission, dissemination, copying, disclosure or other use of, or taking of any action in reliance upon, this information by person or entities other than the intended recipient is prohibited. If you have received this message in error, please notify the sender by return email and delete this message. This message should not be copied or used for any purpose other than intended, nor should it be disclosed to any other person. Any views expressed in this message are those of the individual sender, except where the sender specifically states them to be the view of Investec Group, its subsidiaries or associates. The Investec Group is not liable for the security of information sent by e-mail at your request, nor for the proper and complete transmission of the information contained in the communication nor for any delay in its receipt. Please note that the recipient must scan this e-mail and any attached files for viruses and the like. The Investec Group accepts no liability of whatever nature for any loss, liability, damage or expense resulting directly or indirectly from the access of any files which are attached to this message. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=60797t=60711 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Subnet question [7:60711]
I would set up VLAN's keep in mind you need to route between VLAN's. This is done via RSM or router on a stick. -Original Message- From: Tamhankar, Nitin [mailto:[EMAIL PROTECTED]] Sent: Thursday, January 09, 2003 11:40 AM To: [EMAIL PROTECTED] Subject: Subnet question [7:60711] This might be a very elementary question for some of you guys but I would appreciate the answer. If an office which has 3 different floors and has Cisco routers and catalyst switches and windows environment. We need to configure it in such a way that each floor is on its own subnet for example floor1 100.10.1.0 floor2 100.10.2.0 floor3 100.10.3.0 Also if a computer which has IP address in subnet 100.10.1.0 is moved from floor 1 to floor 2, it should not communicate with the network unless its IP address is changed to one in 100.10.2.0 subnet. How it can be accomplished? Thank you Nitin [GroupStudy.com removed an attachment of type application/ms-tnef] Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=60821t=60711 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Subnet question [7:60711]
I would set up VLAN's keep in mind you need to route between VLAN's. This is done via RSM or router on a stick. Daniel Ladrach CCNA, CCNP WorldCom Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=60836t=60711 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Subnet question [7:60711]
Don't forget the Simplicity Principle! :-) I liked MADMAN's answer best. He's a CCIE and it shows. Without some idea of the fellow's topology, we can't recommend VLANs, and, although I know VLANs are extremely popular and the obvious choice for some situations, they add complexity that may not be necessary. And recommending Mobile IP for something as simple as this is definitely overkill. Priscilla Xia Hongbing wrote: One thing I want to mentioned is that Mobile IP can solve your problem. You can move to another place without changing your IP address, but still keep connection. However, you must configure both floor 1 and floor 2 router to support Foreign agent and home agent function. Your computer client also support mobile IP registration. - Original Message - From: Priscilla Oppenheimer To: Sent: Thursday, January 09, 2003 4:58 PM Subject: RE: Subnet question [7:60711] Larry Letterman wrote: thats pris's job hereif she writes enough detailed answers we dont have to buy her books...:) Oh no! By the way, the only nicknames that are supported are Cilla, PO, (and Cil, if you are Chuck.) Nicknames that map to sissified have been deprecated. The preferred name is my canonical name, Priscilla. :-) Larry Letterman Network Engineer San Jose Transport Cisco Systems Inc. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Tamhankar, Nitin Sent: Thursday, January 09, 2003 11:18 AM To: [EMAIL PROTECTED] Subject: RE: Subnet question [7:60711] Thank you very much for taking pains to right such a detailed explanation. Thank you all for your answers they were very helpful. Thanks Nitin -Original Message- From: Priscilla Oppenheimer [mailto:[EMAIL PROTECTED]] Sent: Thursday, January 09, 2003 12:36 PM To: [EMAIL PROTECTED] Subject: RE: Subnet question [7:60711] You may not need virtual LANs. Real LANs solve the problem. :-) This is a classic case of subnetting. With DHCP, the client should get the right address when it broadcasts after it moves, so there's no issue. Leaving DHCP out of the picture, the need to ensure that a moved node can't communicate is met simply by the way IP works. Assume there's a client with this config: address = 100.10.1.100 subnet mask = 255.255.255.0 default gateway = 100.10.1.1 Assume the client is physically sitting on the 100.10.2.0/24 network. When it wants to send to nodes on the 100.10.1.0 network, it will compare its address with the destination address, assume it's on the same subnet, and send an ARP broadcast. The ARP broadcast won't reach the destination though, which is on a different LAN, so it won't work. (Make sure the router isn't configured for Proxy ARP. But even with Proxy ARP, communication won't work. With Proxy ARP, the router could respond on behalf of the destination on the 100.10.1.0 network. However that host wouldn't be able to respond because it would assume that 100.10.1.1 is local.) Assume the client wishes to reach devices on the 100.10.2.0 or 100.10.3.0 network. It will compare its address with the destination address and decide that it's not on the same subnet, so it needs to send to the default gateway. It will send a broadcast for the default gateway, which won't work because 10.10.1.1 is on a different LAN. Once again make sure Proxy ARP is disabled. I'll leave it to the reader to figure out what would happen in this case if Proxy ARP were enabled. :-) The question of VLANs versus real LANs requires more info. How many router ports to you have? Is each router port a subnet? Or do you plan to have multiple subnets out one router port, in which case you need VLANs and inter-VLAN routing on the router. ___ Priscilla Oppenheimer www.troubleshootingnetworks.com www.priscilla.com Nathan Nakao wrote: I'd probably use VLAN's. Conf t Int vlan 101 Int vlan 102 Int vlan 103 Then setup the DHCP to assign IP addresses accordingly. Once that is done. Set the vlans to 101 for first floor, 102 for second floor, and 103 for third floor. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Tamhankar, Nitin Sent: Thursday, January 09, 2003 8:40 AM To: [EMAIL PROTECTED] Subject: Subnet question [7:60711] This might be a very elementary question for some of you guys but I would appreciate the answer. If an office which has 3 different floors and has Cisco routers
RE: Subnet question [7:60711]
I'd probably use VLAN's. Conf t Int vlan 101 Int vlan 102 Int vlan 103 Then setup the DHCP to assign IP addresses accordingly. Once that is done. Set the vlans to 101 for first floor, 102 for second floor, and 103 for third floor. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Tamhankar, Nitin Sent: Thursday, January 09, 2003 8:40 AM To: [EMAIL PROTECTED] Subject: Subnet question [7:60711] This might be a very elementary question for some of you guys but I would appreciate the answer. If an office which has 3 different floors and has Cisco routers and catalyst switches and windows environment. We need to configure it in such a way that each floor is on its own subnet for example floor1 100.10.1.0 floor2 100.10.2.0 floor3 100.10.3.0 Also if a computer which has IP address in subnet 100.10.1.0 is moved from floor 1 to floor 2, it should not communicate with the network unless its IP address is changed to one in 100.10.2.0 subnet. How it can be accomplished? Thank you Nitin [GroupStudy.com removed an attachment of type application/ms-tnef] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=60716t=60711 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Subnet question [7:60711]
don't do anything. If you put a 10.100.1.x host on the 10.100.2.x network it won't work until you do change the IP. Dave Tamhankar, Nitin wrote: This might be a very elementary question for some of you guys but I would appreciate the answer. If an office which has 3 different floors and has Cisco routers and catalyst switches and windows environment. We need to configure it in such a way that each floor is on its own subnet for example floor1 100.10.1.0 floor2 100.10.2.0 floor3 100.10.3.0 Also if a computer which has IP address in subnet 100.10.1.0 is moved from floor 1 to floor 2, it should not communicate with the network unless its IP address is changed to one in 100.10.2.0 subnet. How it can be accomplished? Thank you Nitin [GroupStudy.com removed an attachment of type application/ms-tnef] -- David Madland CCIE# 2016 Sr. Network Engineer Qwest Communications 612-664-3367 You don't make the poor richer by making the rich poorer. --Winston Churchill Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=60717t=60711 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Subnet question [7:60711]
You may not need virtual LANs. Real LANs solve the problem. :-) This is a classic case of subnetting. With DHCP, the client should get the right address when it broadcasts after it moves, so there's no issue. Leaving DHCP out of the picture, the need to ensure that a moved node can't communicate is met simply by the way IP works. Assume there's a client with this config: address = 100.10.1.100 subnet mask = 255.255.255.0 default gateway = 100.10.1.1 Assume the client is physically sitting on the 100.10.2.0/24 network. When it wants to send to nodes on the 100.10.1.0 network, it will compare its address with the destination address, assume it's on the same subnet, and send an ARP broadcast. The ARP broadcast won't reach the destination though, which is on a different LAN, so it won't work. (Make sure the router isn't configured for Proxy ARP. But even with Proxy ARP, communication won't work. With Proxy ARP, the router could respond on behalf of the destination on the 100.10.1.0 network. However that host wouldn't be able to respond because it would assume that 100.10.1.1 is local.) Assume the client wishes to reach devices on the 100.10.2.0 or 100.10.3.0 network. It will compare its address with the destination address and decide that it's not on the same subnet, so it needs to send to the default gateway. It will send a broadcast for the default gateway, which won't work because 10.10.1.1 is on a different LAN. Once again make sure Proxy ARP is disabled. I'll leave it to the reader to figure out what would happen in this case if Proxy ARP were enabled. :-) The question of VLANs versus real LANs requires more info. How many router ports to you have? Is each router port a subnet? Or do you plan to have multiple subnets out one router port, in which case you need VLANs and inter-VLAN routing on the router. ___ Priscilla Oppenheimer www.troubleshootingnetworks.com www.priscilla.com Nathan Nakao wrote: I'd probably use VLAN's. Conf t Int vlan 101 Int vlan 102 Int vlan 103 Then setup the DHCP to assign IP addresses accordingly. Once that is done. Set the vlans to 101 for first floor, 102 for second floor, and 103 for third floor. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Tamhankar, Nitin Sent: Thursday, January 09, 2003 8:40 AM To: [EMAIL PROTECTED] Subject: Subnet question [7:60711] This might be a very elementary question for some of you guys but I would appreciate the answer. If an office which has 3 different floors and has Cisco routers and catalyst switches and windows environment. We need to configure it in such a way that each floor is on its own subnet for example floor1 100.10.1.0 floor2 100.10.2.0 floor3 100.10.3.0 Also if a computer which has IP address in subnet 100.10.1.0 is moved from floor 1 to floor 2, it should not communicate with the network unless its IP address is changed to one in 100.10.2.0 subnet. How it can be accomplished? Thank you Nitin [GroupStudy.com removed an attachment of type application/ms-tnef] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=60724t=60711 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Subnet question [7:60711]
Thank you very much for taking pains to right such a detailed explanation. Thank you all for your answers they were very helpful. Thanks Nitin -Original Message- From: Priscilla Oppenheimer [mailto:[EMAIL PROTECTED]] Sent: Thursday, January 09, 2003 12:36 PM To: [EMAIL PROTECTED] Subject: RE: Subnet question [7:60711] You may not need virtual LANs. Real LANs solve the problem. :-) This is a classic case of subnetting. With DHCP, the client should get the right address when it broadcasts after it moves, so there's no issue. Leaving DHCP out of the picture, the need to ensure that a moved node can't communicate is met simply by the way IP works. Assume there's a client with this config: address = 100.10.1.100 subnet mask = 255.255.255.0 default gateway = 100.10.1.1 Assume the client is physically sitting on the 100.10.2.0/24 network. When it wants to send to nodes on the 100.10.1.0 network, it will compare its address with the destination address, assume it's on the same subnet, and send an ARP broadcast. The ARP broadcast won't reach the destination though, which is on a different LAN, so it won't work. (Make sure the router isn't configured for Proxy ARP. But even with Proxy ARP, communication won't work. With Proxy ARP, the router could respond on behalf of the destination on the 100.10.1.0 network. However that host wouldn't be able to respond because it would assume that 100.10.1.1 is local.) Assume the client wishes to reach devices on the 100.10.2.0 or 100.10.3.0 network. It will compare its address with the destination address and decide that it's not on the same subnet, so it needs to send to the default gateway. It will send a broadcast for the default gateway, which won't work because 10.10.1.1 is on a different LAN. Once again make sure Proxy ARP is disabled. I'll leave it to the reader to figure out what would happen in this case if Proxy ARP were enabled. :-) The question of VLANs versus real LANs requires more info. How many router ports to you have? Is each router port a subnet? Or do you plan to have multiple subnets out one router port, in which case you need VLANs and inter-VLAN routing on the router. ___ Priscilla Oppenheimer www.troubleshootingnetworks.com www.priscilla.com Nathan Nakao wrote: I'd probably use VLAN's. Conf t Int vlan 101 Int vlan 102 Int vlan 103 Then setup the DHCP to assign IP addresses accordingly. Once that is done. Set the vlans to 101 for first floor, 102 for second floor, and 103 for third floor. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Tamhankar, Nitin Sent: Thursday, January 09, 2003 8:40 AM To: [EMAIL PROTECTED] Subject: Subnet question [7:60711] This might be a very elementary question for some of you guys but I would appreciate the answer. If an office which has 3 different floors and has Cisco routers and catalyst switches and windows environment. We need to configure it in such a way that each floor is on its own subnet for example floor1 100.10.1.0 floor2 100.10.2.0 floor3 100.10.3.0 Also if a computer which has IP address in subnet 100.10.1.0 is moved from floor 1 to floor 2, it should not communicate with the network unless its IP address is changed to one in 100.10.2.0 subnet. How it can be accomplished? Thank you Nitin [GroupStudy.com removed an attachment of type application/ms-tnef] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=60728t=60711 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Subnet question [7:60711]
Surely there are a lot of solutions; which I'd do is: Define a different VLAN for each floor. Connect the catalysts in each floor with trunk interfaces (802.1q) Connect a Fast or Giga ethernet interface from a router to one of the switches. You must setup that interface (both on the router an on the switch side) as DOT1Q. On the router you can do it with the following config: -- Note: VLAN 101 - Floor 1 VLAN 102 - Floor 2 VLAN 103 - Floor 3 interface fastethernet 0/0 (for example) full-duplex (Duplex full?) speed 100 no ip address interface fastethernet 0/0.101 encap dot1q 101 ip address 10.100.1.254 255.255.255.0 interface fastethernet 0/0.102 encap dot1q 102 ip address 10.100.2.254 255.255.255.0 interface fastethernet 0/0.103 encap dot1q 103 ip address 10.100.3.254 255.255.255.0 If you tell us which switches are you using (cat or IOS based) I can put you a config for that; assuming they are IOS, it is more or less: --- Switch on floor 1: interface FastEthernet0/1 switchport access vlan 101 switchport mode access duplex full speed 100 interface FastEthernet0/2 switchport access vlan 101 switchport mode access duplex full speed 100 ... ! Trunk to floor 2 interface FastEthernet0/10 switchport mode trunk duplex full speed 100 .. Switch on floor 2: interface FastEthernet0/1 switchport access vlan 102 switchport mode access duplex full speed 100 interface FastEthernet0/2 switchport access vlan 102 switchport mode access duplex full speed 100 ... ! Trunk to floor 1 interface FastEthernet0/10 switchport mode trunk duplex full speed 100 ! Trunk to floor 3 interface FastEthernet0/11 switchport mode trunk duplex full speed 100 Francisco Sedano Informatica Pronet CCIE Student :-) Tamhankar, Nitin Enviado por: [EMAIL PROTECTED] 09/01/2003 17:40 Por favor, responda a Tamhankar, Nitin Para: [EMAIL PROTECTED] cc: Asunto: Subnet question [7:60711] This might be a very elementary question for some of you guys but I would appreciate the answer. If an office which has 3 different floors and has Cisco routers and catalyst switches and windows environment. We need to configure it in such a way that each floor is on its own subnet for example floor1 100.10.1.0 floor2 100.10.2.0 floor3 100.10.3.0 Also if a computer which has IP address in subnet 100.10.1.0 is moved from floor 1 to floor 2, it should not communicate with the network unless its IP address is changed to one in 100.10.2.0 subnet. How it can be accomplished? Thank you Nitin [GroupStudy.com removed an attachment of type application/ms-tnef] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=60754t=60711 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Subnet question [7:60711]
Larry Letterman wrote: thats pris's job hereif she writes enough detailed answers we dont have to buy her books...:) Oh no! By the way, the only nicknames that are supported are Cilla, PO, (and Cil, if you are Chuck.) Nicknames that map to sissified have been deprecated. The preferred name is my canonical name, Priscilla. :-) Larry Letterman Network Engineer San Jose Transport Cisco Systems Inc. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Tamhankar, Nitin Sent: Thursday, January 09, 2003 11:18 AM To: [EMAIL PROTECTED] Subject: RE: Subnet question [7:60711] Thank you very much for taking pains to right such a detailed explanation. Thank you all for your answers they were very helpful. Thanks Nitin -Original Message- From: Priscilla Oppenheimer [mailto:[EMAIL PROTECTED]] Sent: Thursday, January 09, 2003 12:36 PM To: [EMAIL PROTECTED] Subject: RE: Subnet question [7:60711] You may not need virtual LANs. Real LANs solve the problem. :-) This is a classic case of subnetting. With DHCP, the client should get the right address when it broadcasts after it moves, so there's no issue. Leaving DHCP out of the picture, the need to ensure that a moved node can't communicate is met simply by the way IP works. Assume there's a client with this config: address = 100.10.1.100 subnet mask = 255.255.255.0 default gateway = 100.10.1.1 Assume the client is physically sitting on the 100.10.2.0/24 network. When it wants to send to nodes on the 100.10.1.0 network, it will compare its address with the destination address, assume it's on the same subnet, and send an ARP broadcast. The ARP broadcast won't reach the destination though, which is on a different LAN, so it won't work. (Make sure the router isn't configured for Proxy ARP. But even with Proxy ARP, communication won't work. With Proxy ARP, the router could respond on behalf of the destination on the 100.10.1.0 network. However that host wouldn't be able to respond because it would assume that 100.10.1.1 is local.) Assume the client wishes to reach devices on the 100.10.2.0 or 100.10.3.0 network. It will compare its address with the destination address and decide that it's not on the same subnet, so it needs to send to the default gateway. It will send a broadcast for the default gateway, which won't work because 10.10.1.1 is on a different LAN. Once again make sure Proxy ARP is disabled. I'll leave it to the reader to figure out what would happen in this case if Proxy ARP were enabled. :-) The question of VLANs versus real LANs requires more info. How many router ports to you have? Is each router port a subnet? Or do you plan to have multiple subnets out one router port, in which case you need VLANs and inter-VLAN routing on the router. ___ Priscilla Oppenheimer www.troubleshootingnetworks.com www.priscilla.com Nathan Nakao wrote: I'd probably use VLAN's. Conf t Int vlan 101 Int vlan 102 Int vlan 103 Then setup the DHCP to assign IP addresses accordingly. Once that is done. Set the vlans to 101 for first floor, 102 for second floor, and 103 for third floor. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Tamhankar, Nitin Sent: Thursday, January 09, 2003 8:40 AM To: [EMAIL PROTECTED] Subject: Subnet question [7:60711] This might be a very elementary question for some of you guys but I would appreciate the answer. If an office which has 3 different floors and has Cisco routers and catalyst switches and windows environment. We need to configure it in such a way that each floor is on its own subnet for example floor1 100.10.1.0 floor2 100.10.2.0 floor3 100.10.3.0 Also if a computer which has IP address in subnet 100.10.1.0 is moved from floor 1 to floor 2, it should not communicate with the network unless its IP address is changed to one in 100.10.2.0 subnet. How it can be accomplished? Thank you Nitin [GroupStudy.com removed an attachment of type application/ms-tnef] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=60774t=60711 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Subnet question [7:60711]
I'll open a TAC case to have other names supported... Larry Letterman Network Engineer San Jose Transport Cisco Systems Inc. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] Sent: Thursday, January 09, 2003 4:58 PM To: [EMAIL PROTECTED] Subject: RE: Subnet question [7:60711] Larry Letterman wrote: thats pris's job hereif she writes enough detailed answers we dont have to buy her books...:) Oh no! By the way, the only nicknames that are supported are Cilla, PO, (and Cil, if you are Chuck.) Nicknames that map to sissified have been deprecated. The preferred name is my canonical name, Priscilla. :-) Larry Letterman Network Engineer San Jose Transport Cisco Systems Inc. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Tamhankar, Nitin Sent: Thursday, January 09, 2003 11:18 AM To: [EMAIL PROTECTED] Subject: RE: Subnet question [7:60711] Thank you very much for taking pains to right such a detailed explanation. Thank you all for your answers they were very helpful. Thanks Nitin -Original Message- From: Priscilla Oppenheimer [mailto:[EMAIL PROTECTED]] Sent: Thursday, January 09, 2003 12:36 PM To: [EMAIL PROTECTED] Subject: RE: Subnet question [7:60711] You may not need virtual LANs. Real LANs solve the problem. :-) This is a classic case of subnetting. With DHCP, the client should get the right address when it broadcasts after it moves, so there's no issue. Leaving DHCP out of the picture, the need to ensure that a moved node can't communicate is met simply by the way IP works. Assume there's a client with this config: address = 100.10.1.100 subnet mask = 255.255.255.0 default gateway = 100.10.1.1 Assume the client is physically sitting on the 100.10.2.0/24 network. When it wants to send to nodes on the 100.10.1.0 network, it will compare its address with the destination address, assume it's on the same subnet, and send an ARP broadcast. The ARP broadcast won't reach the destination though, which is on a different LAN, so it won't work. (Make sure the router isn't configured for Proxy ARP. But even with Proxy ARP, communication won't work. With Proxy ARP, the router could respond on behalf of the destination on the 100.10.1.0 network. However that host wouldn't be able to respond because it would assume that 100.10.1.1 is local.) Assume the client wishes to reach devices on the 100.10.2.0 or 100.10.3.0 network. It will compare its address with the destination address and decide that it's not on the same subnet, so it needs to send to the default gateway. It will send a broadcast for the default gateway, which won't work because 10.10.1.1 is on a different LAN. Once again make sure Proxy ARP is disabled. I'll leave it to the reader to figure out what would happen in this case if Proxy ARP were enabled. :-) The question of VLANs versus real LANs requires more info. How many router ports to you have? Is each router port a subnet? Or do you plan to have multiple subnets out one router port, in which case you need VLANs and inter-VLAN routing on the router. ___ Priscilla Oppenheimer www.troubleshootingnetworks.com www.priscilla.com Nathan Nakao wrote: I'd probably use VLAN's. Conf t Int vlan 101 Int vlan 102 Int vlan 103 Then setup the DHCP to assign IP addresses accordingly. Once that is done. Set the vlans to 101 for first floor, 102 for second floor, and 103 for third floor. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Tamhankar, Nitin Sent: Thursday, January 09, 2003 8:40 AM To: [EMAIL PROTECTED] Subject: Subnet question [7:60711] This might be a very elementary question for some of you guys but I would appreciate the answer. If an office which has 3 different floors and has Cisco routers and catalyst switches and windows environment. We need to configure it in such a way that each floor is on its own subnet for example floor1 100.10.1.0 floor2 100.10.2.0 floor3 100.10.3.0 Also if a computer which has IP address in subnet 100.10.1.0 is moved from floor 1 to floor 2, it should not communicate with the network unless its IP address is changed to one in 100.10.2.0 subnet. How it can be accomplished? Thank you Nitin [GroupStudy.com removed an attachment of type application/ms-tnef] Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=60781t=60711 -- FAQ, list archives, and subscription info
Re: Subnet question [7:60711]
One thing I want to mentioned is that Mobile IP can solve your problem. You can move to another place without changing your IP address, but still keep connection. However, you must configure both floor 1 and floor 2 router to support Foreign agent and home agent function. Your computer client also support mobile IP registration. - Original Message - From: Priscilla Oppenheimer To: Sent: Thursday, January 09, 2003 4:58 PM Subject: RE: Subnet question [7:60711] Larry Letterman wrote: thats pris's job hereif she writes enough detailed answers we dont have to buy her books...:) Oh no! By the way, the only nicknames that are supported are Cilla, PO, (and Cil, if you are Chuck.) Nicknames that map to sissified have been deprecated. The preferred name is my canonical name, Priscilla. :-) Larry Letterman Network Engineer San Jose Transport Cisco Systems Inc. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Tamhankar, Nitin Sent: Thursday, January 09, 2003 11:18 AM To: [EMAIL PROTECTED] Subject: RE: Subnet question [7:60711] Thank you very much for taking pains to right such a detailed explanation. Thank you all for your answers they were very helpful. Thanks Nitin -Original Message- From: Priscilla Oppenheimer [mailto:[EMAIL PROTECTED]] Sent: Thursday, January 09, 2003 12:36 PM To: [EMAIL PROTECTED] Subject: RE: Subnet question [7:60711] You may not need virtual LANs. Real LANs solve the problem. :-) This is a classic case of subnetting. With DHCP, the client should get the right address when it broadcasts after it moves, so there's no issue. Leaving DHCP out of the picture, the need to ensure that a moved node can't communicate is met simply by the way IP works. Assume there's a client with this config: address = 100.10.1.100 subnet mask = 255.255.255.0 default gateway = 100.10.1.1 Assume the client is physically sitting on the 100.10.2.0/24 network. When it wants to send to nodes on the 100.10.1.0 network, it will compare its address with the destination address, assume it's on the same subnet, and send an ARP broadcast. The ARP broadcast won't reach the destination though, which is on a different LAN, so it won't work. (Make sure the router isn't configured for Proxy ARP. But even with Proxy ARP, communication won't work. With Proxy ARP, the router could respond on behalf of the destination on the 100.10.1.0 network. However that host wouldn't be able to respond because it would assume that 100.10.1.1 is local.) Assume the client wishes to reach devices on the 100.10.2.0 or 100.10.3.0 network. It will compare its address with the destination address and decide that it's not on the same subnet, so it needs to send to the default gateway. It will send a broadcast for the default gateway, which won't work because 10.10.1.1 is on a different LAN. Once again make sure Proxy ARP is disabled. I'll leave it to the reader to figure out what would happen in this case if Proxy ARP were enabled. :-) The question of VLANs versus real LANs requires more info. How many router ports to you have? Is each router port a subnet? Or do you plan to have multiple subnets out one router port, in which case you need VLANs and inter-VLAN routing on the router. ___ Priscilla Oppenheimer www.troubleshootingnetworks.com www.priscilla.com Nathan Nakao wrote: I'd probably use VLAN's. Conf t Int vlan 101 Int vlan 102 Int vlan 103 Then setup the DHCP to assign IP addresses accordingly. Once that is done. Set the vlans to 101 for first floor, 102 for second floor, and 103 for third floor. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Tamhankar, Nitin Sent: Thursday, January 09, 2003 8:40 AM To: [EMAIL PROTECTED] Subject: Subnet question [7:60711] This might be a very elementary question for some of you guys but I would appreciate the answer. If an office which has 3 different floors and has Cisco routers and catalyst switches and windows environment. We need to configure it in such a way that each floor is on its own subnet for example floor1 100.10.1.0 floor2 100.10.2.0 floor3 100.10.3.0 Also if a computer which has IP address in subnet 100.10.1.0 is moved from floor 1 to floor 2, it should not communicate with the network unless its IP address is changed to one in 100.10.2.0 subnet. How it can be accomplished? Thank you Nitin [GroupStudy.com removed an attachment of type application/ms-tnef] Message
RE: Subnet Question
If you have the IP address 198.144.163.1 / 25, the scope you have assigned is from 198.144.163.0 through 198.144.163.127. This is 1 network with 128 (126 usable) hosts. You can now change the subnet mask to 255.255.255.192, which changes your situation to two subnetworks with 64 (62 usable) hosts on each: 198.144.163.0 Network #1 198.144.163.1 thruHosts on network #1 198.144.163.62 198.144.163.63 Network #1 broadcast 198.144.163.64 Network #2 198.144.163.65 thruHosts on network #2 198.144.163.126 198.144.163.127 Network #2 broadcast Hth, Ole Ole Drews Jensen Systems Network Manager CCNA, MCSE, MCP+I RWR Enterprises, Inc. [EMAIL PROTECTED] http://www.CiscoKing.com NEED A JOB ??? http://www.oledrews.com/job -Original Message- From: Chcuk Murduck [mailto:[EMAIL PROTECTED]] Sent: Wednesday, February 07, 2001 11:37 AM To: [EMAIL PROTECTED] Subject: Subnet Question I have a class assigned for example: 198.144.163.1 mask 255.255.255.128 how do I subnet that to 2 networks. __ Do You Yahoo!? Yahoo! Auctions - Buy the things you want at great prices. http://auctions.yahoo.com/ _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Subnet Question
Hi, With a 26 bit subnet mask (255.255.255.192) 198.144.163.1/26 and 198.144.163.64/26 That will give you hosts from 1 - 62 65 - 126 -Original Message- From: Chcuk Murduck [mailto:[EMAIL PROTECTED]] Sent: 7. febrúar 2001 17:37 To: [EMAIL PROTECTED] Subject: Subnet Question I have a class assigned for example: 198.144.163.1 mask 255.255.255.128 how do I subnet that to 2 networks. __ Do You Yahoo!? Yahoo! Auctions - Buy the things you want at great prices. http://auctions.yahoo.com/ _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Subnet Question
Use a mask of 198.144.163.1/26 (255.255.255.192). Assuming ip subnet-zero is enabled, your networks would be 198.144.163.0, with hosts from .1-.62, and 198.144.163.64, with hosts .65-.126. Brant I. Stevens Internetwork Solutions Engineer Thrupoint, Inc. 545 Fifth Avenue, 14th Floor New York, NY. 10017 646-562-6540 -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Chcuk Murduck Sent: Wednesday, February 07, 2001 12:37 PM To: [EMAIL PROTECTED] Subject: Subnet Question I have a class assigned for example: 198.144.163.1 mask 255.255.255.128 how do I subnet that to 2 networks. __ Do You Yahoo!? Yahoo! Auctions - Buy the things you want at great prices. http://auctions.yahoo.com/ _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Subnet Question
To expand on Johns suggestion, you might also try visiting www.learntosubnet.com and/or downloading Chuck Sumeria's White Paper, "Understanding IP Addressing: Everything You Ever Wanted To Know", at http://www.3com.com/nsc/501302s.html Tom Lisa, Instructor, CCNA, CCAI Community College of Southern Nevada Cisco Regional Networking Academy John Neiberger wrote: I have a class assigned for example: 198.144.163.1 mask 255.255.255.128 how do I subnet that to 2 networks. First, let's look at what you have, 198.144.163.1/25. That gives you 126 usable addresses, 198.144.163.1-126. Now, you want to further divide that into two subnets of 62 usable addresses each. To do this, simply add another bit to the subnet mask. This will give you the following: 198.144.163.0/26 and 198.144.163.64/26 Your usable address range is 1-62 and 65-126. This is because you can't use the .0, .63, .64, and .127 addresses. There are a LOT of threads in the archives about subnetting. You should read through those to get some really good insight into this process. HTH, John Find the best deals on the web at AltaVista Shopping! http://www.shopping.altavista.com _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Subnet question
My contrarian $.02 :) Typically the first and last subnet are not used, This might be true, but toss out 176 and 191, is a non-sequitur :) The 0 and -1 subnet restriction only apply to classful considerations. We're already out of classful thinking here, because we were given a non-/16 block (a /20) out of the Class B network, 172.16.0.0, and are extending the prefix 4 bits to /24. The only subnet addresses that would be considered problematic in our general area would be 172.16.0.0/24 and 172.16.255.0/24 (classful subnets 0 and -1). Of course, neither of those prefixes fall within the block that we were given, so it's not *our* problem :) this leaves 177 through 190, each with a 24 bit mask. Thus, *all* "subnets" 172.16.[176-191].0/24 are valid. I.e., no host or router would object to being given an address 172.16.176.1/24 or 172.16.191.1/24 and 172.16.191.255/24 would not be an all-subnets broadcast (just a simple directed broadcast). Thus, if additional choices had been: G) 172.16.191.0/24 H) 172.16.176.0/24 Then the answer would have been C, F, G, H - Tks | mailto:[EMAIL PROTECTED] BV | mailto:[EMAIL PROTECTED] Sr. Technical Consultant, SBM, A Gates/Arrow Co. Vox 770-623-3430 11455 Lakefield Dr. Fax 770-623-3429 Duluth, GA 30097-1511 = -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Ed Moss Sent: Saturday, January 27, 2001 10:50 PM To: [EMAIL PROTECTED] Subject: Re: Subnet question The 20 bit prefix extends four bits into the third octet (176). 176 in binary is 1011, so with the mask the address ends at 1011. You want to use the next four bits for subnetting (last four 0's) This gives the range of 1011 (176) through 1011 (191) providing 16 subnets with 256 addresses in each subnet. Typically the first and last subnet are not used, toss out 176 and 191, this leaves 177 through 190, each with a 24 bit mask. (We started with 20 bits, and we added four bits for our own subnets). Looking at the possible answers, the following fall in this range. C) 172.16.183.0/24 F) 172.16.190.0/24 Ed ORIGINAL: Can anyone please explain to me how to derive the answer of this question? A company has been assigned a subnet of 172.16.176.0/20, and wants the next four available bits to create 14 subents, each containing an equal number of hosts. Which of the following could represent one of these subnets? A) 172.16.255.0/24 B) 172.16.193.0/24 C) 172.16.183.0/24 D) 172.16.16.0/24 E) 172.16.0.0/24 F) 172.16.190.0/24 Answer is C and F _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Subnet question
The 20 bit prefix extends four bits into the third octet (176). 176 in binary is 1011, so with the mask the address ends at 1011. You want to use the next four bits for subnetting (last four 0's) This gives the range of 1011 (176) through 1011 (191) providing 16 subnets with 256 addresses in each subnet. Typically the first and last subnet are not used, toss out 176 and 191, this leaves 177 through 190, each with a 24 bit mask. (We started with 20 bits, and we added four bits for our own subnets). Looking at the possible answers, the following fall in this range. C) 172.16.183.0/24 F) 172.16.190.0/24 Ed _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Subnet question
Correct. You need 14 subnets, a block of 16. Therefore your third octet will be 176-191. "Hunt Lee" [EMAIL PROTECTED] wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Can anyone please explain to me how to derive the answer of this question? A company has been assigned a subnet of 172.16.176.0/20, and wants the next four available bits to create 14 subents, each containing an equal number of hosts. Which of the following could represent one of these subnets? A) 172.16.255.0/24 B) 172.16.193.0/24 C) 172.16.183.0/24 D) 172.16.16.0/24 E) 172.16.0.0/24 F) 172.16.190.0/24 Answer is C and F Regards, Hunt Lee IP Solution Analyst Cable and Wireless (Sydney) _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Subnet Question
It is true in regard of wild-cards. -Original Message- From: Albert Ip [mailto:[EMAIL PROTECTED]] Sent: ??? ? 03 ?? 2000 19:14 To: 'Chuck Larrieu'; Aaron Moreau-Cook; [EMAIL PROTECTED] Subject: RE: Subnet Question Chuck, Just tried it on a 3662 with IOS 12.1T and it didn't work. Rotuer(config-if)#ip address 10.1.1.1 0.255.255.0 Bad mask 0x00 for address 10.1.1.1 Too bad, it would had made a interesting trouble-shooting lab. Albert -Original Message- From: Chuck Larrieu [mailto:[EMAIL PROTECTED]] Sent: Sunday, September 03, 2000 3:06 AM To: Aaron Moreau-Cook; [EMAIL PROTECTED] Subject: RE: Subnet Question I hate questions like this. Can, May, Always, Never. RFC 1812 strongly discourages this practice. On the other hand, the world won't end if you do. You may even create a permanent income for yourself by setting up your network like this. ;- All the TCP stacks I have worked with allow this on the host side. It occurs to me I've never tried this on a Cisco router, even after the long discussion on the topic a few months ago. Next time I'm in the routers, I'll see what happens and report. Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Aaron Moreau-Cook Sent: Saturday, September 02, 2000 5:48 PM To: [EMAIL PROTECTED] Subject:Subnet Question Question taken from the CCNA Exam Cram book by Walters, Rees, and Coe. A subnet mask can have a value of 0.255.255.0 A) True B) False The Cisco answer would dictate that it is false, and in all functionality it is true. Hypothetically though it could be true, I rememeber this discusion a while ago, but I'm looking to see if I am smoking the proverbial crack. Thanks all! Aaron Moreau-Cook Finally taking his CCNA test this coming Friday ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] This email was scanned using ESPG @ PubliCom Haifa. ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Subnet Question
Original Message Follows From: Albert Ip [EMAIL PROTECTED] Reply-To: Albert Ip [EMAIL PROTECTED] To: "'Chuck Larrieu'" [EMAIL PROTECTED],Aaron Moreau-Cook [EMAIL PROTECTED], [EMAIL PROTECTED] Subject: RE: Subnet Question Date: Sun, 3 Sep 2000 19:14:11 -0700 Chuck, Just tried it on a 3662 with IOS 12.1T and it didn't work. Rotuer(config-if)#ip address 10.1.1.1 0.255.255.0 Bad mask 0x00 for address 10.1.1.1 Too bad, it would had made a interesting trouble-shooting lab. Albert - Hi Albert, I'm familiar with Classfull, Classless Ip addressing, but how would a person go about symplifing one of these unusual masks to an address i.e.- 10.1.1.1/16 ?The ones are right, BUT, where would someone know WHICH octets, you were referring to? Would you just have to type the full address and mask. If they don't work anyway, this is a null point. Thanks Dale CCNA? _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Share information about yourself, create your own public profile at http://profiles.msn.com. ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Subnet Question
OK, I've tried it on a router with 12.1.1 and same results. None of these wacky subnets allowed. Windows 98 still permits this kind of stuff. How about Win2K? Any of you folks want to report if Microsoft is compliant yet? BTW, a quick glance through the RFC reveals that Unix boxes ( mentioned by name, but applies to all OS's ) with a single NIC should not have routing turned on as a matter of compliance. RFC 1812 states specifically that The bit positions containing this extended network number have historically been indicated by a 32-bit mask called the subnet mask. The bits SHOULD be contiguous and fall between the and the fields. More up to date protocols do not refer to a subnet mask, but to a prefix length; the "prefix" portion of an address is that which would be selected by a subnet mask whose most significant bits are all ones and the rest are zeroes. The length of the prefix equals the number of ones in the subnet mask. This document assumes that all subnet masks are expressible as prefix lengths. And Architecturally correct subnet masks are capable of being represented using the prefix length description. They comprise that subset of all possible bits patterns that have a contiguous string of ones at the more significant end, a contiguous string of zeros at the less significant end, and no intervening bits. Lastly Routers SHOULD always treat a route as a network prefix, and SHOULD reject configuration and routing information inconsistent with that model. The word SHOULD in RFC land is pretty strong. Therefore a compliant router will not accept a wacky mask. I presume this includes 3Com, Nortel, and Lucent as well, if anyone wants to verify with those vendors. To get back to the original question then, the answer is FALSE I gotta remember to unlearn all the bad things I learned as a Windows network administrator :- Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Dale Cantrell Sent: Monday, September 04, 2000 5:27 AM To: [EMAIL PROTECTED] Subject: RE: Subnet Question Original Message Follows From: Albert Ip [EMAIL PROTECTED] Reply-To: Albert Ip [EMAIL PROTECTED] To: "'Chuck Larrieu'" [EMAIL PROTECTED],Aaron Moreau-Cook [EMAIL PROTECTED], [EMAIL PROTECTED] Subject: RE: Subnet Question Date: Sun, 3 Sep 2000 19:14:11 -0700 Chuck, Just tried it on a 3662 with IOS 12.1T and it didn't work. Rotuer(config-if)#ip address 10.1.1.1 0.255.255.0 Bad mask 0x00 for address 10.1.1.1 Too bad, it would had made a interesting trouble-shooting lab. Albert - Hi Albert, I'm familiar with Classfull, Classless Ip addressing, but how would a person go about symplifing one of these unusual masks to an address i.e.- 10.1.1.1/16 ?The ones are right, BUT, where would someone know WHICH octets, you were referring to? Would you just have to type the full address and mask. If they don't work anyway, this is a null point. Thanks Dale CCNA? _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Share information about yourself, create your own public profile at http://profiles.msn.com. ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Subnet Question
Yes, but a subnet mask and a wildcard mask are two entirely different things, with two entirely different functions. A subnet mask determines which portion of an IP address is the network portion, and which portion is the host portion. A wildcard mask merely indicates which IP addresses match a particular addressing requirement. Just to rant a teeny bit, it is unfortunate that in a number of the study guides, wildcard masks are presented and treated as if they of necessity are related to subnet masks. I.e. as an "inverse" of the subnet mask. So if I want to filter a network with an access list I use the "inverse" mask, or if I want to place a network into the OSPF process, I use the "inverse" mask. While I appreciate the difficulty of properly explaining the concepts, and I particularly appreciate the difficulty most of us have in understanding and internalizing binary math, the fact remains that the things implied in the books and presentations I have read are wrong. For example, in the statement Access-list 1 permit 209.100.100.64 0.0.0.63 All you are doing is permitting hosts with addresses in the range of 209.100.100.64 through 209.100.100.127 You may make assumptions about the subnet mask associated with 209.100.100.64, but you might be wrong. That access-list is valid, and matches that range of hosts, whether the subnet mask is 255.255.255.0, 255.255.255.192, 255.255.0.0, 255.0.0.0, or 255.248.0.0 for that matter. The mask is merely the means the router CPU uses to easily match bits, using Boolean logic. Well, enough ranting. Got things to do and wives to please. Enjoy the rest of this deliciously long weekend. Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] Sent: Monday, September 04, 2000 1:53 AM To: [EMAIL PROTECTED]; [EMAIL PROTECTED]; [EMAIL PROTECTED]; [EMAIL PROTECTED] Subject:RE: Subnet Question It is true in regard of wild-cards. -Original Message- From: Albert Ip [mailto:[EMAIL PROTECTED]] Sent: ??? ? 03 ?? 2000 19:14 To: 'Chuck Larrieu'; Aaron Moreau-Cook; [EMAIL PROTECTED] Subject: RE: Subnet Question Chuck, Just tried it on a 3662 with IOS 12.1T and it didn't work. Rotuer(config-if)#ip address 10.1.1.1 0.255.255.0 Bad mask 0x00 for address 10.1.1.1 Too bad, it would had made a interesting trouble-shooting lab. Albert -Original Message- From: Chuck Larrieu [mailto:[EMAIL PROTECTED]] Sent: Sunday, September 03, 2000 3:06 AM To: Aaron Moreau-Cook; [EMAIL PROTECTED] Subject: RE: Subnet Question I hate questions like this. Can, May, Always, Never. RFC 1812 strongly discourages this practice. On the other hand, the world won't end if you do. You may even create a permanent income for yourself by setting up your network like this. ;- All the TCP stacks I have worked with allow this on the host side. It occurs to me I've never tried this on a Cisco router, even after the long discussion on the topic a few months ago. Next time I'm in the routers, I'll see what happens and report. Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Aaron Moreau-Cook Sent: Saturday, September 02, 2000 5:48 PM To: [EMAIL PROTECTED] Subject:Subnet Question Question taken from the CCNA Exam Cram book by Walters, Rees, and Coe. A subnet mask can have a value of 0.255.255.0 A) True B) False The Cisco answer would dictate that it is false, and in all functionality it is true. Hypothetically though it could be true, I rememeber this discusion a while ago, but I'm looking to see if I am smoking the proverbial crack. Thanks all! Aaron Moreau-Cook Finally taking his CCNA test this coming Friday ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] This email was scanned using ESPG @ PubliCom Haifa. ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Subnet Question
Chuck wrote... [Lots snipped] Well, enough ranting. Got things to do and wives to please. Enjoy the rest of this deliciously long weekend. Chuck Sorry, I can't resist asking... how many wives is that, and are they all yours??? And slightly more on track, 11.2(17) on a 4700 and 2514 won't accept 'non standard' subnet masks either. Anyone got any earlier IOS versions to try - did IOS *ever* accept dodgy masks? We've finally got rid of the last of our 10.3 dinosaurs so I can't check that :-) JMcL ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Subnet Question
Theoretically you could do it, but everyone who's ever attempted it had been taken out and bludgeoned to death by their coworkers, so in practice the answer would be B) False. ""Aaron Moreau-Cook"" [EMAIL PROTECTED] wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Question taken from the CCNA Exam Cram book by Walters, Rees, and Coe. A subnet mask can have a value of 0.255.255.0 A) True B) False The Cisco answer would dictate that it is false, and in all functionality it is true. Hypothetically though it could be true, I rememeber this discusion a while ago, but I'm looking to see if I am smoking the proverbial crack. Thanks all! Aaron Moreau-Cook Finally taking his CCNA test this coming Friday ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Subnet Question
I hate questions like this. Can, May, Always, Never. RFC 1812 strongly discourages this practice. On the other hand, the world won't end if you do. You may even create a permanent income for yourself by setting up your network like this. ;- All the TCP stacks I have worked with allow this on the host side. It occurs to me I've never tried this on a Cisco router, even after the long discussion on the topic a few months ago. Next time I'm in the routers, I'll see what happens and report. Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Aaron Moreau-Cook Sent: Saturday, September 02, 2000 5:48 PM To: [EMAIL PROTECTED] Subject:Subnet Question Question taken from the CCNA Exam Cram book by Walters, Rees, and Coe. A subnet mask can have a value of 0.255.255.0 A) True B) False The Cisco answer would dictate that it is false, and in all functionality it is true. Hypothetically though it could be true, I rememeber this discusion a while ago, but I'm looking to see if I am smoking the proverbial crack. Thanks all! Aaron Moreau-Cook Finally taking his CCNA test this coming Friday ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Subnet Question
The answer to the question as stated would be false, but - you *can* use discontiguous masks in access lists, which can be a pretty handy feature sometimes. Sincerely, Bradley J. Wilson CCNA, CCDA, MCSE, CCSE, CNX-A, MCT, CTT - Original Message - From: Aaron Moreau-Cook To: [EMAIL PROTECTED] Sent: Saturday, September 02, 2000 8:47 PM Subject: Subnet Question Question taken from the CCNA Exam Cram book by Walters, Rees, and Coe. A subnet mask can have a value of 0.255.255.0 A) True B) False The Cisco answer would dictate that it is false, and in all functionality it is true. Hypothetically though it could be true, I rememeber this discusion a while ago, but I'm looking to see if I am smoking the proverbial crack. Thanks all! Aaron Moreau-Cook Finally taking his CCNA test this coming Friday ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Subnet Question
Actually, I found this little tidbit on Fatkid.com. I have never tried it but it appears from their response that you can use them as subnet masks as well as in access lists... Not many people are aware that TCP/IP address masks neither need to be contiguous or have ones starting from the left. The following are examples of typical TCP/IP masks that you might see everyday: ... - 255.255.255.0 ... - 255.255.0.0 ... - 255.240.0.0 Here are a few valid masks that you probably have not seen before: 10101010.10101010.10101010.10101010 - 170.170.170.170 ... - 0.255.0.255 If you get a chance set "ip classless" on a Cisco router and try some of these goofy masks. Tim - Original Message - From: "Bradley J. Wilson" [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Sunday, September 03, 2000 7:36 AM Subject: Re: Subnet Question The answer to the question as stated would be false, but - you *can* use discontiguous masks in access lists, which can be a pretty handy feature sometimes. Sincerely, Bradley J. Wilson CCNA, CCDA, MCSE, CCSE, CNX-A, MCT, CTT - Original Message - From: Aaron Moreau-Cook To: [EMAIL PROTECTED] Sent: Saturday, September 02, 2000 8:47 PM Subject: Subnet Question Question taken from the CCNA Exam Cram book by Walters, Rees, and Coe. A subnet mask can have a value of 0.255.255.0 A) True B) False The Cisco answer would dictate that it is false, and in all functionality it is true. Hypothetically though it could be true, I rememeber this discusion a while ago, but I'm looking to see if I am smoking the proverbial crack. Thanks all! Aaron Moreau-Cook Finally taking his CCNA test this coming Friday ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Subnet Question
Chuck, Just tried it on a 3662 with IOS 12.1T and it didn't work. Rotuer(config-if)#ip address 10.1.1.1 0.255.255.0 Bad mask 0x00 for address 10.1.1.1 Too bad, it would had made a interesting trouble-shooting lab. Albert -Original Message- From: Chuck Larrieu [mailto:[EMAIL PROTECTED]] Sent: Sunday, September 03, 2000 3:06 AM To: Aaron Moreau-Cook; [EMAIL PROTECTED] Subject: RE: Subnet Question I hate questions like this. Can, May, Always, Never. RFC 1812 strongly discourages this practice. On the other hand, the world won't end if you do. You may even create a permanent income for yourself by setting up your network like this. ;- All the TCP stacks I have worked with allow this on the host side. It occurs to me I've never tried this on a Cisco router, even after the long discussion on the topic a few months ago. Next time I'm in the routers, I'll see what happens and report. Chuck -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Aaron Moreau-Cook Sent: Saturday, September 02, 2000 5:48 PM To: [EMAIL PROTECTED] Subject:Subnet Question Question taken from the CCNA Exam Cram book by Walters, Rees, and Coe. A subnet mask can have a value of 0.255.255.0 A) True B) False The Cisco answer would dictate that it is false, and in all functionality it is true. Hypothetically though it could be true, I rememeber this discusion a while ago, but I'm looking to see if I am smoking the proverbial crack. Thanks all! Aaron Moreau-Cook Finally taking his CCNA test this coming Friday ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Subnet Question
Golly, sorry to tell you this, but I think you are on the 'proverbial crack'... I would answer B on any Cisco, MS, Nortel or any other test you care to put in front of me... A subnet mask determines the place where the bits on the left (the network bits) are divided from the bits on the right (the host bits). If you had a subnet mask of 0.255.255.0 you would basicly be saying that the network you are on is the center 2 octets only, while the host bits are the first and last octet. I can't say that I have tried this on a private or a public network, but I cannot see this working. Either the equipment would keep you from setting this up, or the network would just not work. One of the central assumptions of TCP/IP is that the network MUST be on the right and the hosts MUST be on the left. That said, if you ever try this PLEASE let me know how it goes! HTH, Casey From: "Aaron Moreau-Cook" [EMAIL PROTECTED] Reply-To: "Aaron Moreau-Cook" [EMAIL PROTECTED] To: [EMAIL PROTECTED] Subject: Subnet Question Date: Sat, 2 Sep 2000 17:47:43 -0700 Question taken from the CCNA Exam Cram book by Walters, Rees, and Coe. A subnet mask can have a value of 0.255.255.0 A) True B) False The Cisco answer would dictate that it is false, and in all functionality it is true. Hypothetically though it could be true, I rememeber this discusion a while ago, but I'm looking to see if I am smoking the proverbial crack. Thanks all! Aaron Moreau-Cook Finally taking his CCNA test this coming Friday ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Share information about yourself, create your own public profile at http://profiles.msn.com. ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Subnet Question
This was a fascinating topic that was previously discussed back in July of 1999. I bookmarked it for reference, because I found the debate so interesting. You might want to search the archives for the thread "Theoretical question". To summarize the jist of the discussion, RFC 1812, declares discontiguous subnet masks as illegal. You'll find the specifics in Section 10.2.2, "Address and Prefix Initialization". -- Leigh Anne -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Casey Fahey Sent: Saturday, September 02, 2000 7:48 PM To: [EMAIL PROTECTED] Subject: Re: Subnet Question Golly, sorry to tell you this, but I think you are on the 'proverbial crack'... I would answer B on any Cisco, MS, Nortel or any other test you care to put in front of me... A subnet mask determines the place where the bits on the left (the network bits) are divided from the bits on the right (the host bits). If you had a subnet mask of 0.255.255.0 you would basicly be saying that the network you are on is the center 2 octets only, while the host bits are the first and last octet. I can't say that I have tried this on a private or a public network, but I cannot see this working. Either the equipment would keep you from setting this up, or the network would just not work. One of the central assumptions of TCP/IP is that the network MUST be on the right and the hosts MUST be on the left. That said, if you ever try this PLEASE let me know how it goes! HTH, Casey From: "Aaron Moreau-Cook" [EMAIL PROTECTED] Reply-To: "Aaron Moreau-Cook" [EMAIL PROTECTED] To: [EMAIL PROTECTED] Subject: Subnet Question Date: Sat, 2 Sep 2000 17:47:43 -0700 Question taken from the CCNA Exam Cram book by Walters, Rees, and Coe. A subnet mask can have a value of 0.255.255.0 A) True B) False The Cisco answer would dictate that it is false, and in all functionality it is true. Hypothetically though it could be true, I rememeber this discusion a while ago, but I'm looking to see if I am smoking the proverbial crack. Thanks all! Aaron Moreau-Cook Finally taking his CCNA test this coming Friday ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Share information about yourself, create your own public profile at http://profiles.msn.com. ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Subnet Question
Leigh Anne, Shortly after I sent my e-mail, I found the email thread in my archive. I also saved it because I found it to be facinating, I was quite shocked to find it in a test exam for the CCNA in the form of a True/False. It appears the answer may be true, but the "legal" answer is false. (Mental Note: What is red may be black). Someone tried it and they found it did not work on IOS (11.3 6T), or Linux. Here is a copy of the original post, which was agreed to theoretically work, but will not work due to RFC 1812's declariation of illegality. Enjoy! Start Post from July 8th, 1999 This is a purely theoretical question, and I see absolutely no practical reason for wanting to do this (other than complete insanity), but I'm curious... Is it possible to use a subnet mask with discontiguous 1s? For example, a subnet mask of 255.255.255.170 (expand it to binary - the last octet is 10101010)? This could give you networks and hosts of (say) x.x.x.128 (network A) x.x.x.129 (host on A) x.x.x.130 (network B) x.x.x.131 (host on B) x.x.x.132 (host on A) x.x.x.133 (host on A) x.x.x.134 (host on B) (my binary arithmetic may be wrong but hopefully you can see what I'm getting at) If this is possible, are there any situations where it might be applicable (short of a really nasty CCIE lab, maybe :-)? End Post from July 8th, 1999 -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Leigh Anne Chisholm Sent: Saturday, September 02, 2000 7:45 PM To: Casey Fahey; [EMAIL PROTECTED] Subject: RE: Subnet Question This was a fascinating topic that was previously discussed back in July of 1999. I bookmarked it for reference, because I found the debate so interesting. You might want to search the archives for the thread "Theoretical question". To summarize the jist of the discussion, RFC 1812, declares discontiguous subnet masks as illegal. You'll find the specifics in Section 10.2.2, "Address and Prefix Initialization". -- Leigh Anne -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Casey Fahey Sent: Saturday, September 02, 2000 7:48 PM To: [EMAIL PROTECTED] Subject: Re: Subnet Question Golly, sorry to tell you this, but I think you are on the 'proverbial crack'... I would answer B on any Cisco, MS, Nortel or any other test you care to put in front of me... A subnet mask determines the place where the bits on the left (the network bits) are divided from the bits on the right (the host bits). If you had a subnet mask of 0.255.255.0 you would basicly be saying that the network you are on is the center 2 octets only, while the host bits are the first and last octet. I can't say that I have tried this on a private or a public network, but I cannot see this working. Either the equipment would keep you from setting this up, or the network would just not work. One of the central assumptions of TCP/IP is that the network MUST be on the right and the hosts MUST be on the left. That said, if you ever try this PLEASE let me know how it goes! HTH, Casey From: "Aaron Moreau-Cook" [EMAIL PROTECTED] Reply-To: "Aaron Moreau-Cook" [EMAIL PROTECTED] To: [EMAIL PROTECTED] Subject: Subnet Question Date: Sat, 2 Sep 2000 17:47:43 -0700 Question taken from the CCNA Exam Cram book by Walters, Rees, and Coe. A subnet mask can have a value of 0.255.255.0 A) True B) False The Cisco answer would dictate that it is false, and in all functionality it is true. Hypothetically though it could be true, I rememeber this discusion a while ago, but I'm looking to see if I am smoking the proverbial crack. Thanks all! Aaron Moreau-Cook Finally taking his CCNA test this coming Friday ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Share information about yourself, create your own public profile at http://profiles.msn.com. ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: h
