RE: Proper network design? [7:49536]
Is this what is happening? Would it not be looking at it's routing table, seeing that another host on the same subnet is the next hop, and then sending an ICMP re-direct message to the originating host, telling it to go directly to the 192.168.0.100 host? Symon -Original Message- From: sam sneed [mailto:[EMAIL PROTECTED]] Sent: 24 July 2002 22:54 To: [EMAIL PROTECTED] Subject: Re: Proper network design? [7:49536] This is not the classcial router on a stick model. That model is for routing between VLANs on a router with 1 interface using trunking. All this router is doing is taking packets from its eth1 interface, comparing them to its routing table and forwarding out the same eth1 interface for the gateway which is designated for the 192.168.2.0 network. This is totally legitmate and no secondary or subinterfaces are needed. Frank H wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... The router on a stick effect comes from this: ip route 192.168.2.0 255.255.255.0 192.168.0.100 All traffic destined to any network not on 192.168.0.0 goes to the gateway (192.168.0.1) on interface ethernet 1. The router then re-routes 192.168.2.0 traffic back on the 192.168.0.0 network to 192.168.0.100 (the router on a stick effect). Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=49642t=49536 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Proper network design? [7:49536]
Thanks for your explanation - I can understand my setup very clearly now. I originally asked this question because I have not been exposed to that situation before (I'm at the CCNA level). You are correct in saying that the cellular box does routing for the 192.168.2.0 network. I was also incorrect to call my setup a router on a stick as another person pointed out - it looks similar though. The network drawing was correct. The Linux box that was acting as a router in the original setup was replaced with the Cisco router in order to correct the problem of only one 192.168.0.0 network host being able to talk to cellular hosts on the 192.168.2.0 network. My setup is exactly the same as the Chicago/San Francisco/New York situation you described. I'm just curious as to why the Linux box could not be configured to do the same job as the Cisco router (with the added static route). I'll have to talk to our network guy to see if he can make the Linux box do the same job so I can take my Cisco router back home. Thanks to all for your help. Frank Priscilla Oppenheimer wrote: Frank H wrote: Proper network design? I have a few questions for the group that maybe someone can answer. From my studies when I got CCNA certified, I understood that different networks were ALWAYS separated by a router. At my company we have this equipment that was purchased several months ago that acts as a digital cellular network. It was set up and was able to operate, but only in a limited way. Basically, this is the setup - the digital cellular network was on the 192.168.2.0 subnet (subnet mask 255.255.255.0). The company development LAN was on the 192.168.0.0 subnet (subnet mask 255.255.255.0). The two small networks (less than 10 hosts in each subnet) were all tied together at a 24 port hub. The gateway to the Internet was through a Linux box. The digital cellular network was basically a box (with IP address 192.168.0.100) that passed packets to network 192.168.2.0 through a low power transmitter to the cellular hosts in the 192.168.2.0 subnet. With this setup, only one desktop host on the 192.168.0.0 network could communicate to the 192.168.2.0 cellular network (desktop host 192.168.0.20). The problem of only one desktop host in the 192.168.0.0 network being able to communicate with the 192.168.2.0 network was solved by replacing the Linux box with a Cisco 2514 router (with two ethernet interfaces). The configuration for the router was exactly the same as the Linux box except for one small addition. The following line was added as a static route: ip route 192.168.2.0 255.255.255.0 192.168.0.100 Now let me ask you, have you ever seen a router that gets a packet on one interface pass it right back out the SAME interface back to another host on that same network? Sure, it happens all the time. There's nothing non-standard about this. It's quite normal for a router to receive a packet on an interface, look into its routing table, and determine that the packet needs to go back out the same interface it came in on. For example, let's say you have a LAN in Chicago that has two routers on it. One router has a WAN connection to San Francisco and the other router has a WAN connection to New York. Clients on the LAN in Chicago can only be configured with one default gateway. So, let's say that you tell them their default gateway is the router that goes to New York. When the clients send a pcket to San Francisco, the packet goes to the router that connects to New York. That router sends the packet back out the LAN to the router that goes to San Francisco. The router can send an ICMP Redirect to the end host saying essentially don't use me, use this other router. The host may or may not follow that advice. This is sometimes called the extra hop problem, although it's not really a problem. In your case, since the cellular box is a bit weird (only supports one host talking through it I think you said), you would probably want to disable ICMP Redirects. Our setup basically ties two DIFFERENT class C subnets together through a hub and the Cisco router makes it all work perfectly. A hub? Now that part is confusing. Are you referring to the cellular box, which sounds like a router to me. It's on two networks, 192.168.0.0 and 192.168.2.0. It's at least a device that can do forwarding based on Layer 3. This doesn't sound like standard network design as I've seen it described in any text so far. I'll describe it a little more for clarity. If i'm on a desktop PC (IP address 192.168.0.20) and ping IP address 192.168.2.2, windows will send that packet to the default gateway (configured as 192.168.0.1 in windows network applet - which is the Cisco router) since it lies in a different network (since the subnet mask is 255.255.255.0). The Cisco router receives this packet destined for the 192.168.2.0 network and
RE: Proper network design? [7:49536]
I'm curious about why the Linux box couldn't be configured to do the same job as the Cisco router also. Let us know if your Linux colleagues tell you. Wouldn't that be great if they could put the Linux box back and give you the router for your home lab? ;-) Thanks for a great discussion. Priscilla Frank H wrote: Thanks for your explanation - I can understand my setup very clearly now. I originally asked this question because I have not been exposed to that situation before (I'm at the CCNA level). You are correct in saying that the cellular box does routing for the 192.168.2.0 network. I was also incorrect to call my setup a router on a stick as another person pointed out - it looks similar though. The network drawing was correct. The Linux box that was acting as a router in the original setup was replaced with the Cisco router in order to correct the problem of only one 192.168.0.0 network host being able to talk to cellular hosts on the 192.168.2.0 network. My setup is exactly the same as the Chicago/San Francisco/New York situation you described. I'm just curious as to why the Linux box could not be configured to do the same job as the Cisco router (with the added static route). I'll have to talk to our network guy to see if he can make the Linux box do the same job so I can take my Cisco router back home. Thanks to all for your help. Frank Priscilla Oppenheimer wrote: Frank H wrote: Proper network design? I have a few questions for the group that maybe someone can answer. From my studies when I got CCNA certified, I understood that different networks were ALWAYS separated by a router. At my company we have this equipment that was purchased several months ago that acts as a digital cellular network. It was set up and was able to operate, but only in a limited way. Basically, this is the setup - the digital cellular network was on the 192.168.2.0 subnet (subnet mask 255.255.255.0). The company development LAN was on the 192.168.0.0 subnet (subnet mask 255.255.255.0). The two small networks (less than 10 hosts in each subnet) were all tied together at a 24 port hub. The gateway to the Internet was through a Linux box. The digital cellular network was basically a box (with IP address 192.168.0.100) that passed packets to network 192.168.2.0 through a low power transmitter to the cellular hosts in the 192.168.2.0 subnet. With this setup, only one desktop host on the 192.168.0.0 network could communicate to the 192.168.2.0 cellular network (desktop host 192.168.0.20). The problem of only one desktop host in the 192.168.0.0 network being able to communicate with the 192.168.2.0 network was solved by replacing the Linux box with a Cisco 2514 router (with two ethernet interfaces). The configuration for the router was exactly the same as the Linux box except for one small addition. The following line was added as a static route: ip route 192.168.2.0 255.255.255.0 192.168.0.100 Now let me ask you, have you ever seen a router that gets a packet on one interface pass it right back out the SAME interface back to another host on that same network? Sure, it happens all the time. There's nothing non-standard about this. It's quite normal for a router to receive a packet on an interface, look into its routing table, and determine that the packet needs to go back out the same interface it came in on. For example, let's say you have a LAN in Chicago that has two routers on it. One router has a WAN connection to San Francisco and the other router has a WAN connection to New York. Clients on the LAN in Chicago can only be configured with one default gateway. So, let's say that you tell them their default gateway is the router that goes to New York. When the clients send a pcket to San Francisco, the packet goes to the router that connects to New York. That router sends the packet back out the LAN to the router that goes to San Francisco. The router can send an ICMP Redirect to the end host saying essentially don't use me, use this other router. The host may or may not follow that advice. This is sometimes called the extra hop problem, although it's not really a problem. In your case, since the cellular box is a bit weird (only supports one host talking through it I think you said), you would probably want to disable ICMP Redirects. Our setup basically ties two DIFFERENT class C subnets together through a hub and the Cisco router makes it all work perfectly. A hub? Now that part is confusing. Are you referring to the cellular box, which sounds like a router to me. It's on two networks, 192.168.0.0 and 192.168.2.0. It's at least a device that can do forwarding based on Layer 3. This doesn't sound like standard network design as I've seen it described in any text so far.
RE: Proper network design? [7:49536]
Can you post the config of the router? Does the Ethernet interface have sub-interfaces? One for each subnet? The answer is probably in the configuration of the interface on the router. What IP and Subnet mask does it have? Could be that the subnet mask of the router Ethernet is 255.255.240.0 or something less than a /24, therefore the router Ethernet network contains both 192.168.0.0/24 and 192.168.2.0/24. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=49537t=49536 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Proper network design? [7:49536]
No subinterfaces are used. Here's the Cisco 2514 config: Router#show startup-config Using 940 out of 32762 bytes ! version 12.1 service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname Router ip subnet-zero ! interface Ethernet0 description outside ip address xxx.xxx.xxx.90 255.255.255.128 ip nat outside no cdp enable ! interface Ethernet1 description inside ip address 192.168.0.1 255.255.255.0 ip nat inside no cdp enable ! interface Serial0 no ip address shutdown ! ! no ip address shutdown ! ip nat pool test xxx.xxx.xxx.90 xxx.xxx.xxx.90 netmask 255.255.255.128 ip nat inside source list 1 pool test overload ip classless ip route 0.0.0.0 0.0.0.0 xxx.xxx.xxx.1 ip route 192.168.2.0 255.255.255.0 192.168.0.100 no ip http server ! access-list 1 permit 192.168.0.0 0.0.0.255 access-list 1 permit 192.168.2.0 0.0.0.255 ! ! line con 0 line aux 0 line vty 0 4 ! end Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=49540t=49536 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Proper network design? [7:49536]
192.168.0.100 is what is doing the real routing then for 192.168.2.0/24. If you follow the path, from a 192.168.0.20 machine to 192.168.2.20 say, it goes from 192.168.0.20, to the default gateway, 192.168.0.1 which checks the route table and sends it to 192.168.0.100 (which is on the same network as E0 so you're right about routers routing between networks.), then 192.168.0.100 must know where 192.168.2.0/24 is. All the router is doing is routing 192.168.2.0/24 traffic to the Linux box first. Its not that the router knows where 192.168.2.0/24 is, its just sayin 192.168.0.100 knows so go there first. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=49543t=49536 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Proper network design? [7:49536]
Yes, I have installed a few. It is called a 'one-arm router' or 'router on a stick'. Cisco has some doc's on it, but I would doubt that the hub is a hub. One-arm routers make use of vlans assigned to sub-interfaces. Although I am sure by just assigning the sub-intf the proper segment and the route statement, you could use a hub. Haven't tried that one yet, but I will. It is not a widely know configuration anymore. It was a cheap way to install a router when interface were very expensive. ~Michael -Original Message- From: Frank H [mailto:[EMAIL PROTECTED]] Sent: Wednesday, July 24, 2002 11:26 AM To: [EMAIL PROTECTED] Subject: Proper network design? [7:49536] Proper network design? I have a few questions for the group that maybe someone can answer. From my studies when I got CCNA certified, I understood that different networks were ALWAYS separated by a router. At my company we have this equipment that was purchased several months ago that acts as a digital cellular network. It was set up and was able to operate, but only in a limited way. Basically, this is the setup - the digital cellular network was on the 192.168.2.0 subnet (subnet mask 255.255.255.0). The company development LAN was on the 192.168.0.0 subnet (subnet mask 255.255.255.0). The two small networks (less than 10 hosts in each subnet) were all tied together at a 24 port hub. The gateway to the Internet was through a Linux box. The digital cellular network was basically a box (with IP address 192.168.0.100) that passed packets to network 192.168.2.0 through a low power transmitter to the cellular hosts in the 192.168.2.0 subnet. With this setup, only one desktop host on the 192.168.0.0 network could communicate to the 192.168.2.0 cellular network (desktop host 192.168.0.20). The problem of only one desktop host in the 192.168.0.0 network being able to communicate with the 192.168.2.0 network was solved by replacing the Linux box with a Cisco 2514 router (with two ethernet interfaces). The configuration for the router was exactly the same as the Linux box except for one small addition. The following line was added as a static route: ip route 192.168.2.0 255.255.255.0 192.168.0.100 Now let me ask you, have you ever seen a router that gets a packet on one interface pass it right back out the SAME interface back to another host on that same network? Our setup basically ties two DIFFERENT class C subnets together through a hub and the Cisco router makes it all work perfectly. This doesn't sound like standard network design as I've seen it described in any text so far. I'll describe it a little more for clarity. If i'm on a desktop PC (IP address 192.168.0.20) and ping IP address 192.168.2.2, windows will send that packet to the default gateway (configured as 192.168.0.1 in windows network applet - which is the Cisco router) since it lies in a different network (since the subnet mask is 255.255.255.0). The Cisco router receives this packet destined for the 192.168.2.0 network and since it matches it with the above static route, sends it back out the same interface it came in on, back to another host (192.168.0.100 - the cellular transmitter box) out to the cellular host (192.168.2.2). This is the way the cellular network equipment manufacturer intended it to work. The setup works, but it sounds really weird and nonstandard. Has anyone else encountered such a setup or something similar before? Is this a kind of network design that is done often? Doesn't a router normally always route packets from one interface to another? Thanks in advance for your responses. Frank Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=49546t=49536 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Proper network design? [7:49536]
If I read this correctly ... (always a big assumption :) ) This may also arise when a network outgrows an initial IP range, and rather than redesign/re-address every host they just hemorrhage another block ... Or, the .100 box could be hosting a DMZ ? Or, for some reason, it was decided that one block was going to have 'more access' than another, so the 2.x subnet was thrown behind another router as a choke point? Thanks! TJ -Original Message- From: Frank H [mailto:[EMAIL PROTECTED]] Sent: Wednesday, July 24, 2002 12:52 PM To: [EMAIL PROTECTED] Subject: RE: Proper network design? [7:49536] No subinterfaces are used. Here's the Cisco 2514 config: Router#show startup-config Using 940 out of 32762 bytes ! version 12.1 service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname Router ip subnet-zero ! interface Ethernet0 description outside ip address xxx.xxx.xxx.90 255.255.255.128 ip nat outside no cdp enable ! interface Ethernet1 description inside ip address 192.168.0.1 255.255.255.0 ip nat inside no cdp enable ! interface Serial0 no ip address shutdown ! ! no ip address shutdown ! ip nat pool test xxx.xxx.xxx.90 xxx.xxx.xxx.90 netmask 255.255.255.128 ip nat inside source list 1 pool test overload ip classless ip route 0.0.0.0 0.0.0.0 xxx.xxx.xxx.1 ip route 192.168.2.0 255.255.255.0 192.168.0.100 no ip http server ! access-list 1 permit 192.168.0.0 0.0.0.255 access-list 1 permit 192.168.2.0 0.0.0.255 ! ! line con 0 line aux 0 line vty 0 4 ! end * The information in this email is confidential and may be legally privileged. It is intended solely for the addressee. Access to this email by anyone else is unauthorized. If you are not the intended recipient, any disclosure, copying, distribution or any action taken or omitted to be taken in reliance on it, is prohibited and may be unlawful. When addressed to our clients any opinions or advice contained in this email are subject to the terms and conditions expressed in the governing KPMG client engagement letter. * Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=49557t=49536 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Proper network design? [7:49536]
Now I understand. I read a few articles on the Cisco site after searching for the term router on a stick and found a good explanation. Thanks for your help. Frank Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=49558t=49536 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Proper network design? [7:49536]
I thought you said that this was a 2514. Don't they just have 10Mb Ethernet ports? Can you have sub-interfaces on a 10Mb port? Are you sure you are not using both ports on the 2514? - Original Message - From: Frank H To: Sent: Wednesday, July 24, 2002 2:55 PM Subject: RE: Proper network design? [7:49536] Now I understand. I read a few articles on the Cisco site after searching for the term router on a stick and found a good explanation. Thanks for your help. Frank Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=49566t=49536 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Proper network design? [7:49536]
Yes, I am using a 2514. It does have 2 10BaseT interfaces (through AUI adapters). I am not using subinterfaces. Both ports are used - one port goes to the Internet (for hosts that require Internet access) and the other connects directly to the 24 port hub which resides within the internal LAN. This internal LAN (network 192.168.0.0/24) can also communicate with network 192.168.2.0/24 (also connected on the hub) because the 2514 routes 192.168.2.0/24 traffic back to a cellular network host controller (192.168.0.100/24). The 2514 is acting as a regular router for Internet traffic and a router on a stick for 192.168.2.0/24 traffic. It was strange for me at first, but now I get the picture. Frank Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=49569t=49536 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Proper network design? [7:49536]
I assume you are using primary and secondary IP address on this one ethernet interface (which is creating the router on a stick effect)? Rob Frank H wrote: Yes, I am using a 2514. It does have 2 10BaseT interfaces (through AUI adapters). I am not using subinterfaces. Both ports are used - one port goes to the Internet (for hosts that require Internet access) and the other connects directly to the 24 port hub which resides within the internal LAN. This internal LAN (network 192.168.0.0/24) can also communicate with network 192.168.2.0/24 (also connected on the hub) because the 2514 routes 192.168.2.0/24 traffic back to a cellular network host controller (192.168.0.100/24). The 2514 is acting as a regular router for Internet traffic and a router on a stick for 192.168.2.0/24 traffic. It was strange for me at first, but now I get the picture. Frank Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=49576t=49536 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Proper network design? [7:49536]
No, just one IP address on each interface. Check my earlier post for the full configuration. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=49578t=49536 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Proper network design? [7:49536]
The router on a stick effect comes from this: ip route 192.168.2.0 255.255.255.0 192.168.0.100 All traffic destined to any network not on 192.168.0.0 goes to the gateway (192.168.0.1) on interface ethernet 1. The router then re-routes 192.168.2.0 traffic back on the 192.168.0.0 network to 192.168.0.100 (the router on a stick effect). Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=49579t=49536 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Proper network design? [7:49536]
This is not the classcial router on a stick model. That model is for routing between VLANs on a router with 1 interface using trunking. All this router is doing is taking packets from its eth1 interface, comparing them to its routing table and forwarding out the same eth1 interface for the gateway which is designated for the 192.168.2.0 network. This is totally legitmate and no secondary or subinterfaces are needed. Frank H wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... The router on a stick effect comes from this: ip route 192.168.2.0 255.255.255.0 192.168.0.100 All traffic destined to any network not on 192.168.0.0 goes to the gateway (192.168.0.1) on interface ethernet 1. The router then re-routes 192.168.2.0 traffic back on the 192.168.0.0 network to 192.168.0.100 (the router on a stick effect). Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=49580t=49536 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Proper network design? [7:49536]
I was under the assumption that a router on a stick was a router that was performing routing using one interface and virtually trunking 2 or more subnets with interface vlans set up on the router. Larry Letterman Cisco Systems [EMAIL PROTECTED] -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] Sent: Wednesday, July 24, 2002 2:32 PM To: [EMAIL PROTECTED] Subject: Re: Proper network design? [7:49536] No, just one IP address on each interface. Check my earlier post for the full configuration. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=49581t=49536 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Proper network design? [7:49536]
I understand this configuration, but question how the 192.168.2.2 machine knows how to get back to the 192.168.0.20. I don't question that it will work, but if it is not a router interface with 2 addresses from each segment defined, then what default gateway does the 192.168.2.2 machine use? If this configuration is as you stated, and the static route is in place, then there must also be a route defined in the machine on the 192.168.2.2 that routes off it's subnet to the 192.168.0.1 interface of the router. In other words, your 192.168.2.2 machine also has a static route (default route) defined on it to know how to get to the other segment (ie, forwarded to the 192.168.0.1 router interface). Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=49584t=49536 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Proper network design? [7:49536]
I am still lost how can a router with a 10Mb interface act as a Router on a stick? I may be missing something. Could you show us a diagram this is very interesting? How does the router know that there are two different subnets connected if you don't tell it? I think it has something to do with the router looking at the 192 subnets as one network. I bet that wouldn't act as a ROAS if you changed one of the networks to say a 10 subnet. Basically what you are saying in that if you want to route all you have to do is connect different networks to a hub, connect the hub to a single router port and then it will just start routing. I would love to see the output of that one. Are you sure that the router is doing the routing or is another device on the physical segment providing that service. I know that a host configured with the address of 10.10.0.1/16 will be able to ping a host configured as 10.10.0.100/24. I believe that something similar is going on here. Some debugs and configs would be great cause you learn something new everyday. - Original Message - From: Frank H To: Sent: Wednesday, July 24, 2002 4:43 PM Subject: Re: Proper network design? [7:49536] Yes, I am using a 2514. It does have 2 10BaseT interfaces (through AUI adapters). I am not using subinterfaces. Both ports are used - one port goes to the Internet (for hosts that require Internet access) and the other connects directly to the 24 port hub which resides within the internal LAN. This internal LAN (network 192.168.0.0/24) can also communicate with network 192.168.2.0/24 (also connected on the hub) because the 2514 routes 192.168.2.0/24 traffic back to a cellular network host controller (192.168.0.100/24). The 2514 is acting as a regular router for Internet traffic and a router on a stick for 192.168.2.0/24 traffic. It was strange for me at first, but now I get the picture. Frank Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=49585t=49536 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Proper network design? [7:49536]
I re-read your initial question... I would assume that 192.168.0.100 is also acting as a router...if this is true, then this would work... Is the cellular device also acting as a router? Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=49586t=49536 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Proper network design? [7:49536]
192.168.0.20192.168.0.1 (Router) (Host) | Static forwarding to 0.100 | | | | 192.168.0.100 (Acting as Router) Cell Device 192.168.2.1 | | | | 192.168.2.2 (Host) Is this it? Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=49588t=49536 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Proper network design? [7:49536]
The router doesn't know there are 2 segments on the Ethernet. The static route is routing packets destined for the 192.168.2.0/24 to 192.168.0.100. That device is also doing routing. Linux box I think. My question is how does 192.168.0.100 know of both subnets. Does it have 2 interfaces? I'm assuming that 192.168.2.0/24 devices have a default gateway of the Linux box, not the 2514 router. It can't have the router as its default gateway, cause the router doesn't have a 192.168.2.0/24 address. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=49587t=49536 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Proper network design? [7:49536]
Yes, Ben...I think that is what he is saying...I made a diagram in a past post. Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=49589t=49536 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Proper network design? [7:49536]
Frank H wrote: Proper network design? I have a few questions for the group that maybe someone can answer. From my studies when I got CCNA certified, I understood that different networks were ALWAYS separated by a router. At my company we have this equipment that was purchased several months ago that acts as a digital cellular network. It was set up and was able to operate, but only in a limited way. Basically, this is the setup - the digital cellular network was on the 192.168.2.0 subnet (subnet mask 255.255.255.0). The company development LAN was on the 192.168.0.0 subnet (subnet mask 255.255.255.0). The two small networks (less than 10 hosts in each subnet) were all tied together at a 24 port hub. The gateway to the Internet was through a Linux box. The digital cellular network was basically a box (with IP address 192.168.0.100) that passed packets to network 192.168.2.0 through a low power transmitter to the cellular hosts in the 192.168.2.0 subnet. With this setup, only one desktop host on the 192.168.0.0 network could communicate to the 192.168.2.0 cellular network (desktop host 192.168.0.20). The problem of only one desktop host in the 192.168.0.0 network being able to communicate with the 192.168.2.0 network was solved by replacing the Linux box with a Cisco 2514 router (with two ethernet interfaces). The configuration for the router was exactly the same as the Linux box except for one small addition. The following line was added as a static route: ip route 192.168.2.0 255.255.255.0 192.168.0.100 Now let me ask you, have you ever seen a router that gets a packet on one interface pass it right back out the SAME interface back to another host on that same network? Sure, it happens all the time. There's nothing non-standard about this. It's quite normal for a router to receive a packet on an interface, look into its routing table, and determine that the packet needs to go back out the same interface it came in on. For example, let's say you have a LAN in Chicago that has two routers on it. One router has a WAN connection to San Francisco and the other router has a WAN connection to New York. Clients on the LAN in Chicago can only be configured with one default gateway. So, let's say that you tell them their default gateway is the router that goes to New York. When the clients send a pcket to San Francisco, the packet goes to the router that connects to New York. That router sends the packet back out the LAN to the router that goes to San Francisco. The router can send an ICMP Redirect to the end host saying essentially don't use me, use this other router. The host may or may not follow that advice. This is sometimes called the extra hop problem, although it's not really a problem. In your case, since the cellular box is a bit weird (only supports one host talking through it I think you said), you would probably want to disable ICMP Redirects. Our setup basically ties two DIFFERENT class C subnets together through a hub and the Cisco router makes it all work perfectly. A hub? Now that part is confusing. Are you referring to the cellular box, which sounds like a router to me. It's on two networks, 192.168.0.0 and 192.168.2.0. It's at least a device that can do forwarding based on Layer 3. This doesn't sound like standard network design as I've seen it described in any text so far. I'll describe it a little more for clarity. If i'm on a desktop PC (IP address 192.168.0.20) and ping IP address 192.168.2.2, windows will send that packet to the default gateway (configured as 192.168.0.1 in windows network applet - which is the Cisco router) since it lies in a different network (since the subnet mask is 255.255.255.0). The Cisco router receives this packet destined for the 192.168.2.0 network and since it matches it with the above static route, sends it back out the same interface it came in on, back to another host (192.168.0.100 - the cellular transmitter box) out to the cellular host (192.168.2.2). That's quite normal. This is the way the cellular network equipment manufacturer intended it to work. The setup works, but it sounds really weird and nonstandard. Has anyone else encountered such a setup or something similar before? Is this a kind of network design that is done often? Doesn't a router normally always route packets from one interface to another? Depends on the topology. Maybe the router can't get there itself but knows that another router (or host or cellular box or whatever) can. I hope this makes sense. Priscilla Oppenheimer http://www.priscilla.com Thanks in advance for your responses. Frank Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=49594t=49536 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Proper network design? [7:49536]
Frank H wrote: Yes, I am using a 2514. It does have 2 10BaseT interfaces (through AUI adapters). I am not using subinterfaces. Both ports are used - one port goes to the Internet (for hosts that require Internet access) and the other connects directly to the 24 port hub which resides within the internal LAN. This internal LAN (network 192.168.0.0/24) can also communicate with network 192.168.2.0/24 (also connected on the hub) That last statement about 192.168.2.0/24 also being connected to the hub doesn't make sense unless what you mean is that the cellular box connects to the hub. But the box connects to the hub on its 192.168.0.0 side, not on its 192.168.2.0 side, right? The 192.168.2.0 network can't be on the hub? If it is, why bother with a cellular network? In fact, you told us earlier that the devices on 192.168.2.0 use cellular. Just trying to make sense of it. The drawing that Robert C. did makes sense. If we are making too many assumptions, just let us know. Thanks. Priscilla Oppenheimer http://www.priscilla.com because the 2514 routes 192.168.2.0/24 traffic back to a cellular network host controller (192.168.0.100/24). The 2514 is acting as a regular router for Internet traffic and a router on a stick for 192.168.2.0/24 traffic. It was strange for me at first, but now I get the picture. Frank Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=49596t=49536 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Proper network design? [7:49536]
sam sneed wrote: This is not the classcial router on a stick model. That model is for routing between VLANs on a router with 1 interface using trunking. All this router is doing is taking packets from its eth1 interface, comparing them to its routing table and forwarding out the same eth1 interface for the gateway which is designated for the 192.168.2.0 network. This is totally legitmate and no secondary or subinterfaces are needed. I agree with Sam that this is not the classical router on a stick model. Although it may help to understand what is happening to call this router on a stick, your situation is not what is usually described by that phrase. The phrase is used when you have a single router interface that is doing inter-VLAN routing. That's not what you have. You have a typical case where the default gateway can't get to the destination network except by sending the packet back out to another box on the LAN. Not a big deal, but just thought you might want to know that you could confuse people by calling this router on a stick. Priscilla Oppenheimer http://www.priscilla.com Frank H wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... The router on a stick effect comes from this: ip route 192.168.2.0 255.255.255.0 192.168.0.100 All traffic destined to any network not on 192.168.0.0 goes to the gateway (192.168.0.1) on interface ethernet 1. The router then re-routes 192.168.2.0 traffic back on the 192.168.0.0 network to 192.168.0.100 (the router on a stick effect). Message Posted at: http://www.groupstudy.com/form/read.php?f=7i=49598t=49536 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
