DHCP Requests across VLANs [7:8689]
Hi all, In a Cat6509, we have created three VLANs. In one of the three VLANs, an NT Server is configured as a DHCP Server. My doubt no.1 is. Can a client in another VLAN get its DHCP request served by this DHCP Server. If yes, how this can be done. If not, is there any other way we can have all the clients in the three VLANs get IP Address from a single DHCP Server. My doubt no.2 is slightly off topic. If the clients in all three VLANs can get IP Address from the NT DHCP Server, Can I give IP Addresses from a single DHCP Scope. Thanks in Advance! S.Kalidasan Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=8689&t=8689 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: DHCP Requests across VLANs [7:8689]
Yes you can. The DHCP requests will have to be routed via the MSFC or an external router. As the DHCP requests are broadasts the router will not forward these by default. You will have to set up a helper address on each interface that a broadcast is received on specifying the destination unicast of the DHCP server. I hope this is clear. chris.b -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] Sent: 15 June 2001 10:41 To: [EMAIL PROTECTED] Subject: DHCP Requests across VLANs [7:8689] Hi all, In a Cat6509, we have created three VLANs. In one of the three VLANs, an NT Server is configured as a DHCP Server. My doubt no.1 is. Can a client in another VLAN get its DHCP request served by this DHCP Server. If yes, how this can be done. If not, is there any other way we can have all the clients in the three VLANs get IP Address from a single DHCP Server. My doubt no.2 is slightly off topic. If the clients in all three VLANs can get IP Address from the NT DHCP Server, Can I give IP Addresses from a single DHCP Scope. Thanks in Advance! S.Kalidasan This e-mail and any files transmitted with it are intended solely for the addressee and are confidential. They may also be legally privileged. Copyright in them is reserved by Delphis Consulting PLC ["Delphis"] and they must not be disclosed to, or used by, anyone other than the addressee. If you have received this e-mail and any accompanying files in error, you may not copy, publish or use them in any way and you should delete them from your system and notify us immediately.E-mails are not secure. Delphis does not accept responsibility for changes to e-mails that occur after they have been sent. Any opinions expressed in this e-mail may be personal to the author and may not necessarily reflect the opinions of Delphis. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=8691&t=8689 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: DHCP Requests across VLANs [7:8689]
If you served all your addresses from the same scope, you would have serious issues routing issues. Best practises dictate that you assign a scope per VLAN. Pete *** REPLY SEPARATOR *** On 6/15/2001 at 5:40 AM [EMAIL PROTECTED] wrote: >Hi all, > >In a Cat6509, we have created three VLANs. In one of the three VLANs, an NT >Server is configured as a DHCP Server. My doubt no.1 is. Can a client >in >another VLAN get its DHCP request served by this DHCP Server. If yes, how >this can be done. If not, is there any other way we can have all the >clients >in the three VLANs get IP Address from a single DHCP Server. > >My doubt no.2 is slightly off topic. If the clients in all three VLANs can >get IP Address from the NT DHCP Server, Can I give IP Addresses from a >single >DHCP Scope. > >Thanks in Advance! > >S.Kalidasan Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=8706&t=8689 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: DHCP Requests across VLANs [7:8689]
Use the ip helper-address command and you need a different scope for each Vlan. - Original Message - From: "[EMAIL PROTECTED]" To: Sent: Friday, June 15, 2001 5:40 AM Subject: DHCP Requests across VLANs [7:8689] > Hi all, > > In a Cat6509, we have created three VLANs. In one of the three VLANs, an NT > Server is configured as a DHCP Server. My doubt no.1 is. Can a client in > another VLAN get its DHCP request served by this DHCP Server. If yes, how > this can be done. If not, is there any other way we can have all the clients > in the three VLANs get IP Address from a single DHCP Server. > > My doubt no.2 is slightly off topic. If the clients in all three VLANs can > get IP Address from the NT DHCP Server, Can I give IP Addresses from a single > DHCP Scope. > > Thanks in Advance! > > S.Kalidasan Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=8710&t=8689 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: DHCP Requests across VLANs [7:8689]
There is an easy Win NT solution. You can have a one of the servers or workstations act as a DHCP relay for the other subnets. They will listen dor DHCP broadcats and forward them to the proper DHCP server. ""[EMAIL PROTECTED]"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Hi all, > > In a Cat6509, we have created three VLANs. In one of the three VLANs, an NT > Server is configured as a DHCP Server. My doubt no.1 is. Can a client in > another VLAN get its DHCP request served by this DHCP Server. If yes, how > this can be done. If not, is there any other way we can have all the clients > in the three VLANs get IP Address from a single DHCP Server. > > My doubt no.2 is slightly off topic. If the clients in all three VLANs can > get IP Address from the NT DHCP Server, Can I give IP Addresses from a single > DHCP Scope. > > Thanks in Advance! > > S.Kalidasan Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=8713&t=8689 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: DHCP Requests across VLANs [7:8689]
Start a session with the router and insert a 'ip helper' address. Be carefull though...by default, for whatever reason, cisco thinks netbios broadcast and name resolution along with dns and a few other broadcasts should be forwarded as well. You'll need to manually shut these off via 'no ip forward' example: interface Vlan1 ip address 10.40.48.1 255.255.240.0 ip helper-address 10.70.48.48 ip helper-address 10.70.80.30 ip helper-address 10.70.80.33 ipx network 104048 Then in global config do the following: no ip forward-protocol udp tftp no ip forward-protocol udp domain no ip forward-protocol udp time no ip forward-protocol udp netbios-ns no ip forward-protocol udp netbios-dgm -Patrick >>> "Vlade" 06/15/01 10:44AM >>> There is an easy Win NT solution. You can have a one of the servers or workstations act as a DHCP relay for the other subnets. They will listen dor DHCP broadcats and forward them to the proper DHCP server. ""[EMAIL PROTECTED]"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Hi all, > > In a Cat6509, we have created three VLANs. In one of the three VLANs, an NT > Server is configured as a DHCP Server. My doubt no.1 is. Can a client in > another VLAN get its DHCP request served by this DHCP Server. If yes, how > this can be done. If not, is there any other way we can have all the clients > in the three VLANs get IP Address from a single DHCP Server. > > My doubt no.2 is slightly off topic. If the clients in all three VLANs can > get IP Address from the NT DHCP Server, Can I give IP Addresses from a single > DHCP Scope. > > Thanks in Advance! > > S.Kalidasan Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=8742&t=8689 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: DHCP Requests across VLANs [7:8689]
And no... You need to define 3 scopes one for each vlan/network. The router then unicasts the original broadcast and replaces the network field which originates as 0 with the proper subnet the station is on. The dhcp server then sees a request from the workstation and answers appropriately for that network and the router is all done. -Patrick >>> "Vlade" 06/15/01 10:44AM >>> There is an easy Win NT solution. You can have a one of the servers or workstations act as a DHCP relay for the other subnets. They will listen dor DHCP broadcats and forward them to the proper DHCP server. ""[EMAIL PROTECTED]"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Hi all, > > In a Cat6509, we have created three VLANs. In one of the three VLANs, an NT > Server is configured as a DHCP Server. My doubt no.1 is. Can a client in > another VLAN get its DHCP request served by this DHCP Server. If yes, how > this can be done. If not, is there any other way we can have all the clients > in the three VLANs get IP Address from a single DHCP Server. > > My doubt no.2 is slightly off topic. If the clients in all three VLANs can > get IP Address from the NT DHCP Server, Can I give IP Addresses from a single > DHCP Scope. > > Thanks in Advance! > > S.Kalidasan Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=8743&t=8689 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: DHCP Requests across VLANs [7:8689]
I think he said he has one DHCP server, so this example shows three different DHCP servers. Also, in this example you will not need an IP helpder address for the DHCP server that is connected directly to this segment, in this example you will not need "ip helper-address 10.70.48.48" under interface vlan 1. One common application that requires helper addresses is Dynamic Host Configuration Protocol (DHCP), which is defined in RFC 1531. DHCP protocol information is carried inside of BOOTP packets. To enable BOOTP broadcast forwarding for a set of clients, configure a helper address on the router interface closest to the client. The helper address should specify the address of the DHCP server. If you have multiple servers, you can configure one helper address for each server. Since BOOTP packets are forwarded by default, DHCP information can now be forwarded by the router. The DHCP server now receives broadcasts from the DHCP clients. It's not that Cisco thinks should be forwarded as well but the "ip helper-address" by nature of it's feature forward all this UDP broadcast. It is correct to limit these UDP that are not needed to be no forwarded. >From: "Patrick Ramsey" >Reply-To: "Patrick Ramsey" >To: [EMAIL PROTECTED] >Subject: Re: DHCP Requests across VLANs [7:8689] >Date: Fri, 15 Jun 2001 14:38:28 -0400 > >Start a session with the router and insert a 'ip helper' address. > >Be carefull though...by default, for whatever reason, cisco thinks netbios >broadcast and name resolution along with dns and a few other broadcasts >should be forwarded as well. You'll need to manually shut these off via >'no >ip forward' > >example: > >interface Vlan1 > ip address 10.40.48.1 255.255.240.0 > ip helper-address 10.70.48.48 > ip helper-address 10.70.80.30 > ip helper-address 10.70.80.33 > ipx network 104048 > >Then in global config do the following: > >no ip forward-protocol udp tftp >no ip forward-protocol udp domain >no ip forward-protocol udp time >no ip forward-protocol udp netbios-ns >no ip forward-protocol udp netbios-dgm > > >-Patrick > > > >>> "Vlade" 06/15/01 10:44AM >>> >There is an easy Win NT solution. You can have a one of the servers or >workstations act as a DHCP relay for the other subnets. They will listen >dor >DHCP broadcats and forward them to the proper DHCP server. >""[EMAIL PROTECTED]"" wrote in >message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > Hi all, > > > > In a Cat6509, we have created three VLANs. In one of the three VLANs, an >NT > > Server is configured as a DHCP Server. My doubt no.1 is. Can a >client >in > > another VLAN get its DHCP request served by this DHCP Server. If yes, >how > > this can be done. If not, is there any other way we can have all the >clients > > in the three VLANs get IP Address from a single DHCP Server. > > > > My doubt no.2 is slightly off topic. If the clients in all three VLANs >can > > get IP Address from the NT DHCP Server, Can I give IP Addresses from a >single > > DHCP Scope. > > > > Thanks in Advance! > > > > S.Kalidasan _ Get your FREE download of MSN Explorer at http://explorer.msn.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=8852&t=8689 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: DHCP Requests across VLANs [7:8689]
Greetings, Question 1) Yes - using the "ip helper address " command on the router interfaces for the VLANs that don't have a DHCP server. Question 2) Technically, yes you can. But only by bridging on the router interfaces for the VLANs. However, it does fall under the first rule of networking, "Just because you can, doesn't mean you should." Its a messy solution and you should only do it if you absolutely have to and its short term (such as an addressing migration). Let me know if there's anything else I can help with. Karen *** REPLY SEPARATOR *** On 6/15/2001 at 5:40 AM [EMAIL PROTECTED] wrote: >Hi all, > >In a Cat6509, we have created three VLANs. In one of the three VLANs, an NT >Server is configured as a DHCP Server. My doubt no.1 is. Can a client in >another VLAN get its DHCP request served by this DHCP Server. If yes, how >this can be done. If not, is there any other way we can have all the clients >in the three VLANs get IP Address from a single DHCP Server. > >My doubt no.2 is slightly off topic. If the clients in all three VLANs can >get IP Address from the NT DHCP Server, Can I give IP Addresses from a single >DHCP Scope. > >Thanks in Advance! > >S.Kalidasan Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=9331&t=8689 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
