Connection between 2 routers across a Switch

Answered Question
Apr 5th, 2006

I have a link on for example VLAN 211 and I need devices on VLAN 1 to get access through.

How can I do this.

The Link line is on VLAN 211 but the switches can only be on VLAN 1 as they are just actng as hubs and VALN 211 cannot be created on them.

Thank for your help

I have this problem too.
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Correct Answer by ankurbhasin about 8 years 3 weeks ago

Hi Friend,

Yes you can do that and now you router is not taking via vlan 211 but they are simply connected from one router to another via vlan 1.

router--vlan 1(2950)vlan 1(cat6k)trunk(3550)--vlan 1(2950)vlan 1--router.

Hope you goy my point now.

HTH, if yes please rate the post.

Ankur

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ankurbhasin Wed, 04/05/2006 - 08:05

Hi Friend,

Can you be more clear with the setup. Your description is not very clear.

What is your topology and what all neywrk devices you have and what exactly you want.

Regards,

Ankur

londint Wed, 04/05/2006 - 08:16

Thanks

We have a 1GB Link between a 6506 and a 3550 Switch configured for VLAN 211.

We have connected a 2950 via default VLAN 1 access link to the 6506 and another 2950 via default VLAN 1 to the 3550. The 2950 are acting as ordinary hubs.

Now, connected to the 2 x 2950 are a router each.

We want connection via the 2 routers to go through the 2950 via the 1GB Link.

How can I effect this?

ankurbhasin Wed, 04/05/2006 - 08:24

Hi Friend,

Ohh I think I already answered this in your another post.

Anyways you just need to configure intervlan routing on cat6k and 3550 switch so that you can route traffic from vlan 1 coming from router to 2950 switch to cat6k and on 3550 on remote side can be routed to vlan 211 and can be passed from one site to another.

Also is it not possible for you to configure trunk between cat6k and 3550 switch which allow vlan 1 and it will be a very sweet and simple setup.

Check how to configure inter vlan routing on layer 3 switches

http://www.cisco.com/warp/public/473/howto_L3_intervlanrouting.html

HTH, if yes please rate the post.

Ankur

londint Wed, 04/05/2006 - 08:53

Thanks Ankur

If I configre the link for trunk instead of access vlan 1 on the Cat6k and C3550, that means I will have to configure on the link vlans allowed or pruned on the Cta6k and on the C3550 as I only have access to these on our site.

Thanks

ankurbhasin Wed, 04/05/2006 - 08:58

Hi Friend,

I am asking to have trunk between cat6k and 3550 switch and allow vlan 1 also with vlan 211 so that vlan 1 can be passed from router to 2950 to cat6k and then on the remote side and if trunk is not possile then the only solution is to have inter vlan routing on 3550 and cat6k sitch and have a defaut route pointing to vlan 211.

HTH, if yes please rate the post.

Ankur

londint Wed, 04/05/2006 - 09:10

Thanks you, I have since set up trunking on the Cat6k and C3550.

But now I have the following

Port Mode Encapsulation Status Native vlan

8/15 on dot1q trunking* 1

Also on the Cat6k, can I do a

clear trunk 8/15 2-210,212-1005, 1025-2094

as the routers only need the Vlan 211 to communicate?

Correct Answer
ankurbhasin Wed, 04/05/2006 - 09:15

Hi Friend,

Yes you can do that and now you router is not taking via vlan 211 but they are simply connected from one router to another via vlan 1.

router--vlan 1(2950)vlan 1(cat6k)trunk(3550)--vlan 1(2950)vlan 1--router.

Hope you goy my point now.

HTH, if yes please rate the post.

Ankur

londint Wed, 04/05/2006 - 09:27

Thank you s very much.

when I do a show trunk on the Cat6k it comes up with the following

8/15 on dot1q trunking* 1.

I have tried loking for this on the cisco website but no answer.

Please what does the status trunking* mean?

Thanks

ankurbhasin Wed, 04/05/2006 - 09:36

Hi Friend,

AFAIK it is native vlan mismatch. Cause your cat6k is having native vlan as 211 and when you might have configured trunk on 3550 the dfeault native vlan will be 1.

So try changing native vlan on 3550 and see if * goes off.

switchport trunk native vlan 211

Config this under the interface which is configured for trunk on 3550 switch.

HTH, if yes pleas rate all post.

Ankur

londint Wed, 04/05/2006 - 09:50

Thanks

The native vlan on the cat6k is 1 and on the 2950 is also 1 as well as the 3550.

What else can I look for.

Thank for your help

ankurbhasin Wed, 04/05/2006 - 19:42

Hi Friend,

I am sorry for my last information.

Console> show trunk

* - indicates vtp domain mismatch

So if you see * in sh trunk command in your cat6k switch that means there is a VTP domain name mismatch between the trunks.

Now you have configured trunk between cat6k and 3550 switch so you can check the vtp domain names and if you want you can have a common domain name but as a matter of fact it will not have any problem even if you have a domain mismatch cause you are not using VTP in your network and you only have 2 vlans (vlan 1 and vlan 211) so you should no be concerned about VTP domain mismatch.

Incase if you want to see the VTP domain names on both the switch (cat6k and 3550) use this command

For cat6k

show vtp domain

For 3550

show vtp

HTH, if yes please rate all helpfull post.

Ankur

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