Vlans between 2 routers and 2 switches config help

Unanswered Question
Feb 23rd, 2010

Hi,

I just can't seem to understand this. I have 2x switches and 2x routers.

R1, has vlan 10, 20, and 50 configured on it.

R2, has vlan 30 only on it

S1 is trunked to R1 and carries vlan 20 for switch management, and vlan 50 for servers

R2 is trunked to R1 and carries vlan 10 only

S2 is trunked to R2 and carries vlan 30 for switch managmement

Question, How do i pass vlan 50 to R2, and then to S2?

Please provide config examples from R1, R2, S2. I can't seem to figure this out at all.

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Jon Marshall Tue, 02/23/2010 - 09:07

gskhanna wrote:

Hi,

I just can't seem to understand this. I have 2x switches and 2x routers.

R1, has vlan 10, 20, and 50 configured on it.

R2, has vlan 30 only on it

S1 is trunked to R1 and carries vlan 20 for switch management, and vlan 50 for servers

R2 is trunked to R1 and carries vlan 10 only

S2 is trunked to R2 and carries vlan 30 for switch managmement

Question, How do i pass vlan 50 to R2, and then to S2?

Please provide config examples from R1, R2, S2. I can't seem to figure this out at all.

You need to make your interconnections trunk links and allow vlan on the trunk link. So S1 -> R1, R1 -> R2, R2 -> S2 all need to be configured as trunk links.

Edit - i was assuming your routers were actually L3 switches. If they are actually routers then you can't do this because you can't route to the same vlan. You could look at bridging or L2TPv3 to allow you to extend a L2 vlan across a routed network.

Can you confirm what devices your routers are ?

Jon

gskhanna Tue, 02/23/2010 - 19:49

S1 layer2 switch

R1 6509 sup720 router

R2 6509 sup720 router

S2 layer2 switch

I guess my problem is in the understanding that since r1 has vlans on it, and r2 has vlans on it, i don't want them to share all the vlans from each other, only a few such as vlan 50.


Besides that, the other point is to make a vlan backhaul between s1 and s2 for a user. R1 and R2 are connected via darkfiber 10km over 10gb-lr ethernet.

Jon Marshall Wed, 02/24/2010 - 00:59

gskhanna wrote:

S1 layer2 switch

R1 6509 sup720 router

R2 6509 sup720 router

S2 layer2 switch

I guess my problem is in the understanding that since r1 has vlans on it, and r2 has vlans on it, i don't want them to share all the vlans from each other, only a few such as vlan 50.


Besides that, the other point is to make a vlan backhaul between s1 and s2 for a user. R1 and R2 are connected via darkfiber 10km over 10gb-lr ethernet.

You can control which vlans are "shared" by using the "switchport trunk allowed vlan ....." command. So you would allow on the vlans you wanted across the trunk links. See this link for details -

http://www.cisco.com/en/US/docs/ios/interface/command/reference/ir_s7.html#wp1014809

Jon

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