Gigabit Switch Router (GSR) support bridging?

Unanswered Question
Jul 14th, 2009

Hi guys,

I just found this on FAQ, do recent IOS support bridging for GSR?



I have this problem too.
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chinkevi_2 Tue, 07/14/2009 - 21:40

the short answer is no.

gsr is ip and cef switch only. You may find unsupport features with command parsers still exist but they are not supported.

GSR was designed to purely switch traffic as P router, though PE feature set was added afterward.

jeffersoncbriones Fri, 07/17/2009 - 18:42

Hi chinkevi,

I saw also this on the cisco website, how can i pass multivlan then with gsr? Is there a possibility? Below is my scenario.


I want my vlans from my switch to have their gateway at the 7206Router.



Giuseppe Larosa Sat, 07/18/2009 - 04:46

Hello Jeff,

you can use EoMPLS to take all vlans to c7206.

c7206 needs:

one backbone interface with mpls enabled

one interface as exit point of EoMPLS service

one interface with subinterfaces to provide L3 services to selected vlans

you need also an external switch on the C7206 site/side to do the trick.

Be aware that C7206 will be the bottleneck.

Hope to help


jeffersoncbriones Sat, 07/18/2009 - 06:31

Hi Guiseppe,

So i need another switch between my 7206 and GSR? my aim really is to make the GSR somewhat like a bridge but since its not capable. So my switch vlans gateway is the 7206 but with GSR in between i cant do that, EoMPLS works for me?



Giuseppe Larosa Sat, 07/18/2009 - 10:54

Hello Jeff,

the suggested setup is:

switch1 --- EoMPLS access-link GE --- GSR

GSR --- MPLS link (can be pos or serial) -- C7200---eompls-int -- switch2

C7200 --- routed link --switch2

you need a loopback on each device advertised by a routing protocol like OSPF.

that is used as MPLS router-id and for LDP session between the two to setup the EoMPLS service.

It may be simpler if GSR can do local switching with EoMPLS on two loopbacks defined on it. But I'm not sure of this.

Notice that EoMPLS can be vlan based and on the same interface you can have L3 subinterfaces used as L3 MPLS VPN access links, EoMPLS L2 access links, and even backbone mpls enabled links.

We tested this on 3GE engine2 linecard for GSR with good results and no performance penalty.

Hope to help


jeffersoncbriones Sat, 07/18/2009 - 18:01

Hi Giuseppe ,

Thank you for these very informative suggestions, i have to research on it now. Another thing, how bout creating a tunnel from a client router to the 7206 and seeing the GSR bypassed, is this possible.



Create tunnel bet. ClientRouter to 7206Router




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