Re: Extending network with double SDH link

epasqualotto · ‎10-09-2009

Hi all, I need to transparently extend my network with double point-to-point SDH link. Each link has his router 2801 for a total of 4 routers.

What I want to do is a bridge between ethernet and serial interfaces in each side and manage the two link with spanning-tree.

All work except the spanning-tree, so all link stay active and this cause a lot of network problem.

My sample conf:

controller E1 0/2/0

clock source free-running

channel-group 1 timeslots 1-31

!

bridge irb

!

interface FastEthernet0/0

no ip address

duplex auto

speed auto

bridge-group 1

!

interface Serial0/2/0:1

no ip address

bridge-group 1

!

interface BVI1

no ip address

!

Giuseppe Larosa · ‎10-09-2009

Hello Enrico,

configuration of LAN switches at the two sides is important too.

you need to verify that all ports on LAN switches are in the same vlan so that the two links are seen as being part of the same topology.

on routers add also

bridge 1 protocol ieee.

In this way you are using 4 routers as LAN extenders.

You may want to consider also L2TPv3, but I'm not sure it is supported on 2801.

see

http://www.cisco.com/en/US/docs/ios/12_3t/12_3t2/feature/guide/gtl2tpv3.html

this could allow you to use the routers also for routing.

Also consider a routed solution that it is the best for performance and broadcast control.

Hope to help

Giuseppe

epasqualotto · ‎10-09-2009

In the lab for me the two switch are one 2960 with two vlan.

Monday I will try with two indipendent device.

I don't know L2TPv3 but seems interesting.

I prefer a routed solution too but if I extend this lan transparently my customer don't touch his infrastructure/application. :)

Thanks Enrico.

Giuseppe Larosa · ‎10-10-2009

Hello Enrico,

>> In the lab for me the two switch are one 2960 with two vlan.

this is the reason why you couldn't see STP working well in your tests.

L2TPv3 is very handy if you need to provide both routed and bridging services.

Hope to help

Giuseppe

epasqualotto · ‎10-12-2009

Today I have tried using two indipendent switch but STP still not working.

How can I debug it?

P.S. I have make some tests using port-channel but don't work well too.

Thanks Enrico.

viyuan700 · ‎10-12-2009

Hi Enrico,

Do you have idea that you can do that over serial link. In my opinion, IRB can be done if you are using Ethernet ports which are carried over SONET/SDH not when it is carried over serial link specially over electrical E1/DS3 ports.