bridging SNA 3550 2950

Dear all,

I'm trying to configure a bridge for non-routed protocols between two VLANs (bridge is to be used by SNA), but up to now I've failed. I read a lot of docs, but still can't figure it out.

Consider the following topology:

Client --- 2950 --- 3550 --- Mainframe

The client is on VLAN 2 while Mainframe is on VLAN 1. The VLANs are on different IP segments, so we are routing between the VLANs (using the 3550). Using TCP/IP, everything works fine but SNA doesn't go through.

I planned on creating a bridge, puting VLAN 1 and VLAN 2 on the same bridge group.

In the 3550, I issued: (config)# bridge 1 protocol vlan-bridge (config)# int vlan 1 (config-if)# bridge-group 1 (config-if)# exit (config)# int vlan 2 (config-if)# bridge-group 1

Looked simple...but those commands don't exist in the 2950, and so I'm not even sure now that this config was the good one to be done.

Any hint ? There are a lot of very complex docs out there, but I just want to do a simple bridge for non-routed protocols.



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Sebastien Mazeau
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I am pretty sure that the 2950 doesn't do this.

Software bridging is a function carried out by traditional Cisco routers. The "routing" switches do it to some extent too.

The 2950 has no "routing" fucntionality at all.

Check the 2950 "Command Reference".

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I would have thought that switches are more concerned with bridging than routers, as bridging is layer 2...damn.

Thanks for your answer.


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Reply to
Sebastien Mazeau

Hi Sebastion,

Just a guess here, but for the 2950 the VLAN is a Layer 2 entity only, it has no layer 3 properties, so you would need to BRIDGE, not Route between the 2 switches to get traffic there, because the 2950 doesn't have routing capability.

We use DLSW to Route SNA traffic, but DLSW operates at Layer3 and is not available on 2950's.

A VLAN is "local" only to each switch, so the gap bewteen the 2 Switches needs to be bridged as well to get the Layer 2 stuff between them without using Layer 3. Withot destroying the Layer 3 environment, if you have 2 ports free at each end, PLUS a spre link available (I hope they are the same cabinet........;-)) you could bridge everything for those ports........;-)

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As a follow-up, I tried the exact same thing using two 3550s, and it worked like a charm, I didn't even have to enter any additional command.


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