From: Jonathan V Hays (jhays@jtan.com)
Date: Mon Jun 30 2003 - 17:45:11 GMT-3
All,
Joe is correct. But I misspoke when I brought up the 3550 and bridging,
since that is NOT what I am trying to do anyway. And I apologize if I
haven't made myself clear.
So let me clarify. ;-)
Below is an ASCII diagram for a DLSW lab scenario. You want to bridge
SNA and NetBIOS over the WAN between R2 and R4 using DLSW.
3550-fa0/2-[vlan2]-e0-R2-s0-WAN-s0-R4-e0-[vlan4]-fa0/4-3550
The ports R1-e0 and R3-e0 and have "bridge-group 1" configured and are
each physically plugged into a port on the 3550, with each port on a
separate VLAN. It is true that since I have no hosts to generate packets
I might just as well disconnect them from the switch and configure "no
keepalive" on the ethernet ports.
However, the point is that the 3550 switch is not bridging anything. If
I had a hosts plugged into vlans 2 and 4 the frames would be forwarded
to the routers by the 3550, bridged by the routers and forwarded across
the WAN using DLSW. In fact there are no SNA or NetBIOS frames being
generated on either vlan. Nonetheless, as soon as I configure
"bridge-group 1" on the ethernet ports of the routers, the 3550 starts
acting up by removing those ports from their respective vlans (and later
reinstating them for a few seconds before removing them again.). This
will happen even before I configure any dlsw commands.
If anyone has any light to shed on this, I'd love to hear from you.
Thanks.
Jonathan
-----Original Message-----
From: Joe Martin [mailto:jmartin@capitalpremium.net]
Sent: Monday, June 30, 2003 4:25 PM
To: boby2kusa@hotmail.com; Jonathan V Hays; ccielab@groupstudy.com
Subject: RE: bridging removes port from 3550 vlan
Bob,
I do not think you read the original question very carefully. He is NOT
trying to configure DLSW on the 3550. He is configuring DLSW on routers
attached to the 3550, and when he issues the bridge-group 1 command on
the
router interface attached to the 3550, the switch interface is removed
from
the vlan to which it was configured.
I think most of us are aware that you CANNOT configure DLSW on a 3550.
Jonathan, correct me if I am wrong.
HTH,
Joe Martin
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
boby2kusa@hotmail.com
Sent: June 30, 2003 12:48 PM
To: Jonathan V Hays; ccielab@groupstudy.com
Subject: Re: bridging removes port from 3550 vlan
Nope, the only bridging it supports is fall back bridging. It kind of
defeats the purpose of vlan when you end up bridging them anyway. Why
not
put them all in a single vlan?
Check the config guide on fall back bridging it might work for you.
----- Original Message -----
From: "Jonathan V Hays" <jhays@jtan.com>
To: <boby2kusa@hotmail.com>; <ccielab@groupstudy.com>
Sent: Monday, June 30, 2003 11:40 AM
Subject: RE: bridging removes port from 3550 vlan
Thanks for the response. However, IMHO this does not seem like an
adequate theory to explain the switch behavior. Before the 3550s we had
a Catalyst 2950 which did not produce this behavior. And certainly you
could say that the 2950 does not support DLSW, since there is no mention
of it in any of the 2950 documentation.
Part of the point of DLSW is that it encapsulates nonroutable protocols
so you can bridge over the WAN. Let's say there is an ethernet
connection in the middle of the WAN traversal route. How exactly does
the 3550 switch know that it is forwarding a DLSW packet? And at layer
2, why would it care? It should be just another frame.
And besides, usually the ports forwarding DLSW frames in our scenarios
are WAN ports (although this depends on the scenario). The ethernet
ports are generally just configured with "bridge-group 1" and in our lab
there is no workstation generating SNA or NetBIOS frames. Those ports
are connected to the 3550 and should be pretty quiet.
As I implied in my original post with "(or simple bridging)," we get the
same behavior if we configure simple bridging on several ethernet router
ports (e.g., "bridge-group 1" and "bridge 1 protocol ieee"). I'm sure
that the 3550 supports bridging.
Still mystified,
Jonathan
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
> Behalf Of boby2kusa@hotmail.com
> Sent: Monday, June 30, 2003 2:03 PM
> To: Jonathan V Hays; ccielab@groupstudy.com
> Subject: Re: bridging removes port from 3550 vlan
>
>
> That's because the 3550 doe snot support DLSW. I have
> learned through out
> the years reading CCO release notes that if it does not
> mention support on
> particular protocol it does not support it. If anybody else
> think this is
> not true they can chime in and provide proof.
>
>
> ----- Original Message -----
> From: "Jonathan V Hays" <jhays@jtan.com>
> To: <ccielab@groupstudy.com>
> Sent: Monday, June 30, 2003 9:35 AM
> Subject: bridging removes port from 3550 vlan
>
>
> > My lab study partner has a pair of catalyst 3550s running
> the latest EMI
> > image, (C3550-I5Q3L2-M), Version 12.1(13)EA1a.
> >
> > Whenever we configure DLSW (or simple bridging) the
> fastethernet 3550
> > switch ports connected to the DLSW-enabled routers are
> removed from the
> > configured VLAN. You can execute "show vlan" on the switch
> and the DLSW
> > ports are missing. Removing the DLSW configuration from the router
> > restores the port to the VLAN. It goes without saying, but
> I'll say it
> > anyway, we have tried various ports and rebooted switches
> and routers
> > but that does nothing to fix this problem.
> >
> > The Cisco Bug Toolkit did not give me any hits on this problem.
> >
> > Does anyone have any ideas on this one?
> >
> > Thanks,
> >
> > Jonathan
> >
> >
> >
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