From: Rob Barton (rob.barton@xxxxxxxxx)
Date: Fri Mar 31 2000 - 13:09:59 GMT-3
I ran into this kind of problem a while ago myself. I think Dave has it right
on. For bridging to work, all interfaces in the bridge group need to be on the
same subnet. I believe the reason is that when a bridge forwards an Ethernet
frame, it will first flood it out of all interfaces which belong to that
particular subnet. If your serial interface doesn't have an ip address on the
subnet, the bridge won't consider that interface as part of the same LAN. This
is the same reason your PC needs a default gateway - so the computer knows whic
h
interface to send the Ethernet frames out of.
- Rob
David H. Brown wrote:
> Chuck,
>
> From your description, I think you have this:
>
> R1 -- Eth -- R2 -- FRAME -- R3 -- Eth -- R4
> E0 E0 S0 S0 E0 E0
> .1 .2 .12 .13 .3 .4
> 192.168.1.X /24
>
> I duplicated your scenario, and also turned off IP Routing on all routers.
> All are in the same bridge group and same subnet; I turned on debug IP
> packet, and the ping from .2 to .4 resulted in 'encapsulation failed'. When
> I added an IP address on R2-S0 (.12), the pings began to work. It appears
> that there needs to be an IP address on each interface on the router for the
> ping to reach any interface on that router. When I remove the .12 from
> R2-S0, I can no longer ping from .4 to .2
>
> I hope this is clear - but in summary, in order to ping from R1 to E0 on R3,
> S0 of R3 must have an IP address. Now, can someone else fill in the theory
> as to why this is?
>
> David
> (2nd attempt coming soon)
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> Charles Wolfe
> Sent: Thursday, March 30, 2000 6:57 PM
> To: ccielab@groupstudy.com
> Subject: bridging
>
> Ladies and Gentlemen,
>
> My setup is as follows. R1 to R2 is connected by ethernet. R2 to R3 is
> connected by frame-relay. R3 to R4 is connected by ethernet.
> I have bridging activated on all interfaces and have the "frame map bridge"
> command configured on the fr interfaces.
> I have an ip address on R1 ethernet interface and R4 ethernet interface. I
> can ping them no problem from both ends.
> When I add an ip address to one of the other interfaces I cannot ping it. I
> would think that I should be able to do this since all the interfaces belong
> to the same bridge-group.
> I have tried various irb configs but I still don't think I need irb to
> accomplish this.
> Any help in understanding this is greatly appreciated.
>
> Thanks
> -Chuck
>
This archive was generated by hypermail 2.1.4 : Thu Jun 13 2002 - 08:23:07 GMT-3