From: Atif Awan (atifawan@xxxxxxxxxxx)
Date: Sun Dec 24 2000 - 18:22:54 GMT-3
Yup that sounds logical. Thanks a lot.
Regards
Atif
>From: "Thomas Alexander" <talexander1@austin.rr.com>
>Reply-To: "Thomas Alexander" <talexander1@austin.rr.com>
>To: "Atif Awan" <atifawan@hotmail.com>, <ccielab@groupstudy.com>
>Subject: Re: IPX bridging problem
>Date: Fri, 14 Jan 2000 22:24:50 -0600
>
>Atif,
>Let me put down my interpretation of Transparent Bridging.
>If we were to take a very simple examlple of 2-port transparent
>bridge. Eth LAN A------trans. brige------Eth LAN B
>The function here is to bridge Ethernet packets from
>from Ethernet LAN A to B or vice-versa. Now lets move
>this functionaly over a WAN. The function of the TB has
>been moved across 2 physical boxes, thus each box doing
>half of the function, even sometimes called a half-bridge:
> Eth LAN A------trans. brige-----trans. bridge------Eth LAN B
>The objective here again here is to transparently bridge from LAN
>A to LAN B. I hope the above explains why bridging over WAN goes
>in pairs. I have no idea why transparent bridging works when
>only router's WAN interface is configured for TB ? (Cisco bug or
>feature ??) But just to cross-check, I did the same configure but
>the WAN interfaces configured as PPP, where I could clearly
>see when I did a "SH INT" that BRIDGECP was not negotiated
>thru PPP, so router B would drop bridged packets originating from
>Ethernet interface with the message:
>Outbound bridge packet dropped, BNCP state is Listen
>This proves the point that bridging should be enable on both sides
>of a WAN link. Again, a more common configuration would be
>if the TB would be configured to bridge remote LANs.
>But with IRB enabled, the BVI interface becomes the kind of
>virtual LAN interface. Again, with IRB, BVI is a routed interface, so
>traffic coming into BVI may come bridged and then gets routed
>to other IPX networks connected to router C or vice-versa.
>
>Hope this helps.
>
>Thomas Alexander
>
>
>----- Original Message -----
>From: "Atif Awan" <atifawan@hotmail.com>
>To: <talexander1@austin.rr.com>; <ccielab@groupstudy.com>
>Sent: Sunday, December 24, 2000 1:33 AM
>Subject: Re: IPX bridging problem
>
>
> >
> > Well definitely router B is the culprit in this case but why this odd
> > behaviour and why do you say that it is a requirement for WAN interfaces
> > that bridging should be enabled on both ends ?
> >
> > this is confsing .. i will try it with configuring IRB on Router_C but
>even
> > if it works there has to be a logical explanation for this anomaly in
>the
> > bridge's behaviour.
> >
> > Atif
> >
> > >From: "Thomas Alexander" <talexander1@austin.rr.com>
> > >Reply-To: "Thomas Alexander" <talexander1@austin.rr.com>
> > >To: "Atif Awan" <atifawan@hotmail.com>, <ccielab@groupstudy.com>
> > >Subject: Re: IPX bridging problem
> > >Date: Fri, 14 Jan 2000 17:03:53 -0600
> > >
> > >Atif,
> > >
> > >The problem is that no bridging in configured on Router_C.
> > >Briding on WAN usually goes in pairs, ie both sides of a WAN link
>should
>be
> > >configured for bridging. In your case, only routerB serial 0 is
>configured
> > >for bridging.
> > >I have done a quick test in my lab, and ofcourse there is no problem
>for
>a
> > >IPX/RIP
> > >traffic originating from rtr A as it gets bridged from Router B and
>gets
> > >forwarded to
> > >Router C. Router B since it has bridging enable on S0, will forward the
> > >bridged packet to Router C.
> > >I am not sure how Router C accepts the bridge packet, may be it can
>support
> > >both bridge and routed
> > >packets. But when IPX/RIP traffic orignates from Rtr C, RTR B is
>expecting
> > >a
> > >bridged packet, instead
> > >received a normal packet to be routed, and it drops the packets. This
>can
> > >be
> > >confirmed if you do a
> > >"show bridge verbose". Under Flood ports, you will see zero bridged
>packets
> > >as being received from
> > >Router C. If the connection to router C were to be Ethernet (or LAN)
>like
> > >router a, this would would just
> > > work fine. So for example:
> > > Router_A(et0/0) --- (etH0)Router_B(s0) ---
>(s1)Router_X---(eth0)Routerc
> > > IPX routing TB
> > >TB IPX routing
> > >
> > >The other option is to enable IRB on Router C, so that it bridges IPX
>on
> > >the
> > >serial
> > >interface to routerB and routes from all other interfaces.
> > >
> > >Hope this helps..
> > >
> > >Thomas Alexander
> > >
> > >----- Original Message -----
> > >From: "Atif Awan" <atifawan@hotmail.com>
> > >To: <ccielab@groupstudy.com>
> > >Sent: Saturday, December 23, 2000 10:06 AM
> > >Subject: IPX bridging problem
> > >
> > >
> > > >
> > > > i was working ipx ( my weak spot :) ) when i encountered a strange
> > >problem
> > > > that i cannot seem to solve. The relevant setup is like this :
> > > >
> > > > Router_A(ether0/0) --- (ether0)Router_B(serial0) ---
>(serial1)Router_C
> > > >
> > > > All the 3 routers are routing IP. Router_A and Router_C have ipx
>routing
> > > > turned on too but Router_B does not have ipx routing turned on.
> > >Router_A's
> > > > ethernet0/0 and Router_C's serial 1 both have the same IPX network
> > >number.
> > > > Router_B has bridge-group 1 statements on both ether0 and serial 0.
> > > >
> > > > IPX RIP routes from Router_A are seen successfully in the ipx
>routing
> > >table
> > > > of Router_C. However, updates from Router_C are not reaching
>Router_A.
> > >When
> > > > i turn on debugging on Router_C it says that it is broadcasting
>updates
> > >out
> > > > serial 1 but these never reach Router_A. I dont think i need IRB
> > >anywhere
> > > > here ... why is this happening that one way traffic is going through
> > > > successfully and the other way its not ??? Rest assured there are no
>IPX
> > > > access-lists anywhere ...
> > > >
> > > > TIA
> > > > Atif Awan
> > > >
> >
This archive was generated by hypermail 2.1.4 : Thu Jun 13 2002 - 08:26:10 GMT-3