From: Kevin Baumgartner (kbaumgar@xxxxxxxxx)
Date: Mon Jul 31 2000 - 21:13:17 GMT-3
The bridge 1 route ipx, bridge 1 route ip, etc. just tells it to do irb for the
se
protocols. (actually I believe if you do bridge 1 irb, it may automatically do
bridge 1 route ipx and bridge 1 route ip) Still need to put the IPX or IP netw
ork
address on the BVI interface so that this network is routed. Otherwise this
bridged network will not be routeable.
Kevin
At 09:32 AM 8/1/00 +1000, you wrote:
>I guess the idea is that traffic bridged from the r1/r7 lan is bridged over
>the r1/r5 serial link and then selectively (with bridge 1 route ipx, brisge
>1 bridge ip etc) routed (or bridged) from the BVI on r5.
>
>I haven't built it, but it sounds straight forward enough??
>
>
>Simon
>
>
>-----Original Message-----
>From: Kevin Baumgartner [mailto:kbaumgar@cisco.com]
>Sent: Tuesday, August 01, 2000 3:54 AM
>To: Mark Lewis
>Cc: ccielab@groupstudy.com
>Subject: Re: IRB (I thought I understood it until...!)
>
>
>At 04:44 PM 7/31/00 +0000, you wrote:
>
>
> >Hi people,
> >
> >This is a question about lab 8, so if you haven't done it yet, avert your
>eyes now !
> >
> >
> >
> >On lab 8b, you have to configure bridging between the ethernet segment
>connected to r1 & r7 and the serial connection between r1 & r5. So far so
>good. However, then you are required to configure IRB on r5. Why? I was
>under the (obviously mistaken) impression that with IRB you use it with
>multiple interfaces in a bridge-group and it provides routing (ref. Cisco
>LAN Switching (CiscoPress)). There's only one interface in the bridge group
>on r5. Is this something to do with encapsulation ??!!
>
> IRB allows routing between and routed network and a bridged network. This
>can be IP, IPX, Appletalk and I believe a few other protocols.
>The key part about using IRB is that you need to create what is called a
>"BVI" interface. This is similar to a physical interface and here you
>configure either IP address, IPX, Appletalk for the bridged network. So in
>lab 8b the IPX network that is defined on r7 has to be define also
>on the BVI interface on r5. The great thing now is that you can route
>between the bridged network and the rest of the IPX networks on the
>ethernet side of r5.
>
> Just defining bridge-groups on r5 doesn't give you IRB. You need to
>define the BVI interface and apply the network address to it.
>The easiest way to thing of why you would use IRB is to see what happens if
>you are just using bridge-groups. It's a competely flat network.
>Basically one big network for everyone. This is not the really world. There
>are going to be a number of subnetted networks already and you
>need to somehow put your bridged network as part of this subnetted network.
>This is how IRB comes into play.
>
> Kevin
>
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