From: Scott F. Robohn (sfr@xxxxxxxxxxxxxx)
Date: Mon Jul 31 2000 - 22:18:22 GMT-3
Brian,
One of my students passed this link on ODR to me last week:
http://www.cisco.com/warp/public/105/39.html
Scott
Brian Edwards wrote:
>
> Anyone have any experience with this? It seems as though it uses CDP. What
> is the advantage over RIP? Is this a 12.1 feature? Might be a nice tool to
> use in the lab if they limit you from using other protocols.
>
> /Brian
>
> -----Original Message-----
> From: Simon Baxter [mailto:Simon.Baxter@au.logical.com]
> Sent: Monday, July 31, 2000 4:33 PM
> To: Kevin Baumgartner; Mark Lewis
> Cc: ccielab@groupstudy.com
> Subject: RE: IRB (I thought I understood it until...!)
>
> 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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