[nsp] DSL customers seeing each other (fwd)

Mark E. Mallett mem at mv.mv.com
Thu Aug 14 15:04:23 EDT 2003


I asked a couple of related questions recently on the cisco-bba list.
One is about DSL users [not] seeing each other when they are aggregated
via IRB, and whether there is any q&d fix I can do to make that happen.
The other is about migrating from IRB to RBE (which will, probably,
solve the first question but not immediately).

I did get one enlightening response to the second question that helped
move me along a little (thank you!) but that was all.  I don't know
whether the cisco-bba list is not well populated or whether I am
asking stupid questions.  Hoping that it's the former more than the
latter I guess I will repeat here..


----- Forwarded message from "Mark E. Mallett" <mem at mv.mv.com> -----

> Subject: [cisco-bba] DSL customers seeing each other
> From: "Mark E. Mallett" <mem at mv.mv.com>
> Date: Wed, 6 Aug 2003 15:47:25 -0400
> To: cisco-bba at puck.nether.net
> Hi-
> I'm sure this has come up but I can't find it in various archives.  We
> have a Cisco 7200 with some DSL customers bridged on several ATM
> PVCs.  This is Verizon EAST- unlike some other providers where DSL
> connections each get their own PVC, while there are multiple PVCs
> quite a number of DSL connections are bridged on the same PVC, and the
> multiple PVCs are bridged together.  We're using an IRB
> configuration.  An issue is that individual customers can't see each
> other.  I can see ARP requests come in but since broadcasts are not
> propagated between customers they do not get answered.
> Short of going to RBE, is there a way to make the router respond to
> ARP requests on the DSL subnet(s) with its own MAC address?  Kind
> of like a proxy arp, but for the same subnet (like a local-proxy-arp
> in other environments).  I suspect the response is "use RBE"-- that's
> perfectly valid but I'm wondering if IRB mode can be made to do this
> as an interim fix.  (I have another set of questions about RBE for
> another message .. this list is too quiet anyway, no?)
> (BTW we have some other DSL aggregation with a CLEC on another ATM
> circuit- that CLEC intercepts the ARP requests on the DSL subnet(s)
> before they get to us and respond with our MAC address).
> The IRB configuration is something like:
> bridge irb
> !
> interface BVI10
>  description DSL BVI
>  mac-address 0000.xxxx.yyyy
>  ip address
>  no ip proxy-arp
>  ip route-cache same-interface
>  no ip mroute-cache
> !
> interface ATM1/0.1 multipoint
>  description DSL #1
>  no ip proxy-arp
>  pvc dsl1 1/301
>  !
>  bridge-group 10
>  bridge-group 10 spanning-disabled
> !
> interface ATM1/0.2 multipoint
>  description BA DSL #2
>  no ip proxy-arp
>  pvc dsl2 1/302 
>  !
>  bridge-group 10
>  bridge-group 10 spanning-disabled
> !
> ! repeat for other PVCs
> !

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