[cisco-bba] DSL customers seeing each other

Mark E. Mallett mem at mv.mv.com
Wed Aug 6 16:47:25 EDT 2003


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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