[cisco-bba] About converting from IRB to RBE

[Mark E. Mallett]

Related to my other message: I had a couple of nit questions about
converting an IRB configuration to an RBE one.  Given the IRB
configuration on a Cisco 7200 like:

bridge irb
!
interface BVI10
 description DSL BVI
 mac-address 0000.xxxx.yyyy
 ip address 192.168.10.1 255.255.255.0
 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


I had tinkered a little and tried this:

interface atm1/0
 mac-address 0000.xxxx.yyyy
!
interface atm1/0.301 point-to-point
 description Verizon DSL RBE
 range vz-dsl pvc 1/301 1/303
  exit
 atm route-bridge ip
 ip address 192.168.10.1 255.255.255.0
 ip helper-address some address
 no ip proxy-arp
 ip route-cache same-interface
 no ip mroute-cache

which is pretty much straight out of various Cisco examples.
Right off the bat I got complaints about duplicate IP addresses.
It seems that the "range" statement creates clones of the PVC
configurations, IP address and everything, causing conflicts.
The first PVC did appear to work, but of course the two clones
did not.

I had wanted to avoid putting the IP assignment on a loopback
interface for various reasons.  On some other list I saw a example
where somebody kept their old BVI interface from the IRB
configuration, and configured the RBE interfaces as unnumbered with
reference to the BVI interface.  That seemed a little perverse, but I
tried it:

interface BVI 10
 ip address 192.168.10.1 255.255.255.0
!
interface atm1/0.301 point-to-point
 description Verizon DSL RBE
 range vz-dsl pvc 1/301 1/303
  exit
 atm route-bridge ip
 ip unnumbered BVI10

However none of the PVCs worked (that is, none of the customers could
be reached, and no ARP entries were created for them.)  Another
thought is to specifically configure each PVC (not using "range"),
give the first one an IP address configuration, and configure the
others as unnumbered with reference to the first PVC.  But that seems
tacky and unstable.

Any thoughts?  Mostly I am sending this out while I am waiting for the
next window in the wee hours when I can do a little more trying.
But if anybody is out there and has comments, I'd be interested in
hearing..

Yours,
-mm-