[c-nsp] Converting ATM to VLAN

[Clayton Zekelman]

I have a situation where I have ATM PVC's coming in (Bridged RFC 1483) and 
need to convert it to a VLAN dot1q trunk.  I'm doing this for a handful of 
paths, as the ATM enabled router is not the router I need the path to end 
up on.  If it were, I'd likely do ATM RBE.

I do the following:

interface ATM0/0/0.48 point-to-point
  description MNS-191+B VLAN 48 IP Transit
  bridge-group 48
  pvc MNS-191+B 1/70
   ubr 12500
   encapsulation aal5snap
  !
!
interface FastEthernet0/0/0.48
  description MNS-191+B  IP Transit
  encapsulation dot1Q 48
  bridge-group 48
!
bridge 48 protocol ieee
bridge 48 route ip

For some reason, things don't work properly unless I add:

interface BVI48
  no ip address

Can anyone shed any light on why I need to add the BVI?  It *appears* to do 
nothing:

uacA1#show bridge 48 ver

Total of 300 station blocks, 281 free
Codes: P - permanent, S - self

BG Hash      Address      Action  Interface      VC    Age   RX count   TX 
count
48 5F/0   0005.5ea1.5f00 
forward  Fa0/0/0.48      -      0     885110     892382
48 CC/0   00d0.ffb5.cc00 
forward  ATM0/0/0.48     15     0     892633     884682

Flood ports (BG 48)          RX count    TX count
ATM0/0/0.48                       249         213
FastEthernet0/0/0.48              213         249

The strange thing is, when we cut over, it worked fine without the BVI for 
an hour or two, then the whole thing went down, and wouldn't come back up 
until I added the BVI.



---
Clayton Zekelman
Managed Network Systems Inc. (MNSi)
344-300 Tecumseh Rd. E.
Windsor, Ontario
N8X 5E8

tel. 519-985-8410
fax. 519-258-3009 


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