CDP and DLSW+

From: Dan.Thorson@seagate.com
Date: Tue Oct 29 2002 - 20:15:26 GMT-3


I am curious if others have seen this: CDP passing through a DLSW link
transparently.... and if this is expected behavior....

Given
R1 is a 2514
   R1 interface E0 --> Cat3550 Fast0/1
   R1 interface S0 --> HDLC to R2 (crossover DCE/DTE)

R2 is a 3662
   R2 FE0/0 --> Cat3550 Fast0/2
   R2 S0/0 --> HDLC to R1 (crossover DCE/DTE)

The Cat3550 is running EMI code.
   Fast 0/1 --> default configuration (and so should be in Vlan 1)
   Fast 0/2 --> switchport access vlan 200

When you build a DLSW+ connection between R1/E0 and R2/FE0/0 the 3550
thinks that there is a cross-over cable between it's 0/1 and 0/2
interfaces, that is, a show cdp nei for the 3550's Fast0/1 will show itself
as the neighbor on Fast0/2!

R1:
     dlsw local-peer peer-id 77.77.77.1 promiscuous
     dlsw bridge-group 1
     !
     interface Ethernet0
      ip address 77.77.77.1 255.255.240.0
      bridge-group 1
     !
     interface Serial0
      ip address 155.1.1.1 255.255.255.0
     !
     bridge 1 protocol ieee

R2:
     dlsw local-peer peer-id 10.1.1.1
     dlsw remote-peer 0 tcp 77.77.77.1
     dlsw bridge-group 1
     !
     interface FastEthernet0/0
      ip address 10.1.1.1 255.255.0.0
      bridge-group 1
     !
     interface Serial1/1
      ip address 155.1.1.5 255.255.255.0
     !
     bridge 1 protocol ieee

========================================
Dan Thorson - Seagate Technology, LLC
desk +1 (952) 402-8293 fax +1 (952) 402-1007
SeaTel 8-402-8293
========================================



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