From: Ben Zheng (bzheng8989@yahoo.com)
Date: Mon Jan 22 2007 - 22:07:37 ART
R1 (C2600) and R2 (C2800) is back-to-back connected. CDP are enabled on both
routers
R1 can see CDP neighbor R2 properly
R1#sh cdp nei
Capability Codes:
R - Router, T - Trans Bridge, B - Source Route Bridge
S -
Switch, H - Host, I - IGMP, r - Repeater
Device ID Local Intrfce
Holdtme Capability Platform Port ID
R2 Fas 0/0
142 R S I Cisco 2811Fas 0/1
However, R2 cannot see the CDP
neighbor R1.
Turn on debug CDP on R1 and R2, it shows that R1 can sent and
receive CDP properly, but R2 can only sent CDP. R2 cannot receive the CDP from
the neighbor. The debug on R2 shows the checksum error in receiving CDP
packet:
*Jan 23 00:55:01.215: CDP-EV: Bad checksum in header
It can also be
confirmed from the output of sh cdp traffic on R2
R2#sh cdp traffic
CDP
counters :
Total packets output: 12, Input: 0
Hdr syntax: 0,
Chksum error: 12, Encaps failed: 0
No memory: 0, Invalid packet: 0,
Fragmented: 0
CDP version 1 advertisements output: 0, Input: 0
CDP version 2 advertisements output: 12, Input: 0
How can I make CDP on R2
work properly?
R2#sh run int fa0/1
Building configuration...
Current
configuration : 119 bytes
!
interface FastEthernet0/1
description Link to R1
ip address 10.12.1.2 255.255.255.0
duplex auto
speed auto
end
R1#sh run int
fa0/0
Building configuration...
Current configuration : 119 bytes
!
interface
FastEthernet0/0
description Link to R2
ip address 10.12.1.1 255.255.255.0
duplex auto
speed auto
end
Thanks,
Ben
This archive was generated by hypermail 2.1.4 : Thu Feb 08 2007 - 23:46:57 ART