CDP information connected to access switch learned on CORE switch

sarabsin · ‎03-10-2016

Hello,

I am seeing CDP information of IP phones connected to one the access switches being learned on the CORE switch through the uplink port.

How is CDP going uplink thought it to be between the access port and ip phone only? I do see the Access switch in the cdp also.

Is this a bug ?

CORE01#show cdp neigh tengig 3/1/1 detail
-------------------------
Device ID: SEP588d09352018
Entry address(es):
IP address: 10.37190.36
Platform: Cisco IP Phone 6945, Capabilities: Host Phone Two-port Mac Relay
Interface: TenGigabitEthernet3/1/1, Port ID (outgoing port): Port 1
Holdtime : 172 sec
Second Port Status: Up

Version :
SCCP 9-4-1-3SR2

advertisement version: 2
Duplex: full
Power drawn: 3.840 Watts
Power request id: 9998, Power management id: 5
Power request levels are:3840 0 0 0 0
Management address(es):

-------------------------
Device ID: SEP8CB64FF6B586
Entry address(es):
IP address: 10.37.90.162
Platform: Cisco IP Phone 7965, Capabilities: Host Phone Two-port Mac Relay
Interface: TenGigabitEthernet3/1/1, Port ID (outgoing port): Port 1
Holdtime : 167 sec
Second Port Status: Up

Version :
SCCP45.9-4-2SR1-1S

advertisement version: 2
Duplex: full
Power drawn: 12.000 Watts
Power request id: 46470, Power management id: 3
Power request levels are:12000 0 0 0 0
Management address(es):

CORE01#show cdp neigh ten 3/1/1
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone,
D - Remote, C - CVTA, M - Two-port Mac Relay

Device ID Local Intrfce Holdtme Capability Platform Port ID
SEP588d09352018 Ten 3/1/1 128 H P M IP Phone Port 1
SEP8CB64FF6B586 Ten 3/1/1 123 H P M IP Phone Port 1
SEP203A07FD23EC Ten 3/1/1 163 H P M IP Phone Port 1
SEP8CB64FF622F2 Ten 3/1/1 176 H P M IP Phone Port 1
SEP8CB64FF624E7 Ten 3/1/1 134 H P M IP Phone Port 1
SEPE0D173E4E894 Ten 3/1/1 148 H P M IP Phone Port 1
SEP203A07FD325C Ten 3/1/1 174 H P M IP Phone Port 1
SEP203A07FD1EBC Ten 3/1/1 168 H P M IP Phone Port 1
SEP40F4ECEF7EBB Ten 3/1/1 172 H P M IP Phone Port 1
SEP8CB64FF6B40E Ten 3/1/1 126 H P M IP Phone Port 1
SEP2893FEA2597E Ten 3/1/1 137 H P M IP Phone Port 1
SEP8CB64FF62360 Ten 3/1/1 176 H P M IP Phone Port 1
SEP8CB64FF6B41B Ten 3/1/1 133 H P M IP Phone Port 1
SEP40F4ECEF865A Ten 3/1/1 126 H P M IP Phone Port 1
ACCESS SWITCH Ten 3/1/1 139 S I WS-C2960S Ten 1/0/1

sarabsin · ‎03-10-2016

Solution Found:

There is RSPAN configured on the access switch which sending traffic to CORE switch.

So it picks up the cdp packets from all source ports in RSPAN therefor all the IP Phones on those ports show up on Core switch.

Hope it helps.