CDP Neighbour show itself

Unanswered Question
Dec 1st, 2009

Hi All,


Could someone please help me, I have a router connected to a BT (British Telecoms) LES circuit via interface Gig0/0/0. The problem I'm having is when I do show cdp neighbour it shows itself and not the switch on the other end. Local router is W-UK-WL-ER3002-ISP-02 and the remote switch is SW-TCHX-AD4



W-UK-WL-ER3002-ISP-02#sho 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
W-UK-WL-ER3002-ISP-02.westfield-london.c
                 Gig 0/0/0          179         R S I     2851      Gig 0/0/0
W-UK-WL-ER3002-OUTDMZ-02
                 Gig 0/0            150          S I      WS-C3750G Gig 1/0/1

However on the switch end (SW-TCHX-AD4) when I do sho cdp neighbour I do see the router (W-UK-WL-ER3002-ISP-02)


SW-TCHX-AD4#sh cdp nei



Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge

S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone

Device ID Local Intrfce Holdtme Capability Platform Port ID

W-UK-WL-ER3002-ISP-02.westfield-london.c

Gig 5/10 141 R S I 2851 Gig 0/0/0








Has anyone ever had such a problem?

Thanks

Brett

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Giuseppe Larosa Tue, 12/01/2009 - 09:30

Hello Brett,

there is a L2 provider in the middle so all this can come from service provider equipment.


if SP devices are cisco they may need to be configured for L2 tunneling to carry CDP if provider is using 802.1Q tunneling.


in any case this is an emulation the real neighbor of your device is the service provider node.


Hope to help

Giuseppe

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