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How does CDP choice the IP of it's neighbor

I am hitting an interesting issue between my router and switch. When I do a show cdp nei det on my switch I see the public IP address of my router instead of the management IP address like I would expect. I can post parts of the configuration upon request.

Thanks,

Chris

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Community Member

Re: How does CDP choice the IP of it's neighbor

CDP by default uses the first interface in the configuration, typically the one with lowest index count (Fa0/0, for example). You can change this with the following command (if you are using an IOS router):

UC500(config)#cdp source-interface ?

  Async                      Async interface

  Auto-Template              Auto-Template interface

  BVI                        Bridge-Group Virtual Interface

  CDMA-Ix                    CDMA Ix interface

  CTunnel                    CTunnel interface

  Dialer                     Dialer interface

  Dot11Radio                 Dot11 interface

  FastEthernet               FastEthernet IEEE 802.3

  Integrated-Service-Engine  cisco integrated service engine module

  Lex                        Lex interface

  Loopback                   Loopback interface

  Multilink                  Multilink-group interface

  Null                       Null interface

  Tunnel                     Tunnel interface

  Vif                        PGM Multicast Host interface

  Virtual-Access             Virtual Access interface

  Virtual-Dot11Radio         Virtual dot11 interface

  Virtual-PPP                Virtual PPP interface

  Virtual-Template           Virtual Template interface

  Virtual-TokenRing          Virtual TokenRing

  Vlan                       Vlan IEEE 802.1q

  vmi                        Virtual Multipoint Interface

3 REPLIES
Community Member

Re: How does CDP choice the IP of it's neighbor

CDP by default uses the first interface in the configuration, typically the one with lowest index count (Fa0/0, for example). You can change this with the following command (if you are using an IOS router):

UC500(config)#cdp source-interface ?

  Async                      Async interface

  Auto-Template              Auto-Template interface

  BVI                        Bridge-Group Virtual Interface

  CDMA-Ix                    CDMA Ix interface

  CTunnel                    CTunnel interface

  Dialer                     Dialer interface

  Dot11Radio                 Dot11 interface

  FastEthernet               FastEthernet IEEE 802.3

  Integrated-Service-Engine  cisco integrated service engine module

  Lex                        Lex interface

  Loopback                   Loopback interface

  Multilink                  Multilink-group interface

  Null                       Null interface

  Tunnel                     Tunnel interface

  Vif                        PGM Multicast Host interface

  Virtual-Access             Virtual Access interface

  Virtual-Dot11Radio         Virtual dot11 interface

  Virtual-PPP                Virtual PPP interface

  Virtual-Template           Virtual Template interface

  Virtual-TokenRing          Virtual TokenRing

  Vlan                       Vlan IEEE 802.1q

  vmi                        Virtual Multipoint Interface

Community Member

Re: How does CDP choice the IP of it's neighbor

That worked perfectly!


Thanks!

Community Member

Re: How does CDP choice the IP of it's neighbor

Thanks for the info. What if we are hitting the same issue between 2 switches? Instead of the management vlan showing up we are seeing other layer 3 vlans that would not be accessable.

Thanks,

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