3400 CDP

[dtom]

We just installed a Cisco ME-3400EG switch at one of our sites.  A Cisco C3750X switch is connected to the 3400.  When we run the command CDP NEIGHBORS, the 3400 shows no devices.  We can access the 3750 via the 3400.  Also, when we run CDP NEIGHBORS on the 3750 we do not see the 3400 (but other devices are displayed).  How can we get CDP to display the devices on the 3400?  We have already tryed CDP RUN.

[Richard Burts]

You might try cdp enable on the interfaces.

What do you get as output to the commands show cdp and show cdp interface and show cdp traffic?

HTH

Rick

[dtom]

I cannot enter the command CDP ENABLE on the interface.  Also, here is what I get from the following commands:

try to configure cdp for interface gi0/2

===========================

ms-VANGPAO#conf t
Enter configuration commands, one per line. End with CNTL/Z.
ms-VANGPAO(config)#int gi0/2
ms-VANGPAO(config-if)#cdp enable
^
% Invalid input detected at '^' marker.

ms-VANGPAO(config-if)#

sh cdp

=====

ms-VANGPAO#sh cdp

Global CDP information:

        Sending CDP packets every 60 seconds

        Sending a holdtime value of 180 seconds

        Sending CDPv2 advertisements is enabled

ms-VANGPAO#

ms-VANGPAO#sh cdp int

FastEthernet0 is down, line protocol is down

  Encapsulation ARPA

  Sending CDP packets every 60 seconds

  Holdtime is 180 seconds

GigabitEthernet0/3 is down, line protocol is down

  Encapsulation ARPA

  Sending CDP packets every 60 seconds

  Holdtime is 180 seconds

GigabitEthernet0/4 is down, line protocol is down

  Encapsulation ARPA

  Sending CDP packets every 60 seconds

  Holdtime is 180 seconds

ms-VANGPAO#

ms-VANGPAO#sh cdp traf

CDP counters :

        Total packets output: 2, Input: 0

        Hdr syntax: 0, Chksum error: 0, Encaps failed: 0

        No memory: 0, Invalid packet: 0,

        CDP version 1 advertisements output: 0, Input: 0

        CDP version 2 advertisements output: 2, Input: 0

ms-VANGPAO#

ms-VANGPAO#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
ms-VANGPAO(config)#int gi0/2
ms-VANGPAO(config-if)#cdp enable
                       ^
% Invalid input detected at '^' marker.

ms-VANGPAO(config-if)#

sh cdp int

=======

ms-VANGPAO#sh cdp int
FastEthernet0 is down, line protocol is down
  Encapsulation ARPA
  Sending CDP packets every 60 seconds
  Holdtime is 180 seconds
GigabitEthernet0/3 is down, line protocol is down
  Encapsulation ARPA
  Sending CDP packets every 60 seconds
  Holdtime is 180 seconds
GigabitEthernet0/4 is down, line protocol is down
  Encapsulation ARPA
  Sending CDP packets every 60 seconds
  Holdtime is 180 seconds
ms-VANGPAO#

sh cdp traf

========

ms-VANGPAO#sh cdp traf
CDP counters :
        Total packets output: 2, Input: 0
        Hdr syntax: 0, Chksum error: 0, Encaps failed: 0
        No memory: 0, Invalid packet: 0,
        CDP version 1 advertisements output: 0, Input: 0
        CDP version 2 advertisements output: 2, Input: 0
ms-VANGPAO#

[Richard Burts]

I am not sure why cdp enable is not working on these interfaces, and assume that it is something on this platform that I am not familiar with. But the output that you post does help identify the issue. Each of the interfaces where the swtich is running CDP is in a down state. If the interfaces running CDP are all down then this explains why CDP is not showing any information.

So it seems to me that there are two issues here:

- how to enable CDP on the interface if cdp enable does not do it. So perhaps you can check interfaces Gig0/3 and Gig0/4 and see how CDP is enabled there. Then use this to enable CDP on other interfaces of the switch.

- why are these interfaces down? Can you verify whether anything is connected on these interfaces?

HTH

Rick

[dtom]

I think we found the answer.  The port-type was set to UNI.  We changed the port-type to NNI and when we run CDP NEIGHBORS command we were able to see downstream devices.  Do you see any issues with what we did here?

[javentre]

That sounds correct.  UNI ports don't support CDP.  It's documented here:

http://www.cisco.com/en/US/docs/switches/metro/me3400/software/release/12.2_50_se/configuration/guide/swcdp.html

"On the Cisco ME switch, CDP is enabled by default on network node interfaces (NNIs) and disabled by default on enhanced network interfaces (ENIs). It is not supported on user network interfaces (UNIs)."