Configuring for Network Management Applications

CDP

Enabling or Disabling CDP Operation on Individual Ports. In the factory-default configuration, the switch has all ports enabled and transmit­ ting CDP packets. Disabling CDP on a port prevents that port from sending outbound CDP packets and causes it to drop inbound CDP packets without recording their data in the CDP Neighbors table. Suppose, for example, that switches “A” and “B” in figure 13-18(below) are running CDP, and that port A1 on switch “A” is connected to port B5 on switch “B”. If you disable CDP on port A1 of switch “A”, then switch “B” will no longer receive CDP packets from switch “A” and switch “A” will drop the CDP packets it receives from switch “B”.

CDP Enabled on both ends of the link between "A" and "B".

Switch "A"

 

Port A1

 

 

 

Switch "B"

CDP Enabled on Port A1

 

 

 

 

 

CDP Enabled on Port B5

CDP Neighbor Table

 

 

 

 

 

CDP Neighbor Table

Port Data

 

 

 

 

Port Data

 

 

 

Port B5

 

------ ------------------

 

 

 

 

 

------------------------

A1 Switch "B" data

 

 

 

 

 

B5 Switch "A" data

 

 

 

 

 

 

 

CDP disabled on port A1 of switch "A" (but enabled on port B5 of switch "B".

Switch "A"

 

Port A1

 

 

 

Switch "B"

CDP Disabled on Port A1

 

 

 

 

 

CDP Enabled on Port B5

CDP Neighbor Table

 

 

 

 

 

CDP Neighbor Table

-Empty for port A1-

 

 

 

 

- Empty for Port B5 -

 

 

 

Port B5

 

 

 

 

 

 

 

 

Figure 13-18. Example of Disabling CDP on an Individual Port

(The switch "A" entry in the switch "B" CDP Neighbors table remains until the cdp holdtime (time-to-live; set in switch "B") expires. Until then, the show cdp neighbors command continues to list switch "A" on port B5 of switch "B".)

Syntax: [no] cdp enable < [e] port-list >

For example, to disable CDP on port A1:

HPswitch(config) no cdp enable a1

13-35