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12-22
Configuring for Network Management Applications
CDP
Monitoring and Managing
the Switch
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 12-12-13 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".
Figure 12-13. 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 "A") expires. Until then, the show cdp
neighbors
command continues to list switch "A" on port B5 of switch "B".)
Syntax: [no] cdp enable <[ethernet] port-list>
For example, to disable CDP on port A1 of a Switch 4108GL:
Switch 4108GL(config) no cdp enable a1
Changing the Transmission Interval for Outbound CDP Packets. The
default interval the switch uses to transmit CDP packets describing itself to
other, neighbor devices is 60 seconds. This command changes the interval.
Syntax: cdp timer <5 . . 254>
Switch "A"
CDP Enabled on Port A1
CDP Neighbor Table
Port | Data
------|------------------
A1 | Switch "B" data
Switch "B"
CDP Enabled on Port B5
CDP Neighbor Table
Port | Data
------|------------------
B5 | Switch "A" data
CDP Enabled on both
ends of the link between
"A" and "B".
Port A1
Port B5
Switch "A"
CDP Disabled on Port A1
CDP Neighbor Table
-Empty for port A1-
Switch "B"
CDP Enabled on Port B5
CDP Neighbor Table
- Empty for Port B5 -
CDP disabled on port A1
of switch "A" (but
enabled on port B5 of
switch "B".
Port A1
Port B5