Incoming Cdp Packets - HP ProCurve 6400cl Series Management And Configuration Manual

Configuring for Network Management Applications
CDP on the Series 5300xl Switches
Switch "A"
Series 5300xl Switch
with CDP Running
Figure 14-22. Example of Outgoing CDP Packet Operation
14-56
Switch "B"
CDP-Aware
Switch with
CDP Running
Switch "C"
CDP-Aware
Switch with
CDP Disabled
Router "X"
With CDP
Running
Router "Y"
With CDP
Disabled or
Nonexistent
Device "Z"
Hub or Other
Non-CDP
Device

Incoming CDP Packets

When a CDP-enabled Series 5300xl switch receives a CDP packet from another
CDP device, it enters that device's data in the CDP Neighbors Table, along with
the port number where the data was received (and does not forward the
packet). The switch also periodically purges the table of any entries that have
expired. (The hold time for any data entry in the switch's CDP Neighbors Table
is configured in the device transmitting the CDP packet, and cannot be
controlled in the switch receiving the packet.) A Series 5300xl switch reviews
the list of CDP Neighbor entries every three seconds, and purges any expired
entries.
Non-CDP devices such as some hubs and other devices that do not have CDP
capability, as well as CDP-capable devices with CDP disabled, are transparent
to CDP operation. (Some hubs are CDP-aware, but still forward CDP packets
Accepts, but does not forward CDP
packets describing Switch "A". Also
transmits CDP packets describing itself
(Switch "B") out all ports.
Forwards CDP packets from Switch "A"
out all ports (except the port receiving the
packets from "A") without any awareness
of CDP operation.
Accepts, but does not forward CDP
packets from Switch "A". Also transmits
CDP packets describing itself (Router "X")
out all ports.
Drops CDP packets describing Switch "A".
Also does not transmit any CDP packets
describing itself (Router "Y").
Forwards CDP packets from Switch "A" out
all ports (except the port receiving the
packets from "A") without any awareness
of CDP operation.