HP ProCurve 6400cl Series Management And Configuration Manual page 354

Configuring for Network Management Applications
CDP on the Series 5300xl Switches
Switch A:
Switch B:
Figure 14-24. Example of Viewable CDP Neighbors Table for Switches "A" and "B" in Figure 14-20
Table 14-3. How Devices Handle Incoming CDP Packets
Status of Device Receiving
a CDP Packet
Running CDP
CDP Disabled
No CDP Capability
Router Running CDP
14-58
Using the example in figure 14-23, the CDP Neighbors Table for switches "A"
and "B" would appear similar to these:
Thus, based on the CDP packets it receives, each CDP device maintains a per­
port data entry for each of its neighbors that are running CDP, but not for other
CDP devices that are accessible only through a CDP Neighbor; that is, a device
that is running CDP. (See the relationship between switches A, B, C, and E in
figure 14-23.) In other words, a CDP device will have data on its immediate
CDP Neighbors (including those reached through a device that is transparent
to CDP), but not to other CDP devices in the network.
Action of Receiving Device
Stores neighbor data in CDP Neighbors Table. Does not forward CDP packet.
Forwards CDP packet out all ports except the port on which the packet was received.
There is no CDP Neighbors Table and no CDP Neighbor data is stored.
Forwards CDP packet out all ports except the port on which the packet was received.
Stores neighbor data in CDP Neighbors Table. Does not forward CDP packet.
Non-CDP devices (that is, devices that are not capable of running CDP) and
CDP-disabled devices are transparent to CDP operation. For example, in
figure 14-23 (page 14-57), "B" and "E" are CDP Neighbors because "D" (the
intervening CDP-disabled switch) forwards CDP packets; i.e. it is transparent
to CDP traffic.