ProCurve Series 2300 and 2500 Switches Release Notes

189
Enhancements in Release F.02.02
CDP
Using the example in figure 87:
The CDP Neighbor table for switches "A" and "B" would appear similar to these:
Switch A:
Switch B:
Figure 88. Example of Viewable CDP Neighbor Table for Switches "A" and "B in Figure 87
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. (See the relationship between switches A, B, and C in figure 87.) 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.
Table 15. How Devices Handle Incoming CDP Packets
Non-CDP devices (that is, devices that are not capable of running CDP) are transparent to CDP
operation. However, an intervening CDP-aware device that is CDP-disabled is not transparent. For
example, in figure 87 (page 188), "B", "D", and "E" are not CDP neighbors because "D" (the intervening
CDP-disabled switch) does not forward CDP packets; i.e. is not transparent to CDP traffic. (For the
same reason, switch "E" does not have any CDP neighbors.)
Status of Device Receiving
a CDP Packet
Action of Receiving Device
Running CDP Stores neighbor data in CDP Neighbor table. Does not forward CDP packet.
CDP Disabled Drops CDP packet. There is no CDP Neighbor table and no CDP neighbor data is stored.
No CDP Capability Forwards CDP packet out all ports except the port on which the packet was received.
Router Running CDP Stores neighbor data in CDP Neighbor table. Does not forward CDP packet.
Router with CDP (1) Disabled
or (2) Not CDP-Capable
Drops CDP packet.
(Note that no CDP devices appear on port 5, which is connected to a device on which CDP is present, but disabled.)