12-15
Configuring for Network Management Applications
CDP
M
oni
to
rin
g
and
M
ana
gi
ng
th
e
Sw
itc
h
Figure 12-6. Example of Outgoing CDP Packet Operation
Incoming CDP Packets
When a CDP-enabled Switch 4108GL 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 Switch 4108GL reviews the
list of CDP neighbor entries every three seconds, and purge any expired
entries.
Non-CDP devices such as some hubs and other devices that do not have CDP
capability are transparent to CDP operation. (Other hubs are CDP-aware, but
still forward CDP packets as if they were transparent to CDP operation. See
“CDP-Capable Hubs” on page 28.) However, an intervening CDP-aware device
that is CDP-disabled is
not
transparent. For example, in figure 12-7, the CDP
Switch "A"
Switch 4108GL with
CDP Running and
Forwarding CDP
Packets to Down-
stream Devices
Switch "B"
CDP-Aware
Switch with
CDP Running
Switch "C"
CDP-Aware
Switch with
CDP Disabled
Router "Y"
With CDP
Disabled or
Nonexistent
Device "Z"
Hub or Other
Non-CDP
Device
Router "X"
With CDP
Running
Accepts, but does
not
forward CDP
packets describing Switch "A". Also
transmits CDP packets describing itself
(Switch "B") 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.
Drops CDP packets describing Switch
"A". Also, does not transmit any CDP
packets describing itself (Switch "C").
Accepts, but does
not
forward CDP
packets from Switch "A". Also transmits
CDP packets describing itself (Router "X")
out all ports.
Summary of Contents for ProCurve 4108gl Bundle
Page 1: ...hp procurve switch 4108gl management and configuration guide www hp com go hpprocurve ...
Page 2: ......
Page 40: ...2 16 Using the Menu Interface Where To Go From Here Using the Menu Interface ...
Page 154: ...8 24 Time Protocols SNTP Messages in the Event Log Time Protocols ...
Page 350: ...14 44 Port Based Virtual LANs VLANs and GVRP GVRP Port Based Virtual LANs VLANs and GVRP ...
Page 383: ...16 13 Spanning Tree Protocol STP How STP Operates Spanning Tree Protocol STP ...
Page 384: ...16 14 Spanning Tree Protocol STP How STP Operates Spanning Tree Protocol STP ...
Page 442: ...18 30 Troubleshooting Restoring a Flash Image Troubleshooting ...
Page 466: ...B 6 MAC Address Management Determining MAC Addresses MAC Address Management ...
Page 470: ......
Page 481: ...Index 11 Index write memory effect on menu interface 2 13 X Xmodem OS download A 6 ...
Page 482: ......