Configuring for Network Management Applications

CDP

Changing the Transmission Interval for Outbound CDP Packets.

Syntax: cdp timer < 5 . . 254 >

Changes the interval the switch uses to transmit CDP packets describing itself to neighbor devices. (Default: 60 seconds)

For example, if the switch’s transmit interval for CDP packets was set to a non-default value, you would use this command to reset it to one minute:

HPswitch(config) cdp timer 60

Changing the Hold Time (CDP Packet Time-To-Live) for a Switch’s

CDP Packet Information. This parameter is controlled in the transmitting switch, and applies to all outbound CDP packets the switch transmits.

Syntax: cdp holdtime < 5 . . 254 >

Changes the hold time for the switch’s CDP packet informa­ tion in the CDP Neighbors table of another CDP-aware device. (Default: 180 seconds; Range: 10 - 255 seconds.)

For example, to configure a switch’s outbound CDP packets to live for one minute in the CDP Neighbors table of neighboring CDP devices:

HPswitch(config) cdp holdtime 60

Effect of Spanning Tree (STP) On CDP Packet

Transmission

If STP has blocked a port on the switch, that port does not transmit CDP packets. However, the port still receives CDP packets if the device on the other end of the link has CDP enabled. Thus, for example, if switch "A" has two ports linked to switch "B" (which is a CDP neighbor and also the STP root device) and STP blocks traffic on one port and forwards traffic on the other:

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