Clarification required regarding Holdtime

[Pravin]

Hi Todd,

Please could you clafify the following:

When using the commands "Show CDP Neighbor" and "Show CDP Neighbor Details" does the Holdtime figure represent the amount of time my router will actually hold the CDP Packet from the neighbor device? or is this the amount of time that the neighbor device has requested my router to hold the CDP Packet.

eg
Device ID, Local Int, Holdtime ...............
R1, Serial 0/1, 157

The reason I'm asking is that when i've used the "Show CDP" command I get the following result:

Sending CDP Packet....60
Sending Holdtime...... 180


Many thanks,

Pravin.

[fayaz79]

helo friend !

The cdp timer value is for sending device it will use this value to send CDP packet to its neigboure .

the Cdp holdtime value is for the recieving device that when recieving device recieve packet it will hold it for the defined time in sender cdp packet.

but sender will send its cdp timer and holdtime value to its neighbour that he knows how often he will recive packets and how long he will hold that packets when he reciev one.

am i right guys .

fayaz

[Pravin]

Thanks for that Fayaz79.

I have another query and it concerns the "IP Name Server command"

on page 303 it states t(under The second command......) that "you can enter the IP addresses of upto to six servers" What does this actually mean?

Sorry if this sounds like a silly question but I just want to clearly understand what it means.

Does it mean that I can set up a DNS server and assign upto six IP addresses to this DNS server (therefore this DNS server is known by six IP addresses?

Cheers.

[lammle]

The ip name-server command allows you to configure the router to resolve hostname using up to six DNS servers.

Remember this is for administration of the network, not for packets traversing through the router. In other words, who wants to remember the IP address of the Dallas router when instead you can just type in "ping dallas" and have the name resolved for you.

Cheers!
Todd Lammle

[lammle]

Regarding the CDP post:

The CDP timers are set by default as follows:

Every Cisco device send CDP packets out every interface every 60 seconds.
Every Cisco device will help this information for up to 180 seconds before removing the device from the CDP table because no update packets have been received.

Cheers!
Todd Lammle

[Pravin]

Thanks for that Todd. It's clearer now.

Cheers,

Pravin.

[iworms]

You can think of holdtime as a request (or an expiration time stamp): the sending device asks the receiving devices to hold the information for xxx seconds. It is kind of like the time-to-live (TTL) value in DNS.