sh run out put explanation

Answered Question
Dec 31st, 2008

What do the following from output of sh run refer to?

no service pad

service tcp-keepalives-in

service tcp-keepalives-out

I have this problem too.
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Correct Answer by Collin Clark about 7 years 11 months ago

Yes if you're not using X.25, disable PAD.

service tcp-keepalives-in is to the router management plane, not traffic going through the router. Here's a common example; You telnet into a router and do some work. Instead of logging off the router you just close your terminal application. The router thinks your still connected and is waiting for input. If you do that enough times, you'll use up all your VTY lines and you won't be able to access the router via telnet. With service tcp-keepalives-in the router will timeout the session after inactivity ensuring you always have a VTY line available.

Hope that helps

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Collin Clark Wed, 12/31/2008 - 09:50

no service PAD shuts off PAD.

A packet assembler/disassembler, abbreviated PAD is a communications device which provides multiple asynchronous terminal connectivity to an X.25 (packet-switching) network or host computer. It collects data from a group of terminals and places the data into X.25 packets (assembly). A PAD also does the reverse, it takes data packets from packet-switching network or host computer and returns them into a character stream that can be sent to the terminals (disassembly).

service tcp-keepalives-in

To generate keepalive packets on idle incoming network connections (initiated by the remote host), use the service tcp-keepalives-in command in global configuration mode.

service tcp-keepalives-out

To generate keepalive packets on idle outgoing network connections (initiated by a user), use the service tcp-keepalives-out command in global configuration mode.

Hope that helps.

saidfrh Wed, 12/31/2008 - 09:55

So, if we are not using X.25, the above service should be disabled.

service tcp-keepalives-in, does this refer to keeping the TCP session open, while reciving syn, ack...TCP protocol activities?

Correct Answer
Collin Clark Wed, 12/31/2008 - 10:08

Yes if you're not using X.25, disable PAD.

service tcp-keepalives-in is to the router management plane, not traffic going through the router. Here's a common example; You telnet into a router and do some work. Instead of logging off the router you just close your terminal application. The router thinks your still connected and is waiting for input. If you do that enough times, you'll use up all your VTY lines and you won't be able to access the router via telnet. With service tcp-keepalives-in the router will timeout the session after inactivity ensuring you always have a VTY line available.

Hope that helps

saidfrh Wed, 12/31/2008 - 10:26

On another note, what does no ip source-route refer to?

Collin Clark Wed, 12/31/2008 - 10:30

IP source routing allows the sender of an IP packet to control the route that packet will take to reach the destination endpoint. By default, IP source routing is disabled on the routers and should only be enabled if your network needs call for it.

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