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What does 'link up' mean in 'show logging' output

Hi,

I have a 3750-X that is configured to log to a syslog server.  When I issue the 'show logging' command, the output tells me that the link is 'up' as shown below

Logging to 172.20.1.1  (udp port 514,  audit disabled,

    authentication disabled, encryption disabled, link up),

    28 message lines logged, 

    0 message lines rate-limited, 

    0 message lines dropped-by-MD, 

    xml disabled, sequence number disabled

    filtering disabled

Does this mean that the switch knows the syslog messages it is sending out are reaching the destination syslog server because it gets an acknowledgement from the destination?

TIA,

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Hall of Fame Super Gold

What does 'link up' mean in 'show logging' output

Bob

No the switch does not know for sure that the syslog server is up. And there are no acknowledgements if your router is using the normal transmission using UDP on port 514 (which your output says is the case). What the message means is that the switch has a route to the address of the syslog server and that it believes that the link toward the next hop is up.

HTH

Rick

3 REPLIES
Hall of Fame Super Gold

What does 'link up' mean in 'show logging' output

Bob

No the switch does not know for sure that the syslog server is up. And there are no acknowledgements if your router is using the normal transmission using UDP on port 514 (which your output says is the case). What the message means is that the switch has a route to the address of the syslog server and that it believes that the link toward the next hop is up.

HTH

Rick

New Member

What does 'link up' mean in 'show logging' output

Hi Richard, thanks for answering my question.

Hall of Fame Super Gold

What does 'link up' mean in 'show logging' output

Bob

Glad that I could help. Thank you for using the rating system to mark this question as answered. I hope to see more posts from you in the forum.

HTH

Rick

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