Portchannel mode "ON" EEM MAC detection

[Nikolay Kirtchev]

Hi guys,

Got a very weird scenario and would appreciate any help.

Got 2 3750 clusters - site A and site B.

They are connected via 2 lines bundled into portchannel each end.

Since the ISP providing both lines does not support LACP or PaGP those are static "mode on".

My problem is that there are ISP devices on both lines (between site A and siteB) and because of lack of dynamic protocols portchannel at site A is not able to detect line failure at site B and vice versa.

So what happens is (imagine port X, site A goes down):

Site A removes it from the portchannel and starts to transmit via the other working like.

However, the returning traffic uses the dead line to return replies - of course not in all cases, but enough to have malfunctioning network.

My question is, is it possible to configure some probing on MAC address towards remote interface and if that fails to bring down the port towards that  MAC.

I believe if this is done on both sides it might help me to bring down the failed line both ends.

That way only a single line will remain active and it should work via it.

Many thanks in advance!

Nikolay

[Joe Clarke]

EEM isn't magic in that it doesn't have deeper API access to the device.  In other words, if you can do what you want manually via the CLI or via SNMP, then EEM can automate it.  What kind of MAC probing would you like to do?  How would you do this manually?  My gut tells me that this won't work as there is not an L2 way to do the probing you want (from the CLI).

[Nikolay Kirtchev]

Hi Joe,

Thank you very much for your reply.

Looking further I have found that CDP is supported as protocol on both lines.

So decided to use it to achieve my goal i.e. when CDP neighbor is removed from the CDP table to shut down the interface from which the CDP advertisement for it came in.

I have configured:

event manager applet cdp-send-syslog-7
event neighbor-discovery interface gi1/0/7 cdp delete
action 1.0 syslog msg "CDP state change - 7!"

event manager applet Shut-Down-gi1/0/7
event syslog pattern "%HA_EM-6-LOG: cdp-send-syslog-7: CDP state change - 7!"
action 1.0 cli command "enable"
action 1.1 cli command "configure term"
action 1.2 cli command "interface gi1/0/7"
action 1.3 cli command "shut" 

Unfrtunately - only the first applet works. Maybe I am missing something.

If you could advise on this it will be awesome!

Many thanks.

Nikolay

[Joe Clarke · Accepted solution]

Not sure why you want two applets.  You don't need them, and what you're doing here won't work anyway.  EEM cannot intercept a syslog message it generates.

Just do:

event manager applet cdp-send-syslog-7
event neighbor-discovery interface gi1/0/7 cdp delete

action 1.0 cli command "enable"
action 1.1 cli command "configure term"
action 1.2 cli command "interface gi1/0/7"
action 1.3 cli command "shut" 

[Nikolay Kirtchev]

You are a star!

Thank you Joe!

Nikolay