Cisco ASA cluster control link MTU

[umeshunited]

What is the reason behind increasing MTU on CCL ( cluster control link)?

Is it because in the worst-case scenario where one of the boxes fails, CCL will be responsible for carrying heavy traffic ?

[nspasov]

Hi there. Traffic is going through the CCL when one cluster member needs to forward packets for sessions that belong to another member. The redirected traffic adds an additional trailer. As a result, this can cause fragmentation. Consequently, you want the MTU of the CCL to be at least 100 bytes higher than the one set of your data interfaces. All of this is very well described in the Cisco Live session:

https://www.ciscolive.com/global/on-demand-library.html?search=cluster&search.event=ciscoliveus2019#/session/1542224329797001rye8

I hope this helps!

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