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Forum Discussion

cwkim_261931's avatar
cwkim_261931
Icon for Nimbostratus rankNimbostratus
Jan 03, 2019

Is SRC MAC(last hop mac) changed in connections when other router send packet?

Hi,

 

I used auto last hop.

 

And I want to know that src mac(last hop mac) is changed when other router send packet instead of main router.

 

ex) router A MAC : AA router B MAC : BB BIG-IP MAC : CC

 

router A <-1-> BIG-IP <--> Server

 

(before) <-1-> src mac : AA dst mac : CC Create a connection(last hop mac : AA)

 

(after) <-1-> src mac : BB dst mac : CC Reuse a connection(Is last hop mac changed "BB"?!)

 

application delivery
BIG-IP
LTM

2 Replies

  • Dave_McCauley_3's avatar
    Dave_McCauley_3
    Icon for Cirrostratus rankCirrostratus
    Jan 04, 2019

    Hi cwkim,

     

    I'm not 100% sure about the example you've described, but I think you're trying to see what would happen if you have redundant upstream routers and one fails?

     

    Check out this KB article which describes how to configure this setup.

     

    https://support.f5.com/csp/article/K2211

     

    The short answer is if the router fails, it will continue to send traffic to the original router per the article.

     

    --D

     

  • Stanislas_Piro2's avatar
    Stanislas_Piro2
    Icon for Cumulonimbus rankCumulonimbus
    Jan 04, 2019

    The answer is NO

     

    Source MAC address doesn’t change in connection table. The connection will fail!

     

    If you want to support Mac failover, you have to create a gateway pool with both routers and add this pool as last hop pool in the virtual server!