I don't want to talk around the bush for long. I disagree with a friend how a router would behave in a special configuration. Unfortunately I can't test it here to check my point of view. Specifically, the router should not perform ICMP redirects.

I'm of the opinion that the router would still route on the same interface if its routing table requires it to, even if ICMP redirects are disabled. My friend is of the opinion that the router with disabled ICMP redirects would not route on the same interface.

Does anyone know how the router would behave? Is there a RFC? Is this different from router to router? I am grateful for any assistance.

closed as off-topic by joeqwerty, Ward May 12 at 1:50

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  • 1
    Don't have an answer for you, but in the future you should give folks a longer time (~24 hours) to answer. @Anton answered you pretty much immediately and you accepted it two hours later. Perhaps it would be beneficial to allow folks on the other side of the world a chance to provide input. As it stands, it looks like you immediately accepted the answer that supported your position. – Havegooda May 10 at 15:18
  • The feature is rarelly used without the admin knowing it, as such you will know the impact if disabled, as each route are added by someone. please read that doc for explanation; cisco.com/c/en/us/support/docs/ip/… – yagmoth555 May 12 at 3:27

There aren't any limitations of routing traffic back through same interface. Disabling/enabling sending of ICMP redirects doesn't change principles of routing itself. Just if the ICMP redirects sending is enabled, the additional ICMP messages are sent to optimize the routing path, but the original packets are routed anyway.

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