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New Member

no ip redirects is used for what

Please explain what for we use no ip redirects.

2 REPLIES
New Member

no ip redirects is used for what

Sunil,

In routers, 'no ip redirects' keeps the router from sending ICMP redirect messages to clients.

Redirects are used by a router when it knows that a better path exists for a client other than itself. A router will send a ICMP Redirect to the client pointing it to a different next-hop for a given destination in hopes the client will take this new path to this destination.

Redirects can be disabled for security reasons. It's possible a rogue router could enter the network with "better" paths but malicious intent. Therefore, we would want to avoid giving hosts a reason to change their path to the new, malicious router.

Here's a Cisco doc on when / why redirects are used:

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094702.shtml

Hope this helps!
Joey

Cisco Employee

no ip redirects is used for what

Just to expand a little futher on this.  Many time end device won't change their behavior when recieving an ICMP redirect, in this case the router just keeps sending redirects over and over.  Doing this causes more work for the CPU as we have to craft the ICMP redirect packet.  Due to this, many times its just easier to allow the host to continue sending the packets to the current router.

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