[c-nsp] BFD and no ip redirects ?

[Roger Wiklund]

On Tue, Dec 7, 2010 at 12:53 PM, selamat pagi <ketimun at gmail.com> wrote:
> According to Ciscos config guide, *no ip redirects* need to be configured
> for BFD
>
> I'm trying to understand why this is required.
>
> thanks, keti
> _______________________________________________


Before using BFD echo mode, you must disable the sending of Internet
Control Message Protocol (ICMP) redirect messages by entering the no
ip redirects command, in order to avoid high CPU utilization.

from ietf draft:

BFD Echo packets MUST be transmitted in UDP packets with destination
   UDP port 3785 in an IPv4 packet.  The setting of the UDP source port
   is outside the scope of this specification.  The destination address
   MUST be chosen in such a way as to cause the remote system to forward
   the packet back to the local system.  The source address MUST be
   chosen in such a way as to preclude the remote system from generating
   ICMP Redirect messages.  In particular, the source address SHOULD NOT
   be part of the subnet bound to the interface over which the BFD Echo
   packet is being transmitted, unless it is known by other means that
   the remote system will not send Redirects.