Should routers send redirects by default?

Ricky Beam jfbeam at
Sat Aug 21 01:24:43 UTC 2010

On Fri, 20 Aug 2010 20:43:39 -0400, Mark Smith  
<nanog at> wrote:
> You're assuming the cost of always hair pinning traffic on an interface
> is cheaper than issuing a redirect.

I am saying no such thing. (a single redirect packet is always more  
efficient.)  I *am* saying ICMP redirects are a mistake that should not be  
replicated in IPv6.  They are too easy to abuse, which is why they are  
almost universally ignored by IPv4 hosts.

In a *properly* configured network, redirects should not be necessary.  
(everything on the local LAN should know what's on the local LAN.) [For  
the record, my own networks don't follow that rule. :-) Coworkers throwing  
random crap on the wire doesn't help. *sigh* Don't go there.]

IPv6 has more than enough mistakes glued into it.  Redirects are a mess  
that does not need to be there.  For the purests who insist on making ugly  
networks that are trival to subvert, make ICMPv6 redirects *OPTIONAL*,  
*REQUIRING* explicit configuration to enable.  Without strong  
authentication/authorization mechanisms, it'll be the same mess that it is  
in IPv4.


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