IPv4 Router Alert Option

Fri May 23 19:30:11 UTC 2008

On Fri, 23 May 2008 15:00:02 EDT, Ron Bonica said:
> Folks,
> 
> It is my belief that many ISPs, will not accept datagrams containing the
> Router Alert IP option from customers. Do I have that right?
> 
> I am asking so that I might better evaluate Internet drafts that would
> require ISPs to accept such packets.

What you're likely to find in *reality* is that ISPs will be more than happy
to pass the packets along, but the corporate/consumer firewalls in place
at the ISP's *customers* will stomp on the options (see all the ways that
mismanaged firewalls fail to do ingress/egress filtering of rfc1918 packets,
or think "ICMP Frag Needed" means "This ICMP needs to be fragged", or...).

And it doesn't really matter if it's the ISP or the end site that screws it
up - if it gets thrown away, it gets thrown away.

Unless you had an ISP-specific use for Router Alert, where end-customer
behavior doesn't matter?

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