nanog mailing list archives

Re: BCP38 [Was: Re: TWC (AS11351) blocking all NTP?]


From: joel jaeggli <joelja () bogus com>
Date: Wed, 05 Feb 2014 13:43:13 -0800

On 2/5/14, 1:24 PM, Jay Ashworth wrote:
----- Original Message -----
From: "Octavio Alvarez" <alvarezp () alvarezp ods org>

Maybe I'm oversimplifying things but I'm really curious to know why
can't the nearest-to-end-user ACL-enabled router simply have an ACL to
only allows packets from end-users that has a valid source-address
from the network segment they provide service to.

The common answer, Octavio, at least *used to* be "our line cards aren't 
smart enough to implement strict-unicast-RPF, and our boxes don't have 
enough horsepower to handle every packet through the CPU".

As I've noted, I'm not sure I believe that's true of current generation
gear, and if it *is*, then it should cost manufacturers business.

There are boxes that haven't aged out of the network yet where that's an
issue, some are more datacenter-centric than others. force10 e1200 was
one platform that had this limitation for example.

Cheers,
-- jra



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