[94876] in North American Network Operators' Group
Re: Do routers prioritize control traffic?
daemon@ATHENA.MIT.EDU (Patrick W. Gilmore)
Mon Feb 12 09:51:02 2007
In-Reply-To: <20070212135558.GA28599@mozart.cs.colostate.edu>
Cc: "Patrick W. Gilmore" <patrick@ianai.net>
From: "Patrick W. Gilmore" <patrick@ianai.net>
Date: Mon, 12 Feb 2007 09:22:52 -0500
To: The NANOG mailing list <nanog@merit.edu>
Errors-To: owner-nanog@merit.edu
On Feb 12, 2007, at 8:55 AM, Christos Papadopoulos wrote:
> I know routers today have the ability to prioritize
> traffic, but last I heard, these controls are not
> often used for user traffic (let's not discuss
> net neutrality here).
>
> Are they used for control (e.g., routing) traffic?
>
> Please say a bit more than "It depends!" :-)
> Our students are interested in real-world practices.
Real world answer: It depends. :)
For instance, Juniper routers auto-police all traffic destined for
the main CPU.
Cisco routers (usually) do not. You can configure it, though. Newer
ciscos have very nice policing options for traffic to the main CPU.
Older ones still have options, but the policing can hurt the router
in its own way. There is also some auto-policing in ciscos, e.g.
only one ICMP echo request per second per source IP address will be
allowed to hit the CPU.
Hope that helps.
--
TTFN,
patrick
