From: Scott Morris (swm@emanon.com)
Date: Tue Feb 22 2005 - 14:11:49 GMT-3
Not so much as rewriting them (though some do) but more of ignoring the
implications.
The problem is that QoS is end-to-end, and what motivation does any ISP have
to treat your traffic better than one of their other customers?
They'll be happy to sell you SLAs though. And then will tell you how to
mark it.
Beyond that though, we have problems in perception. What is important to
your network may not be to mine. What makes a "prec 3" level of importance
to you may not have any correlation in my world.
This is where the Per Hop Bevior RFC's came in to try to give a common set
of interpretations at any network along the way. The Assured Forwarding
(AF) classes and Expedited Forwarding (EF) class came from there.
But it still boils town to money and motivation!
HTH,
Scott Morris, MCSE, CCDP, CCIE4 (R&S/ISP-Dial/Security/Service Provider)
#4713, JNCIP, CCNA-WAN Switching, CCSP, Cable Communications Specialist, IP
Telephony Support Specialist, IP Telephony Design Specialist, CISSP
CCSI #21903
swm@emanon.com
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Roy
Dempsey
Sent: Tuesday, February 22, 2005 11:56 AM
To: Cisco certification
Subject: Setting IP precedence in the real world?
Hi all,
I've always struggled with understanding and applying the correct QoS
solution to a particular problem. I'm working hard at understanding when and
where different solutions are appropriate. As with other topics, I think I
understand the theory, but need to understand the real-world application
properly.
While working through MQC, I couldn't help wondering about how important ip
precedence values are in the real world and, in particular, the Internet. On
private networks, I can see the value in setting the ip precedence value,
and providing levels of service using these values.
When sending traffic onto the Internet, is there any value in setting
precedence values? Would ISPs rewrite these values as standard? Even if ISPs
don't explicitly use precedence values, wouldn't it be beneficial where QoS
devices like WRED and WFQ are employed, as these can use the precedence
value?
Thanks again,
Roy
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