From: Pierre-Alex (paguanel@hotmail.com)
Date: Sun Jun 04 2006 - 10:17:59 ART
Hi Group,
Here are some lab results on oversubscription and the default-class verifying
Cisco Theory.
It was very useful to me in clarifying things.
1- RIP, OSPF and EIGRP update traffic will not be dropped even if 100% of
link is reserved to other classes and these classes use their allocations.
2- When saturating a link, there is 1K of traffic that cannot be used -
reseverved by the IOS .
3- BGP will not be able to function because of not having pak_priority set if
the link is saturated.
For details explainations you can read the summary below (from Cisco Doc).
"The RIP and OSPF (and EIGRP) routing processes running on a router's core CPU
mark all traffic they originate with both IP precedence 6 and pak_priority. In
contrast, the Border Gateway Protocol (BGP) instructs TCP to mark its traffic
with IP precedence 6, but does not set pak_priority.
RSP-based QoS and other platforms, including the Cisco 7200, 3600, 2600 series
places pak_priority traffic in a separate set of queues other than
class-default and marks such messages with a special weight value (currently
1024)."
http://www.cisco.com/en/US/tech/tk543/tk544/technologies_tech_note09186a00800
94612.shtml
Kind regards,
Pierre
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