[e2e] IP options
fred at cisco.com
Thu May 3 12:59:56 PDT 2001
At 08:51 PM 5/3/2001 +0200, Stefaan De Cnodder wrote:
>Does someone know whether IP options are used a lot today? Does there
>exist measurements showing the fraction of packets carying IP options in
options are not heavily used today. Note I did not say "not used", I said
"not heavily used".
Reason: much equipment that constitutes parts of the backbone today is
Cisco 7500, 7200, 7000, and lower equipment. This equipment kicks all
traffic having IP options out of its fast path and into the slowest
processing path in the system. This is also how packet fragmentation is
handled, and anything else more complicated than "pick a next hop, put the
appropriate link layer header on it, and pitch it out."
The Cisco GSR and (I understand) the Juniper M40 are a bit more
enlightened. They retain the capability of pitching things to the process
path, but they do attempt to handle known options that require
straightforward processing in the fast path.
If you plan to propose a new option that would require hardware or firmware
support, though, think in terms of product managers saying "show me the
business case" before starting a hardware spin.
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