[c-nsp] why disable ip cache and direct broadcast in switch

Gert Doering gert at greenie.muc.de
Thu Feb 26 02:55:57 EST 2009


Hi,

On Thu, Feb 26, 2009 at 02:45:01AM -0500, Steve Bertrand wrote:
> For my own understanding, is it fair to assume:
> 
> - "no ip route-cache" forces punting to the RP for proc-switch
> - lack of "no ip route-cache" and without "ip cef" enabled (at all)
> implies 'proc-switch once, then fast-switch'
> - nothing explicitly set on an interface, but "ip cef" enabled globally
> will always use the compiled FIB
> 
> ...do I have this right?

I think it should be that way for recent-enough IOS images.

Older versions required an explicit "ip route-cache cef" in the interface
config.  (And there were more options, like "ip route-cache optimal" or
"ip route-cache same-interface", etc. etc. which contribute to the
confusion).

Cisco is slowly moving into the right direction: drop all switching paths
except CEF and process.  Simplify the code, get rid of corner cases and
bugs.

(Maybe also rewrite all the interface counter stuff at the same time...)

gert

-- 
USENET is *not* the non-clickable part of WWW!
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Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de
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