[c-nsp] Hierarchical FIB on Cisco 7600

[Pete Lumbis]

Hierarchical FIB is not enabled by default on 7600 and you must enable "cef
table output-chain build favor convergence-speed" like you mention.

Turning it on should have no impact. Turning it off could see a route
reprogram event and could cause packet loss while it happens. As with
everything, use caution.

The difference in commands is mainly in relation to software/memory. This
has the biggest impact on software based platforms like the 7200 but you'll
see an uptick in RP/SP memory usage by enabling, but only changes how
routes are built in hardware.


On Fri, Apr 25, 2014 at 3:30 AM, redscorpion69 <redscorpion69 at gmail.com>wrote:

> Hello,
>
> Does 7600 runs Hierachical FIB by default?
>
> The command to enable this should be:
>
> *cef table output-chain build favor convergence-**speed*
>
> The default on 7600 seems to be:
>
>
>
> *cef table output-chain build favor default*
> The document says:
>
> "General Characteristics
>
> Use the *cef table output-chain build favor* command to override the Cisco
> Express Forwarding table default operational behavior used to build output
> chains for forwarding of network traffic.
>  The default behavior for output chain building favors convergence, if this
> behavior is permitted by the platform."
>
> So, does this mean that I can leave default for BGP PIC, and if not, what
> would be that impact of changing from *default *to *convergence-speed*?
> Could it be done during production?
>
> Regards
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