Re: interface metric & quagga

From: "Bruce M. Simpson" <bms@xxxxxxxxxxx>
Date: Fri, 26 Jan 2007 18:38:53 +0000

Eugene Grosbein wrote:

RTM_NEWADDR contains 'metric 0' regardless of interface metric
value set with ifconfig before. quagga, since version 0.99.3,
takes metric value from RTM_NEWADDR message and this value overrides
right interface metric learned by quagga a milisecond before.
Then it passes zero interface metric to ripd that uses interface
metric as hop count increment for RIP-learned routes.
This effectively breaks RIPv2 for FreeBSD (quagga-0.99.2 and older
versions do not use metric from RTM_NEWADDR and work), perhaps RIPv1 too.

It's a mixed issue.

FreeBSD does not use the interface metric, so routing daemons shouldn't use that field.

However, many routing implementations use a metric or distance of 0 to indicate a directly-connected route or interface route, so it has special meaning.

We could deal with this situation better by explicitly setting the metric to an invalid value.
If/when we implemented equal-cost multipath, or source address selection policies, then we should use this field.

Verified with RELENG_4 and RELENG_6.
Is it kernel bug or quagga bug?

I also suggest to include next patch to the Ports tree
if no objections. It restores RIP support.

I'd rewrite the patch to wrap the assignment in #ifndef __FreeBSD__ so that it can be taken upstream more easily. If/when we do equal-cost multipath or source policy we can bump __FreeBSD_version.

Regards,
BMS
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