[j-nsp] /32 host routes on down interfaces

[Jake Khuon]

On Thu, 2010-04-22 at 14:03 -0500, Richard A Steenbergen wrote:

> inet.0: 326321 destinations, 3502101 routes (319320 active, 11 holddown, 316892 hidden)
> Restart Complete
> + = Active Route, - = Last Active, * = Both
> 
> 1.1.1.1/32         *[Local/0] 00:00:05
>                       Reject
> 
> And if you try to route traffic through the box for 1.1.1.1, it is
> rejected. The same is true even if you admin down the interface with
> "interface xe-0/0/0 disable", it always installs the /32 local route.
> 
> This seems like a bad thing to me. If the interface is down (either link
> or admin) I don't see why you'd need the local route installed in the
> routing table?

I don't work for nor have I ever worked for Juniper so I can't say for
certain but the likely explanation for this is that it is a holdover
from the gated origins of JunOS.  I do know the gated code (former gated
developer and architect) and in gated, IP interfaces are represented
internally by their logical interface address.  If the interface exists,
a host-interface entry is generated in the prefix tree and this will
show up in the RIB.


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