[j-nsp] Krt queue issues

Naslund, Steve SNaslund at medline.com
Wed Oct 3 21:50:03 UTC 2012


I think route retention might help in the event the table was cleared or
routing process restarted but I don't that it will help with a boot
because the table structures are being built as part of the system
initialization.  In reality, I would expect the static routes to get
installed very early as soon as the routing process comes up.  Since you
will need a route to your BGP neighbor (even though it may be directly
connected, it is still a route), routing has to be up BEFORE BGP
establishes and by definition your static routes will have to be up
before your BGP routes are ready.  How well your router responds to
traffic during an initial boot and during a 300,000 route update is
another story.  My experience with very large routers and tables is that
you will have a hard time guaranteeing user traffic will pass with very
much performance during an event like a full table rebuild.  Luckily
with the bandwidth we have these days and the CPU power on the routers,
it does not take that long to pull in a full internet table and begin
handling traffic.

Steven Naslund

-----Original Message-----
From: Jensen Tyler [mailto:JTyler at fiberutilities.com] 
Sent: Wednesday, October 03, 2012 9:45 AM
To: nanog at nanog.org
Subject: RE: [j-nsp] Krt queue issues

Look into Static route retain. Should keep the route in the forwarding
table.

>From Jniper site
<<<
Route Retention

By default, static routes are not retained in the forwarding table when
the routing process shuts down. When the routing process starts up
again, any routes configured as static routes must be added to the
forwarding table again. To avoid this latency, routes can be flagged as
retain, so that they are kept in the forwarding table even after the
routing process shuts down. Retention ensures that the routes are always
in the forwarding table, even immediately after a system reboot.
>>>

Thanks,

Jensen Tyler
Sr Engineering Manager
Fiberutilities Group, LLC


-----Original Message-----
From: juniper-nsp-bounces at puck.nether.net
[mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of Benny Amorsen
Sent: Wednesday, October 03, 2012 8:32 AM
To: Jared Mauch
Cc: Saku Ytti; juniper-nsp at puck.nether.net
Subject: Re: [j-nsp] Krt queue issues

Jared Mauch <jared at puck.nether.net> writes:

> As far as the fallback 'default' route, if you are purchasing transit 
> from someone, you could consider a last-resort default pointed at 
> them. You can exclude routes like 10/8 etc by routing these to discard
> + install on your devices.

That only helps if the default gets installed first, though. If the
default has to wait at boot in the krt-queue behind the 300k+
Internet-routes, I have not really gained anything...

I suppose it is likely that a static default would be installed before
the BGP sessions even come up.


/Benny
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