[c-nsp] why are packets not following the more specific route - xr 4.1.2 (asr9k)

Aaron aaron1 at gvtc.com
Thu Aug 15 14:05:55 EDT 2013


Yes mpls core.

Traceroute on pc----- LER1---- mpls core-----LER2----- internet
						|
						Blackhole

Yes LER1 doesn't not have those /32 blackhole routes.... it does have the
def rt towards internet via LER2.

Aaron


-----Original Message-----
From: LavoJM [mailto:lavojm at secureobscure.com] 
Sent: Thursday, August 15, 2013 12:41 PM
To: 'Aaron'
Subject: RE: [c-nsp] why are packets not following the more specific route -
xr 4.1.2 (asr9k)

Are you running MPLS in the core, and the first LER does not have a FEC for
the /32, but it does have one for default/other-internet routes?

3


-----Original Message-----
From: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of
Aaron
Sent: Thursday, August 15, 2013 11:57 AM
To: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] why are packets not following the more specific route -
xr 4.1.2 (asr9k)

(x.x.x.x is one of the /32 blackhole routes)

Oh and when I do this on that boundary 9k "traceroute x.x.x.x vrf xyz source
y.y.y.y" it appears to NOT follow the default route out to the internet and
it seems that it does follow the more specific blackhole route.  why would
mpls l3vpn located computers deeper into my internal network NOT follow this
more specific route as the packets flow across the forwarding plane of this
boundary 9k ??

Aaron

-----Original Message-----
From: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of
Aaron
Sent: Thursday, August 15, 2013 11:49 AM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] why are packets not following the more specific route - xr
4.1.2 (asr9k)

I have a blackhole security device injecting routes into my internet
boundary asr9k.. I see that the bgp prefixes are rcv'd on my 9k and the are
installed in the per-vrf rib.  The next hop for those routes are via a
directly connected interface towards the blackhole.. But for some reason I
continue to see on traceroutes from a computer that's deeper into my
internal network via mpls l3vpn, that this computer's traceroutes flow right
passed that 9k's more specific routes and follows the default route out to
the internet.  Any idea why ?

 

Aaron

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