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

Thu Aug 15 17:09:40 EDT 2013

Thanks folks, as usual, very helpful
 I went back to the way I tested this a
while back
 simply redis bgp learned bh routes into ospf, and then ospf is
already redis’d at a multihomed ce-pe location
. That’s it, now the 1,000+
routes show up in all the pe’s
 customer facing pe’s and internet facing
pe’s
 I watched the cpu on the me3600’s and one of the asr901’s and spiked
on asr901 during route learning but settled back down to about 10/20%.... so
I feel ok about this.

Thanks again

Aaron

From: Mattias Gyllenvarg [mailto:mattias at gyllenvarg.se] 
Sent: Thursday, August 15, 2013 3:28 PM
To: Aaron
Cc: Aaron; cisco-nsp; LavoJM
Subject: Re: [c-nsp] why are packets not following the more specific route -
xr 4.1.2 (asr9k)

Yeah, then its the next hop of the 0/0 thats relevant. 

How many routes do you have in ibgp then? Sounds like very few...

On Thu, Aug 15, 2013 at 10:25 PM, Aaron <aaron1 at gvtc.com> wrote:

Internet routes?  I have only one
. Yours truly 0/0  
.I learn one route via
ebgp from my upstream provider
 0/0

I learn 1,000+ other routes via ebgp (multiphop serveral hops away) from
another neighbor
.this is the blackhole appliance injecting bgp routes into
my same internet border asr9k
.all those bh routes have a next hop of a
private ip subnet that this same asr9k is directly connected to
so those
routes have next hop of the bh interface of the appliance
.

Aaron

From: Mattias Gyllenvarg [mailto:mattias at gyllenvarg.se] 
Sent: Thursday, August 15, 2013 3:02 PM

To: Aaron
Cc: Aaron; cisco-nsp; LavoJM
Subject: Re: [c-nsp] why are packets not following the more specific route -
xr 4.1.2 (asr9k)

The internet routes are the relevant ones. Do they point too lo0 or remote
end?

 Im sure one of the knights of the round table (Gert, Oliver, Adam etc)
could answer about L3 processing at the end point.

On Thu, Aug 15, 2013 at 9:35 PM, Aaron <aaron1 at gvtc.com> wrote:

The next hop of those bh routes is an ip address on the distant end of a
layer 2 segment which is connected to that border asr9k

Aaron

From: Mattias Gyllenvarg [mailto:mattias at gyllenvarg.se] 
Sent: Thursday, August 15, 2013 2:27 PM
To: Aaron
Cc: Aaron; cisco-nsp; LavoJM

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

I'm 100% on this but.

Are they destined for the remote end of the link they might not get
processed.

But if they are destined for the loopback of LER2 then they should.

On Thu, Aug 15, 2013 at 8:24 PM, Aaron <aaron1 at gvtc.com> wrote:

If ler1 flows everything via 0/0 lsp towards ler2, doesn't ler2 pop all mpls
tags prior to routing out towards internet via def rt ?..... if so couldn't
a more specific routing decision be made at that point towards blackhole /32
routes ?

Aaron

p.s. Why was vanilla ip forwarding more straightforward and easier than this
? J

From: Aaron [mailto:dudepron at gmail.com]
Sent: Thursday, August 15, 2013 1:16 PM
To: Aaron
Cc: LavoJM; cisco-nsp

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

No label to the blackhole?

If LER1 isn't getting the routes how is it going to build the LSP to the
blackhole?

On Thu, Aug 15, 2013 at 2:05 PM, Aaron <aaron1 at gvtc.com> wrote:

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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-- 
Med Vänliga Hälsningar
Mattias Gyllenvarg

-- 
Med Vänliga Hälsningar
Mattias Gyllenvarg

-- 
Med Vänliga Hälsningar
Mattias Gyllenvarg