Hi Iwase

As I mentioned, I sent an e-mail to someone about this error:

> [ashaikh@vsp-vpe-west ~]$ sudo ip route add vrf blue 172.16.0.1 encap 
> mpls  80 via 192.168.10.3 RTNETLINK answers: Network is unreachable

Here's his response:

"Looks like the MPLS code is not handling recursive lookups - which it should.

I'll work on patch when I get a few minutes; should be able to get to it by the 
end of this week"

So, I'd suggest let's wait till I get his patch and get to try it out in my 
test-bed. If it works, things will be considerably simpler.

aman

-----Original Message-----
From: Iwase Yusuke [mailto:iwase.yusu...@gmail.com] 
Sent: Tuesday, February 13, 2018 7:31 PM
To: SHAIKH, AMAN (AMAN) <asha...@research.att.com>
Cc: gobgp-devel@lists.sourceforge.net
Subject: Re: [GoBGP-devel] MPLS label issue with VPNv4 routes

Hi Aman,

I really appreciate!
I will also try them through sending message to FRR/Zebra.

Thanks,
Iwase


On 2018年02月14日 04:10, SHAIKH, AMAN  (AMAN) wrote:
> 
> Hi Iwase
> 
> I tried the following, but got an error:
> [ashaikh@vsp-vpe-west ~]$ sudo ip route add vrf blue 172.16.0.1 encap 
> mpls  80 via 192.168.10.3 RTNETLINK answers: Network is unreachable
> 
> I'm going to ask someone who knows more about how MPLS and VRFs work on Linux 
> to see if there is some other way to make this work.
> 
> aman
> 
> -----Original Message-----
> From: Iwase Yusuke [mailto:iwase.yusu...@gmail.com]
> Sent: Tuesday, February 13, 2018 12:54 AM
> To: SHAIKH, AMAN (AMAN) <asha...@research.att.com>
> Cc: gobgp-devel@lists.sourceforge.net
> Subject: Re: [GoBGP-devel] MPLS label issue with VPNv4 routes
> 
> Hi Aman,
> 
> Thank you for your confirmation!
> 
>   > --> This is definitely a possibility except you will have to consult 
> FRR/Zebra  > to determine 'dev ens8' part, right? In any case, I will try 
> this out in my  > testbed and let you know what happens.
> 
> Oops, I mistook. I want to remove 'dev ens8' part too, because GoBGP is not 
> maintaining the info (or list) of the interfaces. Ideally, I want to push 
> routes with only BGP's next-hop like;
>       $ ip route show vrf blue ...<snip>
>       172.16.0.1 encap mpls  80 via 192.168.10.3
>       192.168.1.0/24 encap mpls  80 via 192.168.10.3
> 
> If possible, I guess we can make the ZClient implementation keep (relatively) 
> simple.
> 
> Thanks,
> Iwase
> 
> 
> On 2018年02月13日 11:17, SHAIKH, AMAN  (AMAN) wrote:
>>
>> Hi Iwase
>>
>> Comments inline ...
>>
>>    > This is perhaps a complicated transaction with FRR/Zebra. GoBGP will 
>> have to  > do this transaction when it imports a VPNv4 route into a VRF. It 
>> will have to  > instruct FRR/Zebra with two things:
>>    > - Encapsulate the route with label associated with it.
>>    > - Resolve the BGP next-hop in the default forwarding table even though 
>> the  > route is installed in the blue VRF.
>>    >
>>    > Let me know what your thoughts are.
>>
>> Let me clear my head, first.
>> You mean the current GoBGP "additionally" need to install two route;
>>
>> 1. forwarding MPLS labeled traffic to VRF;
>>       $ ip -f mpls route show ...<snip>
>>       80 dev blue
>>
>> --> Without this route, MPLS labeled traffic coming from the backbone will 
>> be dropped by the PE. This route tells PE to pop VRF-label (80) from the 
>> packet and consult the forwarding table of blue VRF for the IP destination 
>> address stored in the IP portion of the packet.
>>
>> 2. pushing traffic from ECs to MPLS backbone;
>>       $ ip route show vrf blue ...<snip>
>>       172.16.0.1 encap mpls  19/80 via 10.202.0.8 dev ens8
>>       192.168.1.0/24 encap mpls  19/80 via 10.202.0.8 dev ens8
>>
>> For the "1." route, I guess we can install it when creating VRF, but not yet 
>> implemented.
>>
>> --> Yes, agree with you.
>>
>> For the "2." route, related to the latter point you mentioned, can we 
>> specify them like the following?
>>       $ ip route show vrf blue ...<snip>
>>       172.16.0.1 encap mpls  80 via 192.168.10.3  dev ens8
>>       192.168.1.0/24 encap mpls  80 via 192.168.10.3  dev ens8
>>
>> --> This is definitely a possibility except you will have to consult 
>> FRR/Zebra to determine 'dev ens8' part, right? In any case, I will try this 
>> out in my testbed and let you know what happens.
>>
>> In other words, I want to avoid resolving the outer label and MPLS's 
>> next-hop from the BGP's next-hop (if we can). I guess it helps the 
>> implementation simple.
>>
>> --> Yes, I understand.
>>
>> I took a (little) look at FRRouting implementation, bgpd does not seem to 
>> resolve the outer label and MPLS's next-hop from the BGP's next-hop, because 
>> it does not call "*_NEXTHOP_LOOKUP" messages.
>>
>> --> I'm not surprised FRR's bgpd does not handle this. It's fairly 
>> complicated given multi-step resolution of BGP next-hop along with multiple 
>> VRFs.
>>
>> aman
>> ---------------------------------------------------------------------
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