[j-nsp] Inter provider LDP based L2VPN between a Juniper network and a Cisco network

[Alexandre Snarskii]

On Wed, Jul 28, 2010 at 11:10:12PM +0300, Amos Rosenboim wrote:
> Hello All,
> 
> I'm trying to configure an inter provider LDP based L2VPN between a  
> Juniper network and a Cisco network.
> The topology is roughly as follows:
> 
> Cisco PE-----Cisco P------Cisco P------Cisco ASBR------Juniper  
> ASBR-------Juniper P-------Juniper P-------Juniper PE.
> 
> In order to achieve this I need to establish the tunnel LSP between  
> the PEs in both networks and than establish the LDP signaled VC on top  
> of the tunnel LSP.
> To establish the tunnel LSP the two ASBRs exchange IPv4+label (or  
> labeled unicast in Junos language ) routes between them and advertise  
> to each other the loopback IP of the PEs.
> On the Cisco ASBR we simply redistribute the Juniper PE loopback into  
> the igp and thus the PE has both a route and a label to reach the  
> Juniper PE
> However on the Juniper side I cannot do the same.
> My question is what is the alternative method to achieve the same  
> result on the Juniper side?
> The solution I can think of is to use labeled unicast routes over iBGP  
> between the Juniper ASBR and the Juniper PE but I'm not sure it will  
> work (the Juniper network is not under my control so I cannot test).

At my past work we did inter-AS l2circuits exactly that way - eBGP with 
labeled-unicast between AS (one ASBR is Juniper, other is Cisco), 
then iBGP with labeled-unicast inside. 
Works fine. 

One of reasons of not to redistribute eBGP into OSPF is a lots of 
horror stories on what happens when you're entering 
router ospf NNNN 
 no redistrubute bgp route-map LOOPBACKS-TO-BE-REDISTRIBUTED
on Cisco routers. 

> If this is the solution than should the Juniper P routers also get  
> this route or would the Juniper PE impose two labels for the address  
> of the Cisco PE (the label derived from BGP for the Cisco PE + the  
> label to reach the Juniper ASBR)

IIRC, ingress PE will have to push three labels - internal label
to reach ASBR, then label to PE and then l2circuit label.