[c-nsp] MPLS VPN over mGRE

[David Prall]

I asked Craig Hill about the feature pointing him to your support forum post. He said there is no special signaling. The route map does all the work. 

David
--
I'm currently all thumbs so I apologize for the short message.

On Jan 31, 2013, at 3:07 AM, "John Neiberger" <jneiberger at gmail.com> wrote:

> I bet you're right. I should keep digging for some Cisco Live presentation or something. I was hoping someone from Cisco would respond and explain the magic fairy dust in this configuration. As you said, it must be that the inbound route-map  also causes the neighbors to use SAFI 64 in outbound updates. The docs I've seen so far don't say how it happens, they just said, "And in this step, magic happens" or something similar.  :)
> 
> John
> 
> 
> On Thu, Jan 31, 2013 at 1:02 AM, Adam Vitkovsky <adam.vitkovsky at swan.sk> wrote:
>> Aah I see, so it’s got to be the route-map than, mapping the particular neighbor with a profile –causing the neighbors to negotiate safi 64 support.
>> 
>> You could try issuing  “sh ip b vpnv4 a nei x.x.x.x” to see whether safi 64 has indeed been negotiated between the peers.
>> 
>>  
>> 
>> I bet the insides are explained in some cisco presentation.
>> 
>>  
>> 
>> adam
>> 
>>  
>> 
>> From: John Neiberger [mailto:jneiberger at gmail.com] 
>> Sent: Wednesday, January 30, 2013 6:16 PM
>> To: David Prall
>> Cc: Adam Vitkovsky; cisco-nsp at puck.nether.net
>> 
>> 
>> Subject: Re: [c-nsp] MPLS VPN over mGRE
>>  
>> 
>> That's exactly right. The part I can't figure out is what triggers the proper signalling. The BGP config for outbound vpnv4 updates looks like standard L3VPN. I'm trying to understand what causes it to send the tunnel information in the NLRI. I believe it is using SAFI 64. What causes it to use SAFI 64 instead of 128, which is what would normally be used for MPLS VPNs?
>> 
>>  
>> 
>> That's the part that's baking my noodle. I'm just not sure how it's working under the hood.
>> 
>>  
>> 
>> John
>> 
>>  
>> 
>> On Wed, Jan 30, 2013 at 9:15 AM, David Prall <dcp at dcptech.com> wrote:
>> 
>> Sounds like you are using BGP Signaled MPLS VPN over mGRE which uses a
>> Route-Map on the neighbor relationship to provide the tunnel information.
>> http://www.cisco.com/en/US/docs/ios-xml/ios/interface/configuration/xe-3s/ir
>> -mpls-vpnomgre-xe.html
>> 
>> David
>> 
>> --
>> http://dcp.dcptech.com
>> 
>> 
>> 
>> > -----Original Message-----
>> > From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-
>> > bounces at puck.nether.net] On Behalf Of John Neiberger
>> > Sent: Wednesday, January 30, 2013 10:55 AM
>> > To: Adam Vitkovsky
>> > Cc: cisco-nsp at puck.nether.net
>> > Subject: Re: [c-nsp] MPLS VPN over mGRE
>> >
>> 
>> > The type of MPLS VPN over mGRE that we're using doesn't use a
>> > preconfigured
>> > tunnel interface or NHRP. As I understand it, the peers share
>> > tunnel-related information in vpnv4 updates using a SAFI of 64. This tells
>> > the other peers that those prefixes are related to the mgre tunnel and
>> that
>> > signals the receiving router to set up an adjacency over the multipoint
>> > tunnel, but I'm not quite sure how it does this. I don't understand what
>> > element of the config tells the router to use SAFI 64 in the vpnv4 updates
>> > instead of just treating them like regular L3VPN vpnv4 updates. It's kind
>> > of confusing. There seems to be a lot of magic happening under the hood
>> > here that I'm missing.
>> >
>> > John
>> >
>> >
>> > On Wed, Jan 30, 2013 at 1:15 AM, Adam Vitkovsky
>> > <adam.vitkovsky at swan.sk>wrote:
>> >
>> > > Wow they really shrunk it down to three commands plus the route-map,
>> > now
>> > > that's something.
>> > >
>> > > > or is there some other mechanism that triggers tunnel endpoint
>> > discovery?
>> > > I believe since it's called mGRE it has to be NHRP taking care of
>> > > everything
>> > > in the background.
>> > > Does the loopback IP has to be allocated from a common range that has to
>> > be
>> > > shared among the PEs?
>> > >
>> > > I thought it's done via standard mGRE tunnels:
>> > >
>> > > interface Tunnel0
>> > > ip address 192.168.1.1 255.255.255.0
>> > > ip mtu 1440
>> > > ip nhrp authentication cisco123
>> > > ip nhrp map multicast dynamic
>> > > ip nhrp network-id 1
>> > > tunnel source FastEthernet0/0
>> > > tunnel mode gre multipoint
>> > > tunnel key 0
>> > > ip router isis 1
>> > >
>> > > -maybe "mpls ip" cmd. wouldn't work with mGRE Tunnel Int.
>> > >
>> > >
>> > > adam
>> > >
>> > >
>> 
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>