[c-nsp] MPLS VPN over mGRE

[Joe Cozzupoli]

Guys, check out the following session on Cisco Live 365:

BRKRST-2045 (San Diego 2012 and/or London 2013)

Sent from my iPad

On 31/01/2013, at 19:06, 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<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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>> 
>> ** **
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