iamjeffvader's studymotron and rantatorium

Ok so it has been a while. I have done some testing on LDP based mVPN at this stage, not a huge amount, mainly basic functionality.

The first thing to note is 7750 MUST run in chassis mode D to allow the multicast commands required for mLDP. This means no IOM1 or IOM2 cards are allowed in the chassis and because of this I have a limited topology to play with.

Both PE routers are SR12s running CPM2-400G and have IMMs or IOM3 in the CE facing slots.  The CE routers are Cisco 1841, r4-ce1-rp is the RP and also the receiver, it’s config is below.  r5-ce2-src simply runs PIM on its uplink to pe2 and will source traffic to group 224.1.1.1.

Roll on up the 7750s.  The first task we do is create the VPRN service and place the CE facing interface in to the VRFs PIM process.  I have configured the CE facing interface name as “mvpn” just for clarity, it has no bearing on the mVPN configuration.  The remainder of the config is exactly the same as standard VPRN.  PIM configuration is very straightforward, all I do is enter the PIM process and add the interface.  The rest of the config below is defaulted.  I won’t be setting the RP address as I think that’s intrusive on the customers experience, they should have the freedom to change their RP as they see fit.

Once we do this, and assuming connectivity is good, we should see a PIM adjacency going up:

So that is the very basic element complete.  Now we just need to do the entire core!  Well not so much.  Per the diagram above I already have MP-BGP configured and both routers have address family mvpn-ipv4 activated.  I also have VPNv4 activated, not much point having mVPN and no IPv4 VPN to use.  Would anyone buy that service?

There is one other ‘core’  element we need to verify before we get in to the VRF specific multicast configuration.  We need to ensure our network interface will support multicast and the creation of mLDP trees. We simply enable it under the LDP interface…

and if we want to prevent multicast over an interface…

I have links to routers that do not run in mode D so multicast processing should be disabled.

OK so with MP-BGP and LDP multicast enabled we can configure the VPRN to carry the customers traffic.  That will come in the next post which will see the VPRN config and debug behaviour when the services comes up and how BGP updates trigger switchover to the S-PMSI.