Upgradation of RR to MDT SAFI

How to upgrade the core router to MDT SAFI
To upgrade the core routers to mdt safi is one of the biggest challenge in service provider. Assuming SP is having two RR and every PE is having peering with them. A test bed is created with the given scenario given which is explicitly showing with some test cases and the outputs.

Basic Scenario
PE1, PE2, RR1 & RR2 are cisco 7200 with IOS 12.4 15T1

We have created a test vrf with default mdt for group End to end multicast tunnel established.

Figure 1

Test Bed 1
In test bed one we upgraded the ios of PE1 to cisco 12.2 (31)SB13 series which supports the mdt features. But the route reflectors are still using the non standard mdt features. But we did not faced any issue after up gradation and route reflectors are receiving the mdt values from PE1 with extended community 2:65500:1.

Test Bed 2
In the second test bed we upgraded the ios of RR1 from 12.4 15 T1 to 12.2 (31)SB 13 series. After the boot up process completed we checked the mdt bgp values but did not find anything. So under bgp address family ipv4 mdt we activated the neighbourship of PE1. After that we checked the same on RR1 but did not find anything. Corresponding on RR2 we are receiving the values with extended community 2:65500:1 from PE2 not from PE1. There after we activated the neighbourship of ipv4 mdt on PE1 towards RR1. As soon as it get activated on RR2 was able to receive mdt bgp routes with no extended community. But still on RR2 routes are coming from PE2 only not from PE1. Then we activated the neighbourship of ipv4 mdt for RR2. After that we received the updates from PE1 to RR2 with extended community 2:65500:1. But RR1 is not forwarding the mdt safi updates to PE2. PE2 is only receiving the updates with extended 2 community from RR2. For this we need to activate the mdt for PE2. As soon as it is activated, PE2 is able to receive the routes from the both RRs.

Results:- If the PE is using mdt safi and route reflectors are using mdt safi & pre mdt safi in this case on PE you need to activate the ipv4 mdt for both the route reflectors so that PE can send the updates to RR1 with mdt safi and for RR2 it sends the update with extended 2:65500:1 community. In short we can upgraded RR1 is backward compatabile to the PE with respect to the mdt. Only one thing which we need to take is that to enable mdt safi for the non mdt PE.

Test 3
In this test bed we upgraded the ios of PE2 to 12.2 (31) SB13. After the boot up process we checked the values of mdt bgp but did not find anything. Then we activated the ipv4 mdt neighbourship of RR2 which is running on 12.4. 15 T1 ios. As soon as it came up PE2 is able to receive the updates from RR2. Ther after neighbourship of RR1 was activated and PE2 is able to receive the routes from RR1 also. The routes received by PE2 are without standard extended 2 community.

Result:- 12.4 15 T1 code was providing the backward compatibility with both. But if the RR is upgraded with 12.2 (31) 13SB series then it can send and receive the updates only to mdt group members not to non mdt group members.

If we are going to upgrade the ios of one route reflector and second will be running on non mdt safi code. In this type of scenario core routers will be getting the mvpn routes only from the non mdt safi RR. You cannot provide the redundancy. So the best is that first upgrade the PE routers there after upgrade the route reflectors.


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