EDGE MIGRATION : cEdge to another cEdge

[chess6016]

Good day , 

so I have client that has CISCO SD WAN solution , at his HQ he has 2 cEdges ISR  that are fully working on the fabric , he wants to swap them with 8000 series routers while keeping the connectivity of the HQ as much available as possible.

enrolling and onboarding process of the new Edges are quite clear an straight forward. what troubles me is that how to proceed with migration . 
please provide me with the best roadmap to achieve this, this is so important for me. 

thanks ! 

[balaji.bandi]

Good Option is 1 at time cut over, so you still have connectivity with others.

you mentioned HQ, how many branches you have how many routers they have , how they connected to HQ - using 2 Links ?

[chess6016]

 how they connected to HQ - using 2 Links ? > 3 links , hub and spoke and almost 100 branch

[balaji.bandi]

i mean  each branch have how many Physical Links to HQ ? Dual or single ?

[chess6016]

I am not sure about the branches since they count more than 100 , but I am sure that some have 2 exits and some have 1 exit. 
can you relate to why this is important sir ? 

thank you ! 

[balaji.bandi]

if you dual connection you can upgrade one at a time and test it, so you have easy roleback if not working to other link which is still old cedge router,

if only 1 link then you need to use one of test site and migrate to Cat 8K routers and learn lesson and upgrade rest.

[Kanan Huseynli]

Hi,

what type of routing is done on service side of hub routers? Static, dynamic, VRRP (or even HSRP with CLI-template)? Do you have centralized control policy which modifies overlay routing? Do both existing routers act as active/active (ECMP) or active/passive?

You may force router1 to be primary for ingress and egress traffic for Hub, then remove router2 and add new router with exact parameters for routing (still router1 will be primary transit device). Then you force router2 (which is new) to be new primary ingress&egress point for the site. And now you replace router1.

After you should make both act as it was before (before the change).

You will need to play service-side routing and OMP routing in order to do smooth migration.

[chess6016]

Hello, 

kind of late response , I am sorry. 
what do you want to point at by : Do you have centralized control policy which modifies overlay routing? > how will it affect the migration ?