Cisco SD-WAN prefix list & data prefix list update

[RS19]

Wanted to understand the best practices when updating the prefix-list & data prefix list in SD-WAN network.

For example I have the below prefix-list

list_abc: 10.10.10.0/24
This prefix list has been used in Centralized policy.

I wanted to added new subnet to this prefix list: Say add 20.20.20.0/24 (list_abc: 10.10.10.0/24 & 20.20.20.0/24) 

What is the best practices to do it ? Just edit and add the new subnet to the prefix list or create a new prefix list and add the new prefix list and delete the old one.

What is the normal & best practice to achieve this ? No downtime

[MHM Cisco World]

For both cases there is downtime 

MHM

[RS19]

Can you please explain the reason why there will be down time ?

[MHM Cisco World]

push modify policy need edge to process and re-join OMP with TLOC, this why downtime can happened 

MHM

[Kanan Huseynli]

Could you please provide reference?

Normally, policy push does not require OMP re-establishment

[Kanan Huseynli · Accepted solution]

Hi,

option 1 works well without any down time. Add new subnet/mask to the prefix list (comma , separated) and that's all. Note that, whereever this prefix-list is referenced gets update as soon as you push configuration.

Create and delete would also work. Below is the workflow:

1) create new prefix-list
2) go to respective policy section/element where prefix-list is referenced, edit prefix-list (automatically vsmart update is required, push config)
3) go to next policy section/element where prefix-list is referenced,edit prefix-list (automatically vsmart update is required, push config)
4) delete old prefix-list

I dont see any reason to create new one, when you have prefix-list where you add easily do "add" operations. The idea to have grouping (via prefix-list) is you can add/ remove subset elements (subnets) easily.