This article explains why the dynamic routing protocol will re-negotiate after RG0 failover.

When an SRX cluster is running a dynamic routing protocol, for example OSPF or BGP and if RG0 fails over, the new primary RG0 needs to re-negotiate with the peer device.

This is expected behavior.

Nonstop Active Routing (NSR) can preserve interface and kernel information, saving the routing protocol information by running the routing protocol process (RPD) on the backup Routing Engine.

Many Junos OS platforms support NSR such as M/T/MX/EX (VC). However, most SRX platforms do not support NSR yet. 

So on the secondary node, there is no existing RPD daemon. Therefore, after RG0 failover happens, the new RG0 primary will have a new RPD and will need to re-negotiate with the peer device.

//RG0 as Primary in Node0 and Secondary in Node1

{primary:node0}
root@jtac-srx1500> show chassis cluster status

Cluster ID: 1
Node   Priority Status               Preempt Manual   Monitor-failures

Redundancy group: 0 , Failover count: 1
node0  200      primary                no      no       None
node1  100      secondary              no      no       None

Redundancy group: 1 , Failover count: 1
node0  200      primary                no      no       None
node1  100      secondary              no      no       None

//RPD running on primary Node(Node0) but not Secondary Node(Node1)

root@jtac-srx1500> show system processes extensive node 0 | grep rpd
 7989 root        1   4    0 87264K 21892K kqread   0:28  0.00% rpd
 
root@jtac-srx1500> show system processes extensive node 1 | grep rpd

2022-02-16: Removed "only SRX5000 platforms with version 17.4R2 or higher can support NSR" because SRX platform does not support NSR