Tested on azure ovn-ic 

pre-merge testing

Always

1. Label one node as egress node
2. Create one egressIP object
% oc get egressip
NAME         EGRESSIPS     ASSIGNED NODE                               ASSIGNED EGRESSIPS
egressip-1   10.0.128.26   huirwang-0714a-rzsv5-worker-eastus1-2tnxk   10.0.128.26

3. Create a namespace test and 5 pods in it. label test name=qe to match egressIP object
4. Check ovn db on egress node
 % oc rsh -n openshift-ovn-kubernetes ovnkube-node-vr97d 
Defaulted container "ovn-controller" out of: ovn-controller, ovn-acl-logging, kube-rbac-proxy-node, kube-rbac-proxy-ovn-metrics, northd, nbdb, sbdb, kube-rbac-proxy-ncm, ovnkube-controller, ovnkube-node, drop-icmp
sh-5.1# ovn-nbctl --format=csv --no-heading find nat external_ids:name=egressip-1
3d8c1111-4118-4977-a666-85f60b9cc8c4,[],[],{name=egressip-1},"""10.0.128.26""",[],"""""",[],"""10.130.2.16""",k8s-huirwang-0714a-rzsv5-worker-eastus1-2tnxk,"{stateless=""false""}",snat
c2222c22-13ac-4de1-b532-8fd6805f2f9b,[],[],{name=egressip-1},"""10.0.128.26""",[],"""""",[],"""10.130.2.11""",k8s-huirwang-0714a-rzsv5-worker-eastus1-2tnxk,"{stateless=""false""}",snat
b8cd4165-f026-408e-8308-1758e0a97659,[],[],{name=egressip-1},"""10.0.128.26""",[],"""""",[],"""10.130.2.17""",k8s-huirwang-0714a-rzsv5-worker-eastus1-2tnxk,"{stateless=""false""}",snat
15fc7e89-3fcb-4418-b705-18a70614192d,[],[],{name=egressip-1},"""10.0.128.26""",[],"""""",[],"""10.130.2.15""",k8s-huirwang-0714a-rzsv5-worker-eastus1-2tnxk,"{stateless=""false""}",snat
3647833a-ee39-4df4-ba59-649f788d1ad5,[],[],{name=egressip-1},"""10.0.128.26""",[],"""""",[],"""10.130.2.13""",k8s-huirwang-0714a-rzsv5-worker-eastus1-2tnxk,"{stateless=""false""}",snat

4. Reboot egress node  huirwang-0714a-rzsv5-worker-eastus1-2tnxk  
5. Wait for egress node to be ready again.
% oc get nodes
NAME                                        STATUS   ROLES                  AGE     VERSION
huirwang-0714a-rzsv5-master-0               Ready    control-plane,master   5h1m    v1.27.3+0abcd84
huirwang-0714a-rzsv5-master-1               Ready    control-plane,master   5h1m    v1.27.3+0abcd84
huirwang-0714a-rzsv5-master-2               Ready    control-plane,master   5h1m    v1.27.3+0abcd84
huirwang-0714a-rzsv5-worker-eastus1-2tnxk   Ready    worker                 4h46m   v1.27.3+0abcd84
huirwang-0714a-rzsv5-worker-eastus2-zf6rn   Ready    worker                 4h46m   v1.27.3+0abcd84
huirwang-0714a-rzsv5-worker-eastus3-9mvsw   Ready    worker                 4h46m   v1.27.3+0abcd84

1. Check ovn db on egress node again, no above snat rules.
%  oc rsh -n openshift-ovn-kubernetes ovnkube-node-vr97d
Defaulted container "ovn-controller" out of: ovn-controller, ovn-acl-logging, kube-rbac-proxy-node, kube-rbac-proxy-ovn-metrics, northd, nbdb, sbdb, kube-rbac-proxy-ncm, ovnkube-controller, ovnkube-node, drop-icmp
sh-5.1# ovn-nbctl --format=csv --no-heading find nat external_ids:name=egressip-1
sh-5.1# 
2. % oc get egressip
NAME         EGRESSIPS     ASSIGNED NODE   ASSIGNED EGRESSIPS
egressip-1   10.0.128.26  

egressIP snat rules were there as prior to reboot nodes. EgressIP got assigned correctly.