When configuring EgressIP using "matchLabels" it is working as expected, logical IP in Northbound container is equal to the number of pods using egressip.

But when we are using "matchExpressions" while configuring egressip, the result is not accurate. 
We are getting so many logical ips in Northbound container which are also being used by many other pods from other namespaces as well where we haven't assigned any egresssip.

1. Configure an egressip using the below YAML for expected result.
~~~
$ cat egressip.yaml 
apiVersion: k8s.ovn.org/v1
kind: EgressIP
metadata:
name: egressip-test
spec:
egressIPs:
- 10.74.191.100 
namespaceSelector:
  matchLabels:
    test: egressip
podSelector: {}
~~~

2. Configure an egressip using the below YAML for unexpected result.
~~~
apiVersion: k8s.ovn.org/v1
kind: EgressIP
metadata:
name: egress-matchexpression
spec:
egressIPs:
- 10.74.191.101
namespaceSelector:
  matchExpressions:
  - key: kubernetes.io/metadata.name
    operator: In
    values:
    - egress-test
~~~

- We are getting so many logical ips in Northbound container which are also being used by many other pods from other namespaces as well where we haven't assigned any egresssip. 
~~~
$ oc exec -it ovnkube-master-6hq4h -c northd -- ovn-nbctl show | grep -B1 -A3 "10.74.191.101" | grep 'external ip: "10.74.191.101"' | wc -l 
110 
~~~

- When configurong egressip using matchlabel, logical IP in Northbound container should be the number of pods using egressip.
~~~
$ oc exec -it ovnkube-master-6hq4h -c northd -- ovn-nbctl show  | grep -B1 -A3 "10.74.191.100" | grep 'external ip: "10.74.191.100"' | wc -l 
4
~~~

- After comparing the logical ips of Northbound container with other pods, observed that the defaults pods of openshift are also assigned these ips.
~~~
[quicklab@upi-0 ~]$ oc exec -it ovnkube-master-668tz -c northd -- ovn-nbctl show  | grep -B1 -A3 "10.74.191.101" 

    nat f86e9029-f8a0-4639-9e2a-7b3c839ec9cc
        external ip: "10.74.191.101"
        logical ip: "10.130.0.41"
        type: "snat"
    nat fb3a70fb-501a-4ad0-8999-f5826b77edad
        external ip: "10.74.191.101"
        logical ip: "10.128.0.37"
        type: "snat"
    nat fed1f3be-d244-4dee-9fbf-e615764529b8
        external ip: "10.74.191.101"
        logical ip: "10.130.0.19"
        type: "snat"
~~~

~~~
[quicklab@upi-0 ~]$ oc get pod -A -o wide | grep '10.130.0.19'
openshift-console                                  downloads-6498c8985f-x64nb                                                  1/1     Running     69 (2d1h ago)     2d16h   10.130.0.19     master-2.bmehraovn.lab.pnq2.cee.redhat.com   <none>           <none>

[quicklab@upi-0 ~]$ oc get pod -A -o wide | grep '10.128.0.37'
openshift-operator-lifecycle-manager               packageserver-6dbdbb9bc9-c4xm4                                              1/1     Running     357 (69m ago)     2d17h   10.128.0.37     master-1.bmehraovn.lab.pnq2.cee.redhat.com   <none>           <none>

[quicklab@upi-0 ~]$ oc get pod -A -o wide | grep '10.130.0.41'
openshift-controller-manager                       controller-manager-2jthr                                                    1/1     Running     5 (6h49m ago)     41h     10.130.0.41     master-2.bmehraovn.lab.pnq2.cee.redhat.com   <none>           <none>
~~~~