Description of problem:

without BGP UDN advertised: 

UDN pod cannot access default network by nodePort service with ETP=local on same node

After BGP UDN advertised to default VRF

UDN pod can access default network by nodePort service with ETP=local on same node

# oc rsh -n z9 test-rc-ncfg7 ip a 
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0@if154: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1400 qdisc noqueue state UP group default 
    link/ether 0a:58:0a:81:02:14 brd ff:ff:ff:ff:ff:ff link-netnsid 0
    inet 10.129.2.20/23 brd 10.129.3.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fd01:0:0:5::14/64 scope global 
       valid_lft forever preferred_lft forever
    inet6 fe80::858:aff:fe81:214/64 scope link 
       valid_lft forever preferred_lft forever
3: ovn-udn1@if155: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1300 qdisc noqueue state UP group default 
    link/ether 0a:58:28:64:02:05 brd ff:ff:ff:ff:ff:ff link-netnsid 0
    inet 40.100.2.5/24 brd 40.100.2.255 scope global ovn-udn1
       valid_lft forever preferred_lft forever
    inet6 fe80::858:28ff:fe64:205/64 scope link 
       valid_lft forever preferred_lft forever


 oc get pod -n z9 -o wide
NAME            READY   STATUS    RESTARTS   AGE   IP            NODE                                 NOMINATED NODE   READINESS GATES
test-rc-gg5d2   1/1     Running   0          17h   10.128.2.31   worker-0.core.openshift-qe.sdn.com   <none>           <none>
test-rc-ncfg7   1/1     Running   0          17h   10.129.2.20   worker-2                             <none>           <none> 

####there is nodePort svc with ETP=local on default network namespace z0 #

# oc get svc -n z0 hello-pod -o yaml
apiVersion: v1
kind: Service
metadata:
  creationTimestamp: "2025-03-06T02:49:04Z"
  labels:
    name: hello-pod
  name: hello-pod
  namespace: z0
  resourceVersion: "676086"
  uid: 46b4191b-bec4-4aa8-97fc-fa6035e8382e
spec:
  clusterIP: 172.30.225.251
  clusterIPs:
  - 172.30.225.251
  externalTrafficPolicy: Local
  internalTrafficPolicy: Cluster
  ipFamilies:
  - IPv4
  ipFamilyPolicy: SingleStack
  ports:
  - name: http
    nodePort: 32705
    port: 27017
    protocol: TCP
    targetPort: 8080
  selector:
    name: test-pods
  sessionAffinity: None
  type: NodePort
status:
  loadBalancer: {}

********************

############without BGP UDN adverstie,  udn can access nodeport with different network on different node. but not different network on same node. see case 8 and 9 in https://docs.google.com/document/d/12ITKApvttTi2AO0bYGVwZGXFazLBNTcoLlmNmIXs9zI/edit?tab=t.0

# oc get pod -n z0 -o wide
NAME            READY   STATUS    RESTARTS   AGE   IP            NODE                                 NOMINATED NODE   READINESS GATES
test-rc-772wm   1/1     Running   0          17h   10.129.2.24   worker-2                             <none>           <none>
test-rc-dw7ww   1/1     Running   0          17h   10.128.2.32   worker-0.core.openshift-qe.sdn.com   <none>     
      <none>
# oc rsh -n z9 test-rc-ncfg7 curl 192.168.111.25:32705
^Ccommand terminated with exit code 130

# oc rsh -n z9 test-rc-ncfg7 curl 192.168.111.23:32705
Hello OpenShift!


######## After UDN advertised both two can be accessed on SGW #############

# oc rsh -n z9 test-rc-ncfg7 curl 192.168.111.23:32705
Hello OpenShift!

# oc rsh -n z9 test-rc-ncfg7 curl 192.168.111.25:32705
Hello OpenShift!

Version-Release number of selected component (if applicable):

How reproducible:

Steps to Reproduce:

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Additional info:

Please fill in the following template while reporting a bug and provide as much relevant information as possible. Doing so will give us the best chance to find a prompt resolution.

Affected Platforms:

Is it an

1. internal CI failure
2. customer issue / SD
3. internal RedHat testing failure

If it is an internal RedHat testing failure:

• Please share a kubeconfig or creds to a live cluster for the assignee to debug/troubleshoot along with reproducer steps (specially if it's a telco use case like ICNI, secondary bridges or BM+kubevirt).

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• What is the traffic path? (examples: pod2pod? pod2external?, pod2svc? pod2Node? etc)

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    • What is the dstNode, dstNamespace, dstPodName and dstPodIP?
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  • If it is not a connectivity issue:
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