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Author: Admin | 2025-04-28
Is there an existing issue for this? I have searched the existing issuesVersionequal or higher than v1.17.1 and lower than v1.18.0What happened?when upgrading cilium from 1.16.7 to 1.17.0 or greater the mtu of multus attached interfaces gets changed causing connectivity issues there.How can we reproduce the issue?install cilium 1.16.7helm install cilium cilium/cilium --version 1.16.7 --namespace kube-system --set cni.exclusive=false --set cni.chainingMode=none --set operator.replicas=1setup ovs : install openvswitch on the cluster hosts and create a bridge (ovs-vsctl add-br br1)setup multus and ovs cni:kubectl apply -f https://github.com/kubevirt/cluster-network-addons-operator/releases/download/v0.98.1/namespace.yamlkubectl apply -f https://github.com/kubevirt/cluster-network-addons-operator/releases/download/v0.98.1/network-addons-config.crd.yamlkubectl apply -f https://github.com/kubevirt/cluster-network-addons-operator/releases/download/v0.98.1/operator.yamlecho '---apiVersion: networkaddonsoperator.network.kubevirt.io/v1kind: NetworkAddonsConfigmetadata: name: clusterspec: multus: {} ovs: {}' | kubectl apply -f -cat create a test pod and observe its mtu:cat mtu is 1500 for net1 mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:002: net1@if65994: mtu 1500 qdisc noqueue state UP mode DEFAULT group default link/ether ce:3c:94:e8:b2:f3 brd ff:ff:ff:ff:ff:ff link-netnsid 065992: eth0@if65993: mtu 1450 qdisc noqueue state UP mode DEFAULT group default qlen 1000 link/ether fe:af:d8:3a:89:90 brd ff:ff:ff:ff:ff:ff link-netnsid 0">[root@pod-case-01 /]# ip link1: lo: mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:002: net1@if65994: mtu 1500 qdisc noqueue state UP mode DEFAULT group default link/ether ce:3c:94:e8:b2:f3 brd ff:ff:ff:ff:ff:ff link-netnsid 065992: eth0@if65993: mtu 1450 qdisc noqueue state UP mode DEFAULT group default qlen 1000 link/ether fe:af:d8:3a:89:90 brd ff:ff:ff:ff:ff:ff link-netnsid 0update cilium to 1.17.xhelm upgrade cilium cilium/cilium --version 1.17.1 --namespace kube-system --set cni.exclusive=false --set cni.chainingMode=none --set operator.replicas=1now mtu is 1450 for this interface: mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:002: net1@if65994: mtu 1450 qdisc noqueue state UP mode DEFAULT group default link/ether ce:3c:94:e8:b2:f3 brd ff:ff:ff:ff:ff:ff link-netnsid 065992: eth0@if65993: mtu 1450 qdisc noqueue state UP mode DEFAULT group default qlen 1000 link/ether fe:af:d8:3a:89:90 brd ff:ff:ff:ff:ff:ff link-netnsid 0">[root@pod-case-01 /]# ip link1: lo: mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:002: net1@if65994: mtu 1450 qdisc noqueue state UP mode DEFAULT group default link/ether ce:3c:94:e8:b2:f3 brd ff:ff:ff:ff:ff:ff link-netnsid 065992: eth0@if65993: mtu 1450 qdisc noqueue state UP mode DEFAULT group default qlen 1000 link/ether
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