Latency when Pods communicate to coredns
Article ID: 336979
Updated On:
Products
VMware NSX
Issue/Introduction
This article can be used to find out the cause how latency happened
Symptoms:
Packets latency seen when pods communicate to coredns
Symptoms:
Packets latency seen when pods communicate to coredns
Environment
VMware NSX-T Data Center 2.5.x
VMware NSX-T Data Center
VMware NSX-T Data Center
Cause
1: Get Src Pod id
kubectl get pod
2: Get the tag (Privated vlan) that Pod is using
ovs-vsctl show
3: Get the switchport that Pod is using
net-stats -l
4: Do packet capture on this switchport
pktcap-uw --switchport --dir 2 -o pod.pcap
5: Example Packet analysis
The Src Pod did not send AAAA DNS query only A DNS query send the first time.
and after 5 seconds, it sent A and AAAA DNS query.
kubectl get pod
2: Get the tag (Privated vlan) that Pod is using
ovs-vsctl show
3: Get the switchport that Pod is using
net-stats -l
4: Do packet capture on this switchport
pktcap-uw --switchport --dir 2 -o pod.pcap
5: Example Packet analysis
The Src Pod did not send AAAA DNS query only A DNS query send the first time.
and after 5 seconds, it sent A and AAAA DNS query.
Resolution
Issue is not caused by nsx network
Workaround:
Add options in Pod resolv.conf
echo 'options single-request-reopen' >>/etc/resolv.conf
Workaround:
Add options in Pod resolv.conf
echo 'options single-request-reopen' >>/etc/resolv.conf
Additional Information
Impact/Risks:
5 Seconds latency when pods accessing coredns
5 Seconds latency when pods accessing coredns
Feedback
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