Will changing the idle time value (default 4 minutes) on the ELB impact existing sessions?

Arkar Aung 0

Azure Load Balancer has a 4 minutes to 100-minutes timeout range for Load Balancer rules, Outbound Rules, and Inbound NAT rules.

Will chanting timeout value cause dropping existing session?

https://learn.microsoft.com/en-us/azure/load-balancer/load-balancer-tcp-idle-timeout?tabs=tcp-reset-idle-portal#set-the-tcp-idle-timeout-on-rules

Marcin Policht 11,230 Reputation points MVP

2024-04-23T22:13:10.76+00:00

That depends...

If the Load Balancer is configured to handle sessions in a stateful manner, changing the timeout value may not immediately affect existing sessions. Stateful session handling means that the Load Balancer keeps track of the state of connections and ensures that related packets are forwarded to the same destination. In this case, existing sessions may continue until they naturally expire or are terminated.

If the Load Balancer is configured to handle sessions in a stateless manner, changing the timeout value could potentially impact existing sessions. Stateless session handling means that each packet is handled independently, without maintaining state information. In this scenario, changing the timeout value may result in existing sessions being dropped or reset as the Load Balancer begins enforcing the new timeout.

For long-lived connections that remain active for a duration longer than the new timeout value, changing the timeout could lead to session termination or reset once the new timeout period is reached. This could affect applications or services that rely on persistent connections for their operation.

If the above response helps answer your question, remember to "Accept Answer" so that others in the community facing similar issues can easily find the solution. Your contribution is highly appreciated.

hth

Marcin
Marcin Policht 11,230 Reputation points MVP

2024-04-24T10:08:21.94+00:00

That depends...

If the Load Balancer is configured to handle sessions in a stateful manner, changing the timeout value may not immediately affect existing sessions. Stateful session handling means that the Load Balancer keeps track of the state of connections and ensures that related packets are forwarded to the same destination. In this case, existing sessions may continue until they naturally expire or are terminated.

If the Load Balancer is configured to handle sessions in a stateless manner, changing the timeout value could potentially impact existing sessions. Stateless session handling means that each packet is handled independently, without maintaining state information. In this scenario, changing the timeout value may result in existing sessions being dropped or reset as the Load Balancer begins enforcing the new timeout.

For long-lived connections that remain active for a duration longer than the new timeout value, changing the timeout could lead to session termination or reset once the new timeout period is reached. This could affect applications or services that rely on persistent connections for their operation.

If the above response helps answer your question, remember to "Accept Answer" so that others in the community facing similar issues can easily find the solution. Your contribution is highly appreciated.

hth

Marcin

1 answer

KapilAnanth-MSFT 35,246 Reputation points Microsoft Employee

2024-04-24T10:03:33.01+00:00

@Arkar Aung ,

Welcome to the Microsoft Q&A Platform. Thank you for reaching out & I hope you are doing well.

I shall check this internally and update this thread.

Cheers,

Kapil
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KapilAnanth-MSFT 35,246 Reputation points Microsoft Employee

2024-04-26T03:39:53.0833333+00:00

@Arkar Aung ,

I just got an update from our Product Team that

When the idle timeout value is changed, this will impact both new and existing connections.

The timer is reset to 0 and the newly set idle time-out value starts from the instant you update the time-out value.

Kindly let us know if this helps or you need further assistance on this issue.

Thanks,

Kapil

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