Different behaviour for L3, L4, L5 rules

[yves.haemmerli]

If I manually suspend a service using the suspend command, is it true that the CSS behaviour is different whether the service is in a Layer 3,4 or 5 content rule ?

I read that if the service in a Layer-3 or 4 content rule, existing sessions continue to flow on the suspended service, but is the service is in a Layer-5 content rule, existing sessions will be reset by the CSS. Is it a true statement ?

If yes, what can be done to allow existing sessions to continue to flow until they naturally terminate ?

Thank you,

Yves Haemmerli

[seilsz]

Hi Yves,

The answer to your first two (2) questions is 'Yes'.

If you are running WebNS version 7.30+, you can set the service weight to zero (0) to bleed existing connections off.

~Zach

[yves.haemmerli]

Hi Zach,

Thank you for your answer. However, I have some trouble to understand how it really works...

In a L5 flow, a single TCP session can carry several GET requests with HTTP 1.1.

Do you mean that the CSS will reset the established TCP session if I manually suspend the service ? Why this change in behaviour compared with a L4 flow, where the TCP sessions are kept established until they close themselves with a FIN ??

I would really appreciate your feedback

Thank you,

Yves

[seilsz]

Hi Yves,

The service state is checked each time the CSS makes a load balancing decision. So for L3/4 rules, this happens with the initial TCP SYN packet. With L5 rules, this happens with each HTTP GET. So each HTTP request received on a L5 rule is subject to load balancing, and hence a check of the service state. If the service has been suspended since the last request, the connection must be reset/remapped.

Please let me know if you have any additional questions.

Regards,

Zach

[yves.haemmerli]

Hi Zach,

This makes more sense for me now, thank you for your help. However, as I am using Arrowpoint cookie stickyness, I then assume that once a new TCP session has been established, the CSS will ignore the cookie in the next GET request (because it correspond to a suspended service) and assign a new cookie that corresponds to an active service, right ?

Thanks again Zach

Yves

[seilsz]

Your assumption is correct, Yves. If the service associated with the client-provided cookie is down, the CSS will use the configured balance method to use another service.

~Zach