Conditions for "session-reuse" to work

[yves.haemmerli]

Hi,

I try to make session-reuse working on an ACE-4710 Version A5(1.0) without success. Actually, I am facing the problem of the high number of backend HTTP connections that must pass through a firewall. I want to reduce this amount of open sessions with real servers by allowing the ACE to establish permament TCP connections with each rserver.  However, it does not work as I expected. I still see individual TCP sessions established and closed after each GET - 200OK exchange.

The parameter-map I have to enable this feature is as follows :

parameter-map type http PERF_YHA_HTTP_PARAM

  persistence-rebalance

  set header-maxparse-length 65535

  set content-maxparse-length 65535

server-conn reuse

Note : I use PAT, on the backend, as required by the session-reuse feature

My questions are the followings :

1. How many sessions the ACE would establish with a specific rserver ? only one ? one per TCP option set ?
2. How much time a backend session would last if kept idle for a certain time ?
3. What End Points must share the same TCP options to make sure session-reuse works ? Client to ACE ? ACE to rserver ? all together ?

Thank you for any help in this regard

Yves

[ajayku2]

Hi,

"I still see individual TCP sessions established and closed after each GET - 200OK exchange"

Looking at the above statement it seems you are using HTTP 1.0 or the connection which you are observing are Probes sent by ACE.

For session reuse to work you should use HTTP 1.1

regards,

Ajay Kumar

[yves.haemmerli]

Hi Ajay,

Thank you for your comment. We use HTTP 1.1 of course, so the problem is not here.

By reading the ACE documentation, one can read the following :

"... The ACE maintains a pool of TCP connections based on TCP options. New client connections can reuse those connections in the pool if the new client connections and prior server connections share the same TCP options... "

"... To ensure proper operation of this feature, follow these TCP server reuse recommendations and restrictions:  Ensure that the ACE maximum segment size (MSS) is the same as the server MSS..."

So I suspect that the problem is related to MSS and TCP options. But still, I do not understand where the TCP MSS and options should match :

• Between the client and the ACE ?
• Between the ACE and the Server ?
• End to end on both client and server sessions ?

Thank you for your help

Yves

[ajayku2]

Hi,

It should be end to end also ACE does not allow option header by default. Please use parameter map to allow option header.

regards,

Ajay Kumar