Application Delivery (ADX)

Posts: 27
Registered: ‎05-04-2009

How do I configure DSR together with CSW?

I had no luck configuring this.

Super Contributor
Posts: 316
Registered: ‎05-01-2009

Re: How do I configure DSR together with CSW?

DSR and CSW - I guess you would like to do Layer 7 Switching together with DSR.

I am sorry but this is not possible. This is NOT a restriction of the ServerIron/ADX - it is some kind of general protocol related restriction. All Layer 7 Switching feature do require some kind of "delayed binding". A TCP sessions needs to be terminated at the ServerIron first of all to have a look at the initial data packets. The content (layer 7) of these packets is getting used to select a real server and the connection is getting forwarded to the real server at this time but not earlier. There are basically two connections:

1. client -> ServerIron

2. ServerIron -> real server

The ServerIron needs to establish its connection after a few client packets. The ServerIron is using the client's IP address to do so. The 3-way handshake is not going to be successful in case you try to do this in a DSR setup. The server is going to reply directly to the client instead of sending the replies back to the ServerIron - this is the problem.

Additionally you would have problems in case you are going to rewrite/change layer 7 content - this implies that sequence numbers need to change etc. - the ServerIron/ADX needs to get ALL packets coming from the client and from the server because a seq# change influence all packets in a TCP connection. DSR is therefore unfortunately not possible with Layer 7 stuff but this is a general limitation as mentioned already.

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