Compression based on client

Yes, you can definitely do this. Here are some commands that you could use to help determine the type of client. We have been working on improving some of them in 9.0.5, so you may want to hold off on getting too elaborate with them until then.

IP::hops

This gives you the estimated number of hops the peer takes to get to you.

TCP::rtt

This gives you the smoothed round-trip time estimate between you and the peer. Note that as an implementation detail, the unit is in 1/32 of a millisecond. (Sorry, that's a kernel implementation detail we had to use to avoid floating point.)

Note that the rtt takes some time to converge, so we have the following in order to cull outliers:

ROUTE::rttvar

This is the statistical variance of rtt in 1/16 ms intervals.

TCP::bandwidth

This is an estimate of the upload bandwidth (i.e. how much data we can optimally push to the peer without causing recoveries or drops) in bytes per second. Note: due to a bug in our implementation, this value is incorrect in current releases. It has been fixed for 9.0.5.

And, as you mentioned, we of course have:

TCP::mss

With these metrics, you can imagine just how good the possibilities are for traffic analysis. Of course, you can also use things like

IP::tos

To both get and set the diffserv parameters for traffic, if you have upstream devices doing traffic classification for you.

Here is a simple rule example using TCP::mss that disables compression to larger MSS clients (you must have it enabled on the profile, so the rule can only disable it.)

 
    when HTTP_REQUEST { 
        if { [TCP::mss] >= 1280 } { 
            COMPRESS::disable 
        } 
    } 
 

Let us know how it goes, and please feel free to post your suggestions and enhancements!

I thank you for the reply. I will see what I can do.

 

I tried the following and got the following error. How do I change the HTTP profile?

 

 

 

 

when CLIENT_DATA {

 

if { [TCP::rtt] >= 1000 } {

 

profile HTTP_maxcompress

 

} elseif { [TCP::rtt] >= 500 } {

 

profile HTTP_mincompress

 

} else {

 

profile HTTP

 

}

 

}

 

 

01070151:3: Rule [Rap_iRule] error:

 

line 3: [undefined procedure: profile] [profile HTTP_maxcompress]

We don't allow you to switch http profiles from rules. If you are trying to set the compression level dynamically, you may be able achieve the same thing using this rule

COMPRESS::gzip level [ 1 .. 10 ]

where '9' is a value at which you get the highest level of compression. You can call this rule as many times as you like and the value is sticky for the life time of that connection.

I think you want to latch HTTP_REQUEST rather than CLIENT_DATA. CLIENT_DATA occurs after a TCP::collect rule, which may or may not have triggered any HTTP events. The safest place to check this metric is in HTTP_REQUEST.

Correction, the rule should read

COMPRESS::gzip level [ 1 .. 9 ]

Actually, I would have preferred '11' but oh well.

Hi,

 

 

Can you confirm if the F5 LB's support the option to route traffic based on a diffserve value? I would look to have the value set by another system downstream.

 

 

Thanks

 

 

Marc

Yes, if you use the IP::tos and/or LINK::qos

 

 

http://devcentral.f5.com/wiki/default.aspx/iRules/IP__tos.html Click here

 

 

http://devcentral.f5.com/Wiki/default.aspx/iRules/LINK__qos.html Click here

Thanks very Much