HTTP::header replace Irule

[root@ve1023:Active] config  b virtual bar list
virtual bar {
   snat automap
   pool foo
   destination 172.28.19.79:80
   ip protocol 6
   rules myrule
   profiles {
      http {}
      tcp {}
   }
}
[root@ve1023:Active] config  b pool foo list
pool foo {
   members {
      200.200.200.101:80 {}
      200.200.200.102:80 {}
   }
}
[root@ve1023:Active] config  b rule myrule list
rule myrule {
   when LB_SELECTED {
        if {[HTTP::host] equals "xxx.com"} {
                switch [LB::server addr] {
                        "200.200.200.101" { HTTP::header replace Host "yyy.com" }
                        "200.200.200.102" { HTTP::header replace Host "zzz.com" }
                }
        }
}
}

[root@ve1023:Active] config  ssldump -Aed -nni 0.0 port 80
New TCP connection 1: 172.28.19.253(40646) <-> 172.28.19.79(80)
1325589266.4184 (0.0038)  C>S
---------------------------------------------------------------
HEAD / HTTP/1.1
User-Agent: curl/7.15.5 (i686-redhat-linux-gnu) libcurl/7.15.5 OpenSSL/0.9.8r zlib/1.2.3 libidn/0.6.5
Host: xxx.com
Accept: */*
---------------------------------------------------------------

New TCP connection 2: 200.200.200.10(40646) <-> 200.200.200.101(80)
1325589266.4195 (0.0010)  C>S
---------------------------------------------------------------
HEAD / HTTP/1.1
User-Agent: curl/7.15.5 (i686-redhat-linux-gnu) libcurl/7.15.5 OpenSSL/0.9.8r zlib/1.2.3 libidn/0.6.5
Host: yyy.com
Accept: */*
---------------------------------------------------------------

[root@ve1023:Active] config  ssldump -Aed -nni 0.0 port 80
New TCP connection 1: 172.28.19.253(40648) <-> 172.28.19.79(80)
1325589291.8755 (0.0029)  C>S
---------------------------------------------------------------
HEAD / HTTP/1.1
User-Agent: curl/7.15.5 (i686-redhat-linux-gnu) libcurl/7.15.5 OpenSSL/0.9.8r zlib/1.2.3 libidn/0.6.5
Host: xxx.com
Accept: */*
---------------------------------------------------------------

New TCP connection 2: 200.200.200.10(40648) <-> 200.200.200.102(80)
1325589291.8766 (0.0009)  C>S
---------------------------------------------------------------
HEAD / HTTP/1.1
User-Agent: curl/7.15.5 (i686-redhat-linux-gnu) libcurl/7.15.5 OpenSSL/0.9.8r zlib/1.2.3 libidn/0.6.5
Host: zzz.com
Accept: */*
---------------------------------------------------------------