{"id":589,"date":"2011-09-16T22:58:39","date_gmt":"2011-09-16T22:58:39","guid":{"rendered":"https:\/\/fir3netwp.gmsrrpobkbd.com\/2011\/09\/16\/upgrading-to-cisco-css-820303-or-higher-results-in-slow-network-performance\/"},"modified":"2023-02-24T08:59:59","modified_gmt":"2023-02-24T08:59:59","slug":"upgrading-to-cisco-css-820303-or-higher-results-in-slow-network-performance","status":"publish","type":"post","link":"https:\/\/www.fir3net.com\/Loadbalancers\/Cisco\/upgrading-to-cisco-css-820303-or-higher-results-in-slow-network-performance.html","title":{"rendered":"Upgrading to Cisco CSS 8.20.3.03 (or higher): Slow Network Performance"},"content":{"rendered":"

Symptoms<\/strong><\/h2>\n

Slow network performance when accessing back-end servers through a Cisco CSS running 8.20.3.03 (or higher).<\/p>\n

Background<\/strong><\/h2>\n

Cisco CSS 8.20.3.02 (and lower) did not support window scaling. This meant that the initial window scale option announced within the 3 way handshake was not propagated to the server.
\nThis issue was resolved within 8.20.3.03 (CSCsk92868), however even though the initial window scale (WS) option is propagated to the back-end server, the WS response from the back-end server is cleared and set to 0 by the CSS.<\/p>\n

Below shows this behaviour (via the 3 way handshake):<\/p>\n

CLIENT.3202 > SERVER.80: Flags [S], cksum 0xf7eb (correct), seq 1112270373, win 65535, options \r\n[mss 1260,nop,wscale 1<\/strong>,nop,nop,sackOK], length 0\r\nSERVER.80 > CLIENT.3201: Flags [S.], cksum 0x5d1b (correct), seq 2130167885, ack 33254730, win \r\n8760, options [mss 1380,wscale 0<\/strong>,eol], length 0<\/pre>\n
This results in a breakdown in the announcement of the TCP window size and in turn network delays.<\/p>\n
Solution<\/strong><\/h2>\n
In resolve this issue there are 2 configuration options available (based on your CSS software level):<\/p>\n