Bug ID 421948: BIG-IP keeps sending ICAP request after server response is done.

Last Modified: Nov 22, 2021

Affected Product(s):
BIG-IP LTM(all modules)

Known Affected Versions:
11.3.0, 11.4.0, 11.4.1

Fixed In:
11.5.0, 11.4.1 HF6

Opened: May 28, 2013

Severity: 3-Major

Related Article: K15593


If after receiving the preview the ICAP server returns 200-ok with an encapsulaed HTTP 302 redirect response, the BIG-IP system would continue sending the request body until its outgoing TCP window is drained as a result of the connection closing. The superfluous data flow to the server consumes resources longer than necessary which can cause performance loss.


Superfluous data flow from BIG-IP system to ICAP server, resulting in some performance degradation.


ICAP server with preview returns HTTP 302 redirect.


The ICAP server can ignore any trailing request data.

Fix Information

BigIP stops sending the ICAP request body immediately it sees the end of the ICAP server's response. If the end of the response is in the same frame as the 200-ok (which is normally the case for a short HTTP response like 302 redirect), no more bytes are sent beyond what was sent in the preview and the performance impact is eliminated (otherwise data might resume very briefly with less performance impact than before).

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips