Field Notice: FN - 63088 - WAAS Version 4.0.15 Removed from CCO - Please Upgrade to Version 4.0.17

March 18, 2008

NOTICE:

THIS FIELD NOTICE IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTY OF MERCHANTABILITY. YOUR USE OF THE INFORMATION ON THE FIELD NOTICE OR MATERIALS LINKED FROM THE FIELD NOTICE IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS FIELD NOTICE AT ANY TIME.

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Revision History

Revision	Date	Comment
1.0	18-MAR-2008	Initial Public Release

Products Affected

Products Affected
WAAS - 4.0(15)

Problem Description

There are several severe defects introduced in version 4.0.15 :

- Stale TCP connections appear to be active and optimized even after the client and server have closed connections. As a consequence, subsequent connections are put into pass-through due to a falsely detected overload condition.

- The WAE shows CPU usage spikes and performance appears to be affected.

Background

Several severe defects have been detected in the 4.0.15 code. In the interest of our customers, Cisco has removed this version of code from CCO.

Problem Symptoms

Several potential problem symptoms may be observed using the 4.0.15 version:

CSCsm22514

The optimized TCP connections can appear "stuck" in the WAE after the connection has been closed by the client and server. The symptoms for this issue include the following:

- The optimized connection only appears in the client-side WAE.

- The read and write states for the client-side original connection are both "Close".

- The read state for the client-side optimized connection is "Read Shutdown".

- The write state for the client-side optimized connection is "D. Write Wait".

- The optimized connection read and work buffers contain data, usually 5 to 10 bytes.

CSCsm46924

- TCP flows appear to be active but a trace on the client and/or server do not show any TCP keepalives but the flows still persist in the WAE.

CSCsm51361

- Stale TCP connections on a WAAS device will appear to be optimized, and subequently force connections to go into Passthrough as the WAAS will be in an overload state. The connections are truly no longer active; the output of show tfo connection will show:

Current Read State: Close Close 
Previous Read State: Read Shutdown Read Shutdown 
Current Write State: Close Close 
Previous Write State: Write Shutdown Write Shutdown

CSCsm54004

- CPU spikes, up to 100% CPU on multiple WAE devices.

Workaround/Solution

Upgrade to 4.0.17 or a more recent version of WAAS software. The software can be found on cisco.com at the following location:

Cisco WAAS 4.0 Software Download Page (registered customers only)

Instructions for upgrading the software can be found on cisco.com in the following location:

Release Note for Cisco Wide Area Application Services (Software Version 4.0.15 and 4.0.17)

If immediate upgrade is not possible, try restarting tcp proxy using the CLI command service restart tcpproxy when the problem is seen. If the problem persists then reboot the WAE.

DDTS

To follow the bug ID link below and see detailed bug information, you must be a registered user and you must be logged in.

DDTS	Description
CSCsm22514 (registered customers only)	Optimized TCP connections appear "stuck" in the WAE after the connection has been closed by the client and server.
CSCsm46924 (registered customers only)	Flows persisted on the WAE even though both client and server had shutdown the connection.
CSCsm51361 (registered customers only)	Stale TCP connections on a WAAS device appear to be active and optimized, putting the WAAS in an overload state. Subsequent connections are forced into Passthrough mode. The connections are truly no longer active; the output of the CLI command show tfo connection displays: Current Read State: Close Close Previous Read State:Read Shutdown Read Shutdown Current Write State:Close Close Previous Write State:Write Shutdown Write Shutdown
CSCsm54004 (registered customers only)	The WAE shows CPU usage spikes and performance appears to be affected. The tcpproxy appears to be using most of the CPU resources for a period of time.

For More Information

If you require further assistance, or if you have any further questions regarding this field notice, please contact the Cisco Systems Technical Assistance Center (TAC) by one of the following methods:

• Open a service request on Cisco.com
• By email
• By telephone

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