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Cisco Wide Area Application Services (WAAS) Software

Field Notice: FN - 63778 - WAAS Version 5.1.1e Removed from Cisco.com Due to a DRE Defect - Use Version 5.1.1f

Field Notice: FN - 63778 - WAAS Version 5.1.1e Removed from Cisco.com Due to a DRE Defect - Use Version 5.1.1f

March 12, 2014


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.

Revision History

Revision Date Comment
1.0
12-MAR-2014
Initial Public Release

Products Affected

Products Affected
WAAS - 5.1.1e

Problem Description

Wide Area Application Services (WAAS) Version 5.1.1e has been pulled from Cisco.com due to a Data Redundancy Elimination (DRE) defect which causes the DRE process to crash and core dump. The process restarts and continues to write a core which could cause the disc drive to fill. This means the WAAS device goes into bypass mode and traffic is no longer being optimized.

Background

A severe defect with regards to DRE was found in WAAS version 5.1.1e. In the best interest of our customers, version 5.1.1e is not recommended for any deployments and has been removed from the software library on Cisco.com.

Problem Symptoms

These scenarios could cause the DRE problem to manifest:

  • Sometimes in network transmissions, the DRE module encounters processing wrong packets. Wrong packets are mainly due to TCP checksum collisions. Decode of these packets fails and results in DRE core and process restart.

  • In the DRE, the data lookup for some signature might fail as the similar data unit has been flushed out of cache. This might be due to low DRE cache size or large concurrent connections that transfer different data. This lookup failure triggers an assert and that results in a core file and the DRE process restart.

  • While it handles a large number of concurrent connections with a large amount of compressible data, the DRE might run out of memory for the buffer allocation that is required in the decode process. This triggers an assert and results in a core file and DRE process restart.

  • When the total connections handled by DRE exceeds the WAN acceleration engine (WAE)'s supported connection limit, the DRE core and DRE process restart. 

The core file is created because it hit the development ASSERT check in the code base. Otherwise, all of these scenarios are handled appropriately.

In order to determine what version you have, enter this command:

Lab-edge#show version
Cisco Wide Area Application Services Software (WAAS)
Copyright (c) 1999-2013 by Cisco Systems, Inc.
Cisco Wide Area Application Services (universal-k9) Software Release 5.1.1e
 (build b13 Jan 29 2014)
Version: oe7341-5.1.1e.4
Compiled 20:57:42 Jan 29 2014 by gpadhi
Device Id: 00:1a:64:64:b2:4c
System was restarted on Thu Feb 6 09:11:26 2014.
System restart reason: called via cli.
The system has been up for 2 weeks, 5 days, 4 hours, 54 minutes, 41 seconds.
Lab-edge#

Workaround/Solution

There is no proposed workaround for this problem in version 5.1.1e. This defect is fixed in the 5.1.1f release version that is available on Cisco.com.

Version 5.1.1f is posted in WAAS Software Download Center (registered customers only).

See the WAAS Configuration Guide for installation instructions.

DDTS

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

DDTS Description
CSCum77623 (registered customers only) WAAS - so_dre created a core file.

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:

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