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Cisco IOS Software Releases 12.1 Mainline

Field Notice: NAT Enabled Routers Encounter Problems with Cisco IOS 12.1(5)T


May 4, 2001


Products Affected

Product

Comments

Cisco IOS Releases: 12.1(5)T, 12.1(5)T1 12.1(5)T2, 12.1(5)T3, 12.1(5)T4, 12.1(5)T5, 12.1(5)T6

All products supported in Cisco IOS Release 12.1T utilizing the feature - Network Address Translation (NAT).

Problem Description

Cisco routers with NAT enabled may unexpectedly restart if non-Skinny traffic uses port 2000 when using affected Cisco ® IOS releases.

This problem is tracked with the defect ID CSCds72170 (registered customers only) .

Background

When NAT is enabled with affected Cisco IOS releases the router may experience unexpected forced software reloads.

NAT Skinny support listens on TCP port 2000, which is used by Cisco Call Manager to translate the embedded IP address and port information. Since this is not a registered port, there are other applications which might be using it. NAT treats this as a special port and will try to parse the packet when an application uses port 2000, which might lead to an unexpected forced software reload. This will affect only the customers who have NAT configured on their routers.

Problem Symptoms

The output of the show version and show stacks commands after the system reloaded from the defect CSCds72170 are as follows:

show version

Cisco Internetwork Operating System Software
IOS (tm) 7200 Software (C7200-IS-M), Experimental Version 12.1(20001113:182553) 
[hsiang-1215tcap 101] 
Copyright (c) 1986-2000 by cisco Systems, Inc. 
Compiled Tue 14-Nov-00 19:05 by hsiang 
Image text-base: 0x60008960, data-base: 0x61318000 


ROM: System Bootstrap, Version 12.0(19990210:195103) [12.0XE 105], DEVELOPMENT SOFTWARE 
BOOTFLASH: 7200 Software (C7200-BOOT-M), Version 12.0(10)S, EARLY DEPLOYMENT RELEASE SOFTWARE (fc1) 


router uptime is 40 minutes 
System returned to ROM by bus error at PC 0x60C96000, address 0xD4093640 at 19:31:50 UTC Wed Nov 15 2000 
System restarted at 19:33:42 UTC Wed Nov 15 2000 
System image file is "slot0:c7200-is-mz.1215t"

show stacks

Minimum process stacks: 
Free/Size Name 
7288/12000 Init
11332/12000 Router Init 
5292/6000 RADIUS INITCONFIG 
8044/9000 DHCP Client 
9660/12000 Virtual Exec


Interrupt level stacks: 
Level Called Unused/Size Name 
1 35960166 7808/9000 Network interfaces 
2 0 9000/9000 DMA/Timer Interrupt 
3 1 8644/9000 PA Management Int Handler 
4 608 8640/9000 Console Uart 
5 0 9000/9000 OIR/Error Interrupt 
7 608498 8604/9000 NMI Interrupt Handler
 

System was restarted by bus error at PC 0x60C96000, address 0xD4093640 at 19:31:50 UTC Wed Nov 15 2000 
7200 Software (C7200-IS-M), Experimental Version 12.1(20001113:182553) [hsiang-1 215tcap 101] 
Compiled Tue 14-Nov-00 19:05 by hsiang 
Image text-base: 0x60008960, data-base: 0x61318000 


Stack trace from system failure: 
FP: 0x6249DEA8, RA: 0x60C96000 
FP: 0x6249DEF8, RA: 0x60C96E44 
FP: 0x6249DFB0, RA: 0x60C82D64 
FP: 0x6249DFD0, RA: 0x60C83248 
FP: 0x6249E030, RA: 0x6079AC30
FP: 0x6249E0A0, RA: 0x6079AEF8
FP: 0x6249E0C8, RA: 0x6079B074
FP: 0x6249E100, RA: 0x606A23E4

Workaround/Solution

No workaround is available.

Solution for CSCds72170

Cisco IOS Major Release

Cisco IOS Maintenance Release

Cisco IOS Images

CCO Availability

12.1T

12.1(5)T7

All images

April 24, 2001

12.2

12.2(1)

All images

May 2, 2001

DDTS

DDTS

Description

CSCds72170 (registered customers only)

Cisco routers with NAT enabled will unexpectedly restart if non-Skinny traffic uses port 2000.

Cisco IOS Versions Affected

The CSCds72170 affected Cisco IOS images will be removed from CCO and will not be available with new orders.

Cisco IOS Major Release

Cisco IOS Maintenance Releases

Cisco IOS Images

Removed From CCO

12.1T

12.1(5)T, 12.1(5)T1, 12.1(5)T2, 12.1(5)T3, 12.1(5)T4, 12.1(5)T5, 12.1(5)T6

All images

April 24, 2001

How To Upgrade Software

Maintenance Solution:

To obtain the next maintenance release, follow the instructions below:

Software Downloading from CCO via World Wide Web (registered customers only)

Go to Software Downloading Process (registered customers only)

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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