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Cisco IOS Software Releases 11.2

Field Notice: DLSw+ Defects in Cisco IOS 11.2(10.1),11.2(11.1), 11.2(13), 11.2(13.1)


Revised May 5, 1998

April 22, 1998


Description

This field notice describes several defects that exist in Cisco IOS 11.2 that potentially affect Data Link Switching (DLSw+) customers. All DLSw+ customers should review this Field Notice and the defects listed to determine if this affects your environment. If you believe you are in the population of customers that may be affected by the issues described in this field alert, Cisco Systems strongly recommends that you implement the workaround or solutions outlined below.

Cisco Systems, Inc., strives to maintain the highest software quality standards in the internetworking industry. We also seek to provide you, our customers and partners, with the most thorough and advanced software quality information as part of the service available under your Cisco service agreement.

Products Affected

The DLSw+ feature in the following Cisco IOS releases are affected:

Cisco IOS Maintenance Releases:

  • Cisco IOS Maintenance Release 11.2(11) through 11.2(13)

  • Cisco IOS Maintenance Release 11.2(11)P through 11.2(13)P

  • Cisco IOS Maintenance Release 11.3(2)

  • Cisco IOS Maintenance Release 11.3(2)T

  • Cisco IOS Early Deployment Release11.2(11)BC

  • Cisco IOS Early Deployment Release11.3(2)XA

Cisco IOS Interim Builds:

  • Cisco IOS Interim Build 11.2(10.1) through 11.2(13.1)

  • Cisco IOS Interim Build 11.2(10.1)P through 11.2(13.1)P

  • Cisco IOS Interim Build 11.3(1.1) through 11.3(1.6)

  • Cisco IOS Interim Build 11.3(1.1)T through 11.3(1.6)T

Problem Description

Unexpected DLSw+ behaviors started to appear in releases 11.2(10.1), 11.2(10.01)P, 11.3(1.1), 11.3(1.1)T, 11.2(11)BC, 11.3(02)XA. The following bugs are serious DLSw defects and should be reviewed: CSCdj80747, CSCdj93178, and CSCdk01667.

Bug Details

View bug details for CSCdj80747 (registered customers only)

View bug details for CSCdj93178 (registered customers only)

View bug details for CSCdk01667 (registered customers only)

Description of DLSw+ Defect CSCdj93178

It has been determined that APPC, APPN [PU2.1], and SNA Subarea [PU4] traffic may suffer from poor performance in some environments. Under certain circumstances it is possible for the DLSw+ pacing window value (CW) to increase and eventually exceed the max-pacing value. This occurs when either the default max-pacing of 50 is used or a value is configured manually.

This behavior is only likely to be seen in environments where large data transfers occur when using large pacing windows at the higher layers. The main symptom of this problem is that APPC, APPN [PU2.1] and SNA Subarea [PU4] sessions perform slowly. This does not affect PU2-PU4 sessions (LU2 terminal traffic including IND$FILE transfers) nor does it affect NetBIOS traffic.

Description of DLSw+ Defect CSCdk01667

APPN and DSPU over Data Link Switching (DLSw+) may experience the inability to activate LU sessions.

Customers running APPN or DSPU over DLSw+ may experience problems activating LU sessions when the DLSw+ dlsw local-peer command init-pacing-window and max-pacing-window parameters are set at the default of 20.

Description of DLSw+ Defect CSCdj80747

SNA sessions over a Data Link Switching (DLSw+) circuit may stop passing data after a data transfer occurs.

Depending upon the rate at which a data transfer occurs, the transmit window size slips causing an imbalance between the granted_units of one peer and another. This results in the two peers no longer being able to pass data and the SNA session will hang. The main symptom of this problem is that individual DLSw+ sessions can hang.

Workarounds

A workaround to CSCdj93178 is to recycle the link session, either by doing it from the station (using vary net,inact,...) or on the Router using the command :

  clear dlsw circuit <circuit-index>

The circuit index is obtained from the output of the command:

  show dlsw circuit detail mac <mac-address>

While a workaround to CSCdk01667 is available, Cisco Systems strongly recommends that you work with the Technical Assistance Center before changing flow control values. The work around to CSCdk01667 is to change the dlsw local-peer command init-pacing-window and max-pacing-window parameters from the default setting to a number greater than 20.

  dlsw local-peer peer-id xxx.xxx.xxx.xxx init-pacing-window 1000 max- pacing-window 2000

A workaround to CSCdj80747 is to clear the session in one form or another. You can either deactivate --> reactivate the PU within VTAM or clear dlsw circuits <circuit id> on one of the routers.

  dlsw local-peer peer-id xxx.xxx.xxx.xxx init-pacing-window 1000 max- pacing-window 2000

A workaround to CSCdj80747 is to clear the session in one form or another. You can either deactivate --> reactivate the PU within VTAM or clear dlsw circuits <circuit id> on one of the routers.

Solutions

To eliminate the problems described in defects: CSCdj93178 and CSCdj80747, we recommend that you download and install 11.2(14) when it becomes available. Cisco Systems is still investigating defect: CSCdk01667. Until a final solution is available, please work with the Technical Assistance Center to implement a workaround.

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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