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Cisco MGX 8230 Software

Field Notice: MGX 1.2.02 Foresight ABR Connections Drop Cells


February 5, 2003


Products Affected

Product

Comments

MGX-FRSM-2CT3

With MGX 1.2.01 or MGX 1.2.02 software releases

MGX-FRSM-2T3E3

With MGX 1.2.01 or MGX 1.2.02 software releases

MGX-FRSM-HS2

With MGX 1.2.01 or MGX 1.2.02 software releases

MGX-FRSM-HS2/B

With MGX 1.2.01 or MGX 1.2.02 software releases

Problem Description

All Foresight Available Bit Rate (ABR) connections on the Frame Relay Service Module (FRSM) cards listed in the Products Affected section drops frames in the ingress direction when operating in an MGX8230, MGX8250 or MGX8850 (with PXM1) loaded with 1.2.01 or 1.2.02 MGX software.

Background

Upon upgrading the MGX-FRSM-2CT3, MGX-FRSM-2T3E3, MGX-FRSM-HS2, MGX-FRSM-HS2/B with 10.2.01, which is bundled into MGX 1.2.01 and MGX 1.2.02 releases, ABR Foresight connections are affected by not ramping up when network bandwidth is available, resulting in queue overflows in the ingress direction, causing frame discards due to exceeding the ingress queue depth.

This anomaly does not affect AX-FRSM-8T1, AX-FRSM-8T1-C, AX-FRSM-8E1, AX-FRSM-8E1-C, or AX-FRSM-HS1/B cards.

Problem Symptoms

Observing the channel statistics will indicate a loss of cells in the ingress direction. Network users would have intermittent or no access to remote services. Use the dspchancnt command to observe byte and frame discards.

Look for Rx (receive) Bytes and Frames discards because of exceeded queue depth in the receive direction.

ChanNum:          69
ChanState:        okay 

ChanUpTime:       10186
                                  Tx                            Rx
                             ---------------            ---------------
  AbitState:                 Sending A=1                Receiving A=1
  ATMState:                  Not sending any state      Not receiving any state
  Total Frames:              0                          0
  Total Bytes:               0                          0
  Frames DE:                 0                          0
  Bytes DE:                  0                          0
  Frames Discarded:          0                          0
  Bytes Discarded:           0                          0
  FramesDiscXceedQDepth:     0                    --->> 0 <<---
  BytesDiscXceedQDepth:      0                    --->> 0 <<---
  FramesDiscXceedDEThresh:   0                          0
  Frames FECN:               0                          0
  Frames BECN:               0                          0
  FramesTagged FECN:         0                          0
  FramesTagged BECN:         0                          0
  KbpsAIR:                   0                          0
  FramesTaggedDE:            0                          0
  BytesTaggedDE:             0                          0
  RcvFramesDiscShelfAlarm:                              0

Workaround/Solution

The workaround is to not use ABR connections with Foresight, and instead use Standard ABR. The solution is to upgrade MGX Software Releases 1.2.01 or 1.2.02 to MGX Software Release 1.2.1x or later.

DDTS

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DDTS

Description

CSCdx93715 (registered customers only)

foresight connections are not working properly

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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