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Cisco BPX 8600 Series Switches

Bad Grant Errors

Document ID: 10812

Updated: Dec 06, 2006

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Introduction

A Bad Grant error is logged after a card waits 32 frame cycles to transmit a BFrame and does not get a grant. The polling algorithm is such that the longest wait is less than 16 cycles.

Prerequisites

Requirements

There are no specific requirements for this document.

Components Used

This document is not restricted to specific software and hardware versions.

Conventions

Refer to the Cisco Technical Tips Conventions for more information on document conventions.

How do I see them?

When you issue the command dspsloterrs, you can see which cards log slot errors, as shown in this section. You can also issue the command dspsloterrs <card #> to zoom in on any one card.

bpx1           TN    Cisco           BPX 8620  9.3.51    Mar. 18 2005 17:16 GMT 

                        Summary of Slot Errors

           Invld Poll  Poll        Tx    Rx          B-    Rx
     Stdby Rx    A Bus B Bus Bad   BIP-  BIP-  SIU   Frame FIFO  Poll  CK-
     PRBS  Port  Par   Par   Grant 16    16    Phase Par   Sync  Clk   192
Slot Errs  Errs  Errs  Errs  Errs  Errs  Errs  Errs  Errs  Errs  Errs  Errs 
1        0     0     0     0     0     0     0     0     0     0     0     0
2        0     0     0     0     0     0     0     0     0     0     0     0
3        0     0     0     0     0     0     0     0     0     0     0     0
4        0     0     0     0     0     0     0     0     0     0     0     0
5        0     0     0     0     0     0     0     0     0     0     0     0
7        0     0     0     0    50     0     0     0     0     0     0     0
8        0     0     0     0     0     0     0     0     0     0     0     0
9        0     0     0     0     0     0     0     0     0     0     0     0
10       0     0     0     0     0     0     0     0     0     0     0     0
                                                                                
Last Command: dspsloterrs


bpx1           TN    Cisco           BPX 8620  9.3.51    Mar. 18 2005 16:44 GMT 

BCC3 7          Status: Clear - Slot OK                 Clrd: 02/16/05 23:21:36
Type                 Count ETS   Status    Type              Count ETS   Status
Stby PRBS Errs        0     0          
Rx Invld Prt Errs     0     0          
Poll Bus A Parity     0     0          
Poll Bus B Parity     0     0          
Bad Grant Errs       50     0          
Tx BIP-16 Errs        0     0          
Rx BIP-16 Errs        0     0          
SIU Phase Errs        0     0          
Bfrm. Par. Errs       0     0          
Rx FIFO Sync Errs     0     0          
Poll Clk Errs         0     0          
CK 192 Errs           0     0

Last Command: dspsloterrs 7

What do they mean?

A Bad Grant error indicates that a BFrame was discarded because the transmitting card did not get a chance to send the BFrame to its destination, because it did not get a grant. As Bad Grant errors can be logged at a maximum rate of ten per second, the count is of intervals with errors, and not of the number of BFrames discarded. Since the polling algorithm is not supposed to allow this to happen, this error is an indication of a fundamental problem that must be addressed.

What should I do to make them go away?

If Bad Grant errors are seen in conjunction with Poll Parity errors or with Response Parity errors, then the Bad Grants are just a symptom of these errors. Complete the steps detailed in this document in order to resolve the problem.

If Bad Grants are seen with Invalid Address errors (in the arbstats command output), suspect a configuration problem on a card (probably in the slot indicated in the arbstats src field). You need to investigate further in order to determine whether this was due to hardware, firmware, or software. If Bad Grants are seen on a single card without any other errors, the card is probably bad, particularly if the errors increment at the maximum rate of 100 / 10 seconds.

Related Information

Updated: Dec 06, 2006
Document ID: 10812