Description

The article explains when Framing errors are being observed on the physical interfaces of peer device when traffic is sent from ACX RIO bases platform.

Below errors was being reported on the MX box .

 Physical interface: ae1
  Input errors:
   Errors: 124277, Drops: 0, Framing errors: 124277, Runts: 0, Giants: 0, Policed discards: 0, Resource errors: 0
 Output errors:
   Carrier transitions: 163, Errors: 6, Drops: 0, MTU errors: 0, Resource errors: 0
 
 Physical interface: ae1
 Input errors:
   Errors: 126355, Drops: 0, Framing errors: 126355, Runts: 0, Giants: 0, Policed discards: 0, Resource errors: 0
 Output errors:
   Carrier transitions: 15, Errors: 0, Drops: 0, MTU errors: 0, Resource errors: 0

Symptoms

On MX device which was the peer it was reported that there was continuous increase of framing errors on the physical ports connected on the directly connected interface to the ACX when packets were sent via tester from ACX towards the MX. Initially it was thought the issue is with interfaces on the MX and necessary troubleshooting were performed like cleaning optics , changing FPC cards , bypassing patch panels but errors were still incrementing on the MX .

When checked further on the ACX device it was observed that the framing errors were seen on the MX when ACX was sending corrupted packets on L1 towards the MX with values incrementing in the TX underflow . To check we need to login into the shell of ACX .  

1. Check for the BCM vale of the Port first as highlighted . 
Physical Interface: et-0/1/1    Index: 184
 BRCM Unit: 0    Port: 53        gport: 134219829(0x8000835)

2.Check show c full command output by login into the shell and check if we observe the TUFL . 

% cprod -A fpc0 -c 'set bc bc "show c full"' | egrep "ce53"
TPKT.ce53               :       285,729,602,803          +3,412,842          44,609/s
TUCA.ce53               :       285,455,979,599          +3,408,293          44,588/s
TMCA.ce53               :           254,046,261              +4,122              18/s
TBCA.ce53               :            19,576,943                +427               3/s
TVLN.ce53               :       285,604,533,508          +3,412,141          44,601/s
TDVLN.ce53              :           412,905,920              +4,683              17/s
TRPKT.ce53              :                 5,297                  +1
TUFL.ce53               :               125,540                  +1
TBYT.ce53               :   163,330,435,045,878      +2,345,269,923      31
 

Solution

On ACX devices with RIO based platform sending larger packet of size 1500 bytes & above can lead to Framing/CRC errors being reported on the peer device causing impact on the traffic . Due to transmit underflow , TX MAC starvation can lead to corrupted packets being sent towards the peer leading to Framing/CRC errors. 

The only fix is to upgrade the box to 21 or higher codes . 

Modification History

New version.