Description

This article explains why major​ alarm ​CB* 1 ESW PFE port failure occurs. 

*CB - Switch Control Board (SCB)
Note: In MX Platforms, CB resides within RE (Routing-Engine). So replacement of CB means replacement of RE.  

Symptoms

The following major alarm is seen: 

admin@> show chassis alarms
1 alarm currently active
Alarm time               Class  Description
2018-09-24 11:37:59 AEST Major  CB 1 ESW PFE Port Fail

Solution

This may be caused by ether-switch link down between CB and FPC, but in most cases, it may be due to hardware failure of either the CB or FPC. 

The following steps help in isolating the issue to be on CB or FPC. 

​Collect below output from both routing-engines and identify if 'Link is down' from any one of the REs. 

show chassis environment cb 1
show chassis environment cb 0
show chassis ethernet-switch errors
show chassis ethernet-switch statistics
show chassis ethernet-switch | no-more

Login into another RE:

request routing-engine login other-routing-engine 
show chassis ethernet-switch errors
show chassis ethernet-switch statistics
show chassis ethernet-switch | no-more

  1. Analyze above  show command outputs and identify which link shows 'down' from one RE and 'good' from another RE. That link needs to be fixed using step 2 mentioned below. 

    Check which ethernet link is down. It should say the following:

    Link is good on GE port 9 connected to device: FPC9

    If it says this:

    Link is down on GE port 9 connected to device: FPC9

    This means the ether-switch link between CB1 and  FPC9 is down. Here is the sample output from the lab device:  
root@RE0> show chassis ethernet-switch | no-more

Displaying summary for switch 0
Link is good on GE port 0 connected to device: FPC0
<> 
Link is good on GE port 9 connected to device: FPC9
  Speed is 1000Mb
  Duplex is full
  Autonegotiate is Enabled
  Flow Control TX is Disabled
  Flow Control RX is Disabled
 
root@RE0> request routing-engine login other-routing-engine
Last login: Thu Apr  4 01:25:53 from re1

root@RE1> show chassis ethernet-switch | no-more
 
Displaying summary for switch 0
Link is good on GE port 0 connected to device: FPC0
<> 
Link is down on GE port 9 connected to device: FPC9  <-- LINK DOWN
 
Link is good on GE port 10 connected to device: FPC10
  Speed is 1000Mb
  Duplex is full
  Autonegotiate is Enabled
  Flow Control TX is Disabled
  Flow Control RX is Disabled

2. Now that the issue has been identified between RE1 and FPC9, take the following steps during a Maintenance Window to isolate and resolve the issue. 

  1. Use hidden command 'test chassis ethernet-switch fpc-port enable 9' to bring the link up.      <-- 9 - indicates FPC9

  2. If step 1 does not clear the issue, re-seat CB in the same window.

  3. If step 2 does not clear the issue, re-seat FPC in the same window.

  4. If step 3 does not clear the issue, try to replace CB.

  5. If step 4 does not clear the issue, try to replace FPC.

If the the steps above do not resolve the issue, contact your technical support representative to investigate the issue further.