Description

For linecards (MPCs) or service cards (MS-MPCs) that require enhanced IP, if the network-service is not enabled properly, traffic forwarding issues can be seen.This issue may cause Broadcast/Unknown Unicast/Multicast (BUM) traffic drops within the PFE (Packet Forwarding Engine).

Symptoms

When the command "set chassis network-service enhanced-ip" is configured and both REs are not rebooted at the same time, the "enhanced-ip" may not be properly programmed in the PFE and different network-service modes may be in the RE and FPCs:

  • RE side: 

user@router> show chassis network-services
Network Services Mode: Enhanced-IP

  • FPC side: 

user@router> start shell
% cprod -A -c 'show jnh vc mc state'

GLOBAL VC MULTICAST INFO
========================
  VC Mode Enabled:          ---> NO<---
  chassis id non-0:         ---> NO<---
  VC jnh structs allocated: ---> NO<---
  VC Member ID  (0 based): 0
  VC Chassis ID (1 based): 0

  VC BSDT target: No
  static mcast mode: ICHIP INTEROP​

The static mcast mode can be one of the two following values:

  • TRINITY-ONLY for enhanced-ip
  • ICHIP INTEROP for ip

It is also important to check the network mode in the RE kernel, because it can be corrupt if the network service mode is not properly added. 

user@router> start shell
% sysctl -a | grep netsvc
net.netsvc: 2

The variable net.netsvc can be one the following values:

0 : IP
1 : ethernet
2 : enhanced IP
3 : enhanced Ethernet
4 : all IP
5 : all Ethernet
6 : enhanced mode
7 : lan

When traffic is impacted, you may see the "sw error" exception counter increase in PFE: 

user@router> show pfe statistics exceptions
...
Slot 1
LU 0
PFE State Invalid
----------------------
sw error                           DISC( 64)            10012          5896454
invalid fabric token               DISC( 75)            0          0
...

Solution

After installing the new RE and the required Junos OS software with configuration, perform a reboot.

If you encounter a mismatch in network-service mode, perform a system reboot,