Ethernet Switching
Ethernet Switching

How to find what is being dropped

04.16.10   |  
‎04-16-2010 01:45 AM



Can you tell me what would be the best way to view what is being dropped?


Egress queues: 8 supported, 4 in use
  Queue counters:       Queued packets  Transmitted packets      Dropped packets
    0 BEST-EFFORT                    0              3347162                          17086
    1 PRIORITY-DAT                   0                    0                    0
    5 REAL-TIME                      0                    0                    0
    7 NETWORK-CONT                   0                   75                    0
  Active alarms  : None
  Active defects : None



Ethernet Switching

Re: How to find what is being dropped

04.17.10   |  
‎04-17-2010 12:27 AM



Do you know if your interface is overcrowded ?

The traffic exceeding the output bandwidth will be dropped randomly


There is not a simple way to find which one as it is dropped randomly


I assume you didn't configured something particular on QOS and left the default configuration (I only see 2 queues used that is the default)


You can configure a particular QOS behavior to put more priority to your important traffic and less priority to the one that is less important and route these traffics in two different queues.


In this way you will directly know what is dropped.



Ethernet Switching

Re: How to find what is being dropped

04.19.10   |  
‎04-19-2010 06:11 AM

You should open a ticket.  I have experiecned drops in the best-effort queue on WAN uplink interfaces on my EX4200 virttual chassis running JUNOS 9.3R3.4.  I have also been able to replicate the issue in a lab setting running 10.0S1.1.  JTAC was able to identify the drops as tail drops by examining the buffers on PFE (Packet Forwarding Engine) by connecting to the PFE directly in the shell. 


JTAC recommend setting up queues to further categorize traffic to isolate the culprit, but I have not done this.