Junos
Junos

policer problem

10.22.08   |  
‎10-22-2008 12:59 PM

If I add a policer to a customer vlan

 

policer 6-meg-policer {
    if-exceeding {
        bandwidth-limit 6m;
        burst-size-limit 30k;

 

I only get max 1.5m of speed. I use the same policer on a diferent unit/vlan on the same interface with no problems. 

 

Any ideas? 

I seen bug
NUMBER      300004 It is for the Jseries 

I am running m10i 9.1R2.10

 

4 REPLIES
Junos

Re: policer problem

10.23.08   |  
‎10-23-2008 01:52 AM

Hi Sinergy,

 

How bursty is the traffic that you're seeing on this logical interface?  You've got a burst of 30k, which is a decent sized burst for regular traffic (around 20xMTU if you're using 1500 Byte MTU).  However, if you're using a traffic generator, for example, with a 1GE interface and telling it to generate 6Mbps, many devices will generate 1Gbps for 6/1000 of a period and nothing for the other 994/1000s then 1Gbps for 6/1000s and nothing for the other 994/1000s.  Basically, many traffic generators will default to producing an average of the value you request but in a massively bursty fashion.

 

This will cause terrible problems with a policer (or for devices with small buffers) because you're constantly filling the buffer and tail dropping.

 

The PR to which you refer is specifically on the J series.  The fix for this should be in 9.1R3.

 

Rgds,

 

Guy 

Junos

Re: policer problem

01.21.11   |  
‎01-21-2011 06:26 AM

I have the same problem.

Does it mean what I should use bigger burst-size-limit  value ? For example? for bandwidth-limit = 10m .

Junos

Re: policer problem

01.21.11   |  
‎01-21-2011 06:49 AM

Do I understand correctly that in order to prevent tail dropping for 10m policer I need set burst-size-limit = ((10/1000[sec])*1G[bps]) / 8 to get buffer size in bytes ?

Junos

Re: policer problem

01.23.11   |  
‎01-23-2011 09:42 PM

 


Sinergy wrote:

If I add a policer to a customer vlan

 

policer 6-meg-policer {
    if-exceeding {
        bandwidth-limit 6m;
        burst-size-limit 30k;

 

I only get max 1.5m of speed. I use the same policer on a diferent unit/vlan on the same interface with no problems. 

 

Any ideas? 

I seen bug
NUMBER      300004 It is for the Jseries 

I am running m10i 9.1R2.10

 


Is this policer only applied to a single vlan?  If it isn't, the policer's work as a sum with 1 bucket.  Which if you have it applied twice, those 2 vlans will share 6Mb.