[j-nsp] Ping RTD behaviour

Gary Tate gtate@juniper.net
Wed, 20 Nov 2002 10:23:31 -0800


When you ping the router R2 you are sending packets to the Routing 
Engine.  R2 has queues from the forwarding plane (PFE) to the control 
plane (RE).  Then the reply needs to be processed by the  RE and then 
sent back to the PFE (Queued again).  The link between the RE and the 
PFE is FastEther.  This is where the extra delay is probably introduced

The server/switch is probably a faster path than the PFE-RE one.

Gary

Abdelhamid TIBERDANI wrote:
> Hi all
> 
> Can someone help understanding the following ping RTD behaviour, the RTD is
> always better beween R1 and the SERVER than between R1 and R2 (directly
> connected)
> 
> R1
> -------------------------------R2--------------------Switch-----------------
> ----SERVER
> 10.0.0.1            10.0.0.2
> 20.0.0.2
> 
> When I perform a ping test between R1 ip@10.0.0.1  to R2 ip@10.0.0.2 the
> RTD is :round-trip min/avg/max/stddev = 0.818/0.865/0.968/0.043 ms
> 
> When I perform a ping test between R1 ip@10.0.0.1  and the SERVER
> Ip@20.0.0.2 the RTD  is always better , round-trip min/avg/max/stddev =
> 0.533/0.578/0.679/0.052 ms
> 
> Regards
> Abdel
> 
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