[j-nsp] What exactly causes inconsistent RTT seen using ping utility in Junos?

[Raphael Mazelier]

> 
> For those of you interested in all the details around how the transit as
> well as host-inbound and host-outbound traffic is handled on juniper MX3D
> Trio architecture I'd recommend reading the following FREE book in its
> entirety.
> https://www.juniper.net/us/en/training/jnbooks/day-one/networking-technologi
> es-series/packet-walkthrough-mx-series/
> It's an excellent book that will answer, among others, all your questions
> around where the ICMP might be delayed in the system and where and how it is
> handled.
> 
> I'd say it's a must read for all NetEng/Arch working with Juniper MX.
> 
> 


This is sure a very good resource (from the excellent David Roy). I've 
already read it in the past and forget most of it. So for icmp we are in 
the case of an "exception packet" that are "punted" to the RE. But the 
document did not detail what really happen in the RE. It mention that 
theses packets transit by gigabit ethernet interfaces in the TPP 
proprietary protocol, but nothing after. What daemon is in charge of 
handling TPP flow on the RE side ? rpd ? for icmp is at the end the 
packet go through the freebsd kernel (seems logic but). And what cause 
latency in response ?


--
Raphael Mazelier