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

[adamv0025 at netconsultings.com]

> Raphael Mazelier
> Sent: Tuesday, April 16, 2019 3:51 PM
> 
> On 16/04/2019 15:52, Saku Ytti wrote:
> > On Tue, 16 Apr 2019 at 16:35, Vincent Bernat <bernat at luffy.cx> wrote:
> >
> >> Can you confirm that rpd is answering ICMP echo requests? I find this
> >> surprising as I would have expected the FreeBSD kernel to do that.
> >
> > You're probably right. So more likely is that LC CPU is busy doing
> > programming RPD asked it to do, instead of giving ICMP towards RE.
> >
> 
> This is interesting discussion. It was always unclear to me what are
handled
> by the freebsd kernel, rpd, or the micro junos kernel.
> 
Hi gents,

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.


adam