perfSONAR User Q&A and Other Discussion

[Eli Dart <>]

Hi Roberto,

This strikes me as a situation where details are going to matter - potentially a lot.

The L2L tunnel is presumably carrying a bunch of production traffic.....I'd want to be sure that I understood the bandwidth available on that tunnel before I did any throughput testing over it. This includes several things, such as the capabilities of the hardware at both ends (interface speeds, tunnel encapsulation/decapsulation performance, CPU vs. hardware implementation for tunnel encap/decap, etc), what the background traffic characteristics look like (is there a bunch of loss-sensitive stuff running over this, what does the blast radius for mistakes look like, e.g. does all the phone and video traffic traverse it, etc), how the L2L link is integrated into the rest of your infrastructure (lots of fan-in, high-speed router vs. cheap low-speed router, etc) and so on.

One thing you might start with is a set of OWAMP boxes, one or two at each site depending on how your network is built. Then yes - test across the L2L path as well as out to SANReN from each site, and see what you can see from a latency/loss perspective. After that, decide how to proceed next.

If this sounds overly-cautious, it might be. However, tunnels are tricky. You're dealing with not only the parameters of the local links and the local hardware you're running (including several different layers just on that stuff), but also everything that the provider is doing. Because you're in a tunnel, you can't see the characteristics of the tunnel path from within the tunnel - from the perspective of tests which traverse the tunnel all you can see is that there is one hop (the tunnel) which may or may not have consistent behavior and may or may not be able to handle load or bursts or whatever.  Now, if you can engineer a perfSONAR test that runs outside the tunnel and traverses the same path as the tunnel, that could be very valuable. Then of course you'll need to figure out whether your testing competes with the tunnel in a way that causes performance problems (e.g. congestion) for the encapsulated traffic, but you'll have a way of comparing tests within the tunnel to tests outside the tunnel on the same path, which can help identify whether problems you might see exist inside or outside the tunnel. That can help with attribution.

Anyway - definitely go forward, and definitely start running tests. I would just be cautious with throughput testing at first, and I would make sure I understood all the interactions involved before I started filling pipes.

Eli

On Thu, Aug 23, 2018 at 7:57 AM Roberto Carna <> wrote:

Dear, I need your advice please:

We have two corporate networks communicated between them by a L2L
link, and connected to Internet too.

In order to start testing and using pefSONAR, do you think it's a good
idea to put one perfSONAR server in each site of our company (in a DMZ
behind both firewalls)  in order to measure the L2L link parameters,
and also connect these perfSONAR servers to a SANReN perfSONAR server
near us ???

Thanks a lot, regards !!!

--

Eli Dart, Network Engineer                          NOC: (510) 486-7600

ESnet Science Engagement Group                           (800) 333-7638

Lawrence Berkeley National Laboratory