Hi Ruediger, I have read your draft and presentation with interest as I am a big supporter and in some lab trials of end to end network path probing.
Few comments, observations, questions: You are essentially measuring and comparing delay across N paths traversing known network topology (I love "network tomography" name !) * First question - this will likely run on RE/RP and in some platforms path between LC and RE/RP is completely deterministic and can take 10s or 100s of ms locally in the router. So right here the proposal to compare anything may not really work - unless the spec mandates that actually timestamping is done in hardware on the receiving LC. Then CPU can process it when it has cycles. * Second question is that congestion usually has a very transient character .... You would need to be super lucky to find any congestion in normal network using test probes of any sort. If you have interfaces always congested then just the queue depth time delta may not be visible in end to end measurements. * Third - why not simply look at the queue counters at each node ? Queue depth, queue history, min, avg, max on a per interface basis offer tons of information readily available. Why would anyone need to inject loops of probe packets in known network to detect this ? And in black box unknown networks this is not going to work as you would not know the network topology in the first place. Likewise link down/up is already reflected in your syslog via BFD and IGP alarms. I really do not think you need end to end protocol to tell you that. + s/nodes L100 and L200 one one/nodes L100 and L200 on one/ :) Many thx, R. On Wed, Feb 26, 2020 at 8:55 AM <ruediger.g...@telekom.de> wrote: > Dear IPPM (and SPRING) participants, > > > > I’m solliciting interest in a new network monitoring metric which allows > to detect and locate congested interfaces. Important properties are > > - Same scalability as ICMP ping in the sense one measurement relation > required per monitored connection > - Adds detection and location of congested interfaces as compared to > ICMP ping (otherwise measured metrics are compatible with ICMP ping) > - Requires Segment Routing (which means, measurement on forwarding > layer, no other interaction with passed routers – in opposite to ICMP ping) > - Active measurement (may be deployed using a single sender&receiver > or separate sender and receiver, Segment Routing allows for both options) > > > > I’d be happy to present the draft in Vancouver.. If there’s community > interest. Please read and comment. > > > > You’ll find slides at > > > > > https://datatracker.ietf.org/meeting/105/materials/slides-105-ippm-14-draft-geib-ippm-connectivity-monitoring-00 > > > > Draft url: > > > > https://datatracker.ietf.org/doc/draft-geib-ippm-connectivity-monitoring/ > > > > Regards, > > > > Ruediger > _______________________________________________ > spring mailing list > spring@ietf.org > https://www.ietf.org/mailman/listinfo/spring >
_______________________________________________ spring mailing list spring@ietf.org https://www.ietf.org/mailman/listinfo/spring
