We have been hoping to find use cases for the babel protocol's rtt metric, which builds on ideas from ntp, and is primarily used today in overlay networks: https://datatracker.ietf.org/doc/draft-ietf-babel-rtt-extension/
On Wed, Oct 18, 2023 at 7:17 AM Jason R. Rokeach via NANOG <[email protected]> wrote: > > Hi Adam, > This sounds like a use case for MPLS-TE with TWAMP-Light. TWAMP-Light handles > the latency concern and can encode your measured latency in IS-IS. Juniper > docs: > https://www.juniper.net/documentation/us/en/software/junos/is-is/topics/topic-map/enable-link-delay-advertise-in-is-is.html. > The configuration in steps 5 and 7 is all thats required (from a config > standpoint) to get the data into IS-IS. > You then, when building an RSVP LSP, would specify a constraint for the > latency. Alternatively you can route by latency on its own by setting the > metric to latency, but as you've alluded to, this can be pretty dangerous in > environments with mixed bandwidth availability. > > The other option afforded for the second point on traffic balance is to use > auto-bandwidth > (https://www.juniper.net/documentation/us/en/software/junos/mpls/topics/topic-map/basic-lsp-configurtion.html#id-configuring-automatic-bandwidth-allocation-for-lsps > - see also > https://archive.nanog.org/sites/default/files/tues.general.steenbergen.autobandwidth.30.pdf). > > Other vendors support this as well. > SR supports the use of TWAMP-Light as well if you prefer that over RSVP, but > it doesn't support auto-bandwidth. > > _______________________ > Jason R. Rokeach > m: 603.969.5549 > e: [email protected] > tg: jasonrokeach > > Sent with ProtonMail secure email. Get my PGP Public Key. > > ------- Original Message ------- > On Wednesday, October 18th, 2023 at 9:13 AM, Adam Thompson - athompson at > merlin.mb.ca <[email protected]> wrote: > > Using a mix of Juniper hardware... > > Network provides VPLS to customer, over MPLS (obviously) in a > dual-redundant-ring radio topology. Each site is connected to one or more > neighbors, generally with two radios, in two different bands, to *each* > neighbor. So an ordinary node might have 4 radios, 2 pointing in each > direction. > > Every single radio link has different bandwidth, different latency, and > different interference characteristics. > > These radio links do run at 100% capacity at least some of the time. > > It's possible to set each link's relative cost in OSPF or IS-IS, of course, > but I haven't found a way to make the router react to latency changes on one > link or the other. (Right now, I think costs are set equal so traffic will > use both links.) This means interference in one band invisibly diminishes > the Ethernet bandwidth available and silently increases the latency on that > link, sometimes dramatically. This seems to do interestingly unpleasant > things to the client's flows. > > It's generally true that one band will be much more severely affected than > the other, in any interference event. Before anyone asks, I'm told the > network is a mixture of licensed and unlicensed bands, that's not changing > anytime soon. > > In a perfect world, I'd like the routers to dynamically adjust traffic > balance, but even just temporarily halting use of the impaired link would be > helpful (or so I believe right now, at least). > > Is this a pipe dream? I'm not seeing anything in JunOS that could accomplish > this... I'm not even sure if a mesh protocol could handle dual active links > like this? > > Ideas, comments, etc. all appreciated. > > Also, I'm not the direct operator of use network. I'm involved, but mostly > just trying to help them find better solutions. Nor am I an MPLS expert, as > is obvious here. > > Thanks, > -Adam > > Adam Thompson > > Consultant, Infrastructure Services > > MERLIN > > 100 - 135 Innovation Drive > > Winnipeg, MB R3T 6A8 > > (204) 977-6824 or 1-800-430-6404 (MB only) > > https://www.merlin.mb.ca > > Chat with me on Teams > > -- Oct 30: https://netdevconf.info/0x17/news/the-maestro-and-the-music-bof.html Dave Täht CSO, LibreQos
