In message <CAGnRvuqcwFjE6NZ_tOnQEBN8RG8wUFeSsQSqsETh=acpw_v...@mail.gmail.com> Henning Rogge writes: > Sorry, > > too much working on the implementation side of NHDP/OLSRv2 in the last > years... should have thought a bit more about the reply before sending > it. > > Yes, you are correct that RFC6130 does not contain the description of > the link metric... it only contains a rough EWMA based "link quality" > hysteresis that switches on and of links. I don't even think the > algorithm defined in the RFC is really useful (but its easy to plug in > a different one because the Link Quality calculation and decision is > just local). > > I was thinking about the Link Metric NHDP extension defined in RFC7181 > (which can easily be used without using the OLSRv2 routing), which is > based on "Incoming/Outgoing Link Metric" values. > > (in my implementation I put the whole Link Metric and MPR code into > NHDP to make them usable without OLSRv2) > > Henning Rogge
The basis for the metric in RFC 7181 is out of scope. So what did you use? Also I'm not sure what you meant by the "MPR code". Did you leave in the LINK_METRIC TLV and leave out the rest of RFC 7181? So my point still stands that there is nothing like LQM is anything over WiFi (more correctly 802.11). Curtis > On Tue, Mar 3, 2015 at 12:28 AM, Curtis Villamizar > <[email protected]> wrote: > > Henning, > > > > You cut the following off the top of your reply. > > > >> > The Neighborhood Discovery Protocol (RFC 6130) has a similar > >> > mechanism... each node collects local link quality information and > >> > then shares them from time to time with all neighbors, which means > >> > everyone knows about both directions of a link. > >> > > >> > Henning Rogge > >> > >> > >> RFC 6130 uses probes (hello message success rate). > > > > Cutting this off makes a big difference. See below. > > > > In message > > <CAGnRvup-F4_A1-sHkh3EWRgrX=iuthbdmjzz+xk_g+7bm+e...@mail.gmail.com> > > Henning Rogge writes: > >> > >> On Sun, Mar 1, 2015 at 11:14 PM, Curtis Villamizar > >> <[email protected]> wrote: > >> > RFC 6130 uses probes (hello message success rate). > >> > >> No, it does not... at least not for calculating the link metric. > > > > The discussion was the quality measurement. The quality measurement > > uses hello message success rate. See section 14 in RFC 6130. > > > > The discussion was not link metrics. You chopped the prior discussion > > when quoting the one sentence above. Below I describe the why RFC > > 6130 Link Quality is nothing like LQM. > > > >> > For example: If an AP sends 100 packets a second to a neightbor and 5 > >> > drop it would be better to send one LQM packet and know that loss is > >> > 5% rather than have to send 100 hello packets in addition to the 100 > >> > data packets to reliably know that loss is 5%. (In MPLS it could be a > >> > billion packets between LM packets). > >> > > >> > LQM does not rely on a count of probe packet success. Please reread > >> > what I sent earlier or read about PPP LQM or MPLS-TP LM OAM. > >> > > >> > Please compare RFC 6130 section 14.2 (Basic Principles of Link > >> > Quality) > >> > >> "Link quality" and "Link metric" are two different kind of things for > >> NHDP/OLSRv2. > >> > >> Link quality is used for a hysteresis mechanism that can make a link > >> symmetric/asymmetric. > >> > >> Link metric (as defined in RFC 7181) is used for path selection. > >> > >> > with RFC 1989 and RFC 6375. In RFC 6375 look at Section 2.2 > >> > (Packet Loss Measurement) and Section 3.1 (Loss Measurement Message > >> > Format). RFC 6130 has no comparable mechanism. > >> > >> RFC6130 (NHDP) and RFC 7181 (OLSRv2) define the incoming link METRIC > >> calculation as an external process. It can be anything, as long as it > >> gives you a dimensional link cost in the right range. > >> > >> I admit the splitup between RFC6130 and RFC7181 is a bit confusing... > >> > >> Henning Rogge > > > > I know the difference between link quality and link metric. > > > > You just jumped from ND to OLSRv2 for MANET. RFC 7181 does not > > preclude using a LQM-like mechanism, but neither RFC 6130 or RFC 7181 > > define such a mechanism. > > > > The discussion was regarding doing something like LQM and three > > messages ago you stated that RFC 6130 already had something like LQM. > > Neither RFC 6130 or RFC 7181 define a mechanism anything like LQM. > > > > Curtis _______________________________________________ homenet mailing list [email protected] https://www.ietf.org/mailman/listinfo/homenet
