In message <CAHF4apPfmB5gveLAULhbGaHQTf=gwteo01uushoc3rmwp0s...@mail.gmail.com> Balaji venkat Venkataswami writes: > As you might recall one such research paper on GreenTE by Beichuan > Zhang rang a lot of bells in the IETF by collecting the ANRP prize. So > please dont misstate facts as you might know them and shove your ideas > of how networks are built down our throats.
That was a research paper published in IEEE International Conference on Network Protocols (ICNP). Power savings potential (a computation, not a measurement) were as high as 20-40%. That is good but ... Line cards considered were old OC3, OC48, and one port OC192 cards. The paper ignores the reality that shutting off one port on a multiport card makes little difference, certainly far less than a reduction of 1/N. The power consumption of transport was not included. Impact on fault restoration was not considered. Lots of other flaws, but still good work and a potential 20-40% is nice, even if factoring in reality might get only half that or less. The point though is that a 1 port OC192 at 174 watts (10 Gb/s) is no match for a 500 Gb/s card at roughly 650 watts. That is more than 40%. It is more than a decimal order of magnitude greater. It is not comparing apples to oranges, one is an IP/MPLS router with full routing tables and short haul interfaces, the other does OTN switching drives either short haul or long haul transport interfaces, and could do IP/MPLS, but with only IGP routes and MPLS LSPs at that power figure. So maybe the way the network is built needs to change. Anyway, if *I* were to continue this discussion, then *I* should get off the IETF lists and go write an academic paper. [Or better yet, work for a service provider or equipment vendor and work toward building better equipment and networks.] The point is that efficiency has gone up by orders of magnitude as we went from OC3 to OC12 to OC48 to OC192 (circa 1995-2000) and then multiport OC192 and OC768 and 10GbE (circa 2005-2010) to 100GbE and ODU4 (somewhat recent) to multiport 100GbE and ODU4 (even more recent). Power per bit drops about one to two decimal order of magnitude per decade and for any given a specific snapshot in the technology timeline, there are means to reduce power that get far more than the 20-40% that GreenTE potentially offers. Of course a new generation of equipment means CapEx and GreenTE is perceived as just routing and therefore free, so therefore the interest. Another point is that no one ever tried this on a real network. With RSVP-TE no protocol changes would be necessary, just offline computation, a configured preferred explicit-path, and some interface shutdowns. I don't know that anyone has even measured the reduction in power of an idled or administratively shut down interface or line card. There was nothing in the paper on this. > > If you want to try to advance a research paper with your theories on > > power reduction, please choose an appropriate venue such as a refereed > > technical journal. I repeat my main point. [And hope to be among the reviewers] Also IMHO GreenTE as described by Zhang is more likely to be feasible with MPLS and RSVP-TE than with OSPF or BGP or PIM, etc. But then, the feasibility and potential benefits of GreenTE using IGP, BGP, and PIM is what your academic paper can try to defend. Thank you, Curtis _______________________________________________ rtgwg mailing list [email protected] https://www.ietf.org/mailman/listinfo/rtgwg
