Isn't this something that could be done entirely at the sub-IP layer for link technologies where this is an issue? I'd argue that all multicast in 802.11 is badly broken, and should be fixed at that layer (multicast can be more than 50x slower than unicast, and packet loss can approach 80% while unicast is working fine... this is not good).
That said, perhaps there is call for doing multicast fan-out at the IP layer as well, for cases where the underlying link has 802.11-like multicast characteristics that cannot be fixed for whatever reason. Perhaps the IETF should even suggest that IPv6 over 802.11 should switch to this proposal, as it would improve performance dramatically while the 802.11 layer remains unfixed; there will be legacy APs around for a very long time. On Fri, Mar 29, 2013 at 2:21 PM, Mark Smith <[email protected]>wrote: > Hi, > > The following is inspired by some work I did in around 2010/2011 on a > multicast TV service, where residential customers with Wifi networks > suffered from performance problems, and had to be advised to buy ethernet > over power devices if they couldn't run wired ethernet to the STB attached > to their TV. > > I've done some experiments on my home wifi network, using VLC, and > switching between multicast and unicast IPv6 to test the concept. The wifi > performance issues disappear when the video is delivered via unicast UDP. > (If people want to play with VLC and IPv6 multicast, email me off-list, as > there are a few issues e.g. the GUI doesn't accept some of the IPv6 > multicast parameters that the command line does). > > I think there is a possibility the technique could also be applied to > IGMPv3/ARP, although it depends on whether ARP has been implemented in a > similar manner to IPv6 ND (e.g. an ARP equivalent to NUD). My understanding > is that Linux has implemented ARP this way. I'll do some more research to > verify this. > > I though I'd post it to see if there is merit in the idea and it is worth > spending more of my time on. I looked for a IETF group more suitable to > this, but didn't seem to be able to find one. If there is one, please let > me know. > > Review and comments most appreciated. > > Thanks very much, > Mark. > > > ----- Forwarded Message ----- > > From: "[email protected]" <[email protected]> > > To: [email protected] > > Cc: > > Sent: Friday, 29 March 2013 1:45 PM > > Subject: New Version Notification for > draft-smith-mldv2-link-unicast-00.txt > > > > > > A new version of I-D, draft-smith-mldv2-link-unicast-00.txt > > has been successfully submitted by Mark Smith and posted to the > > IETF repository. > > > > Filename: draft-smith-mldv2-link-unicast > > Revision: 00 > > Title: MLDv2 Procedures for Link-Layer Unicast Delivery of > Multicast > > IPv6 > > Creation date: 2013-03-29 > > Group: Individual Submission > > Number of pages: 7 > > URL: > > > http://www.ietf.org/internet-drafts/draft-smith-mldv2-link-unicast-00.txt > > Status: > http://datatracker.ietf.org/doc/draft-smith-mldv2-link-unicast > > Htmlized: > http://tools.ietf.org/html/draft-smith-mldv2-link-unicast-00 > > > > > > Abstract: > > Some multi-access link-layer technologies typically not provide good > > IPv6 multicast performance, using link-layer multicasts, when the > > volume of multicast traffic is significant. It would be possible to > > replicate and then link-layer unicast multicast IPv6 traffic to > > interested listeners to overcome these link-layer performance > > limitations. This memo describes MLDv2 and IPv6 neighbor discovery > > procedures to support link-layer unicast delivery of multicast IPv6 > > traffic. > > > > > > > > > > > > > The IETF Secretariat > > > -------------------------------------------------------------------- > IETF IPv6 working group mailing list > [email protected] > Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 > -------------------------------------------------------------------- >
-------------------------------------------------------------------- IETF IPv6 working group mailing list [email protected] Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
