On Fri, Mar 28, 2008 at 09:23:56AM -0700, Joseph Mack NA3T wrote: > On Fri, 28 Mar 2008, Julius Volz wrote: > >> Hi LVS devs, >> >> I'm currently interning at Google Zurich and we are very interested in >> porting IPVS to IPv6. Indeed, I will probably dedicate 60-70% of my >> time to that cause for the next 5 months to come. > > wonderful. Thanks > >> 1) It looks as though there is no current effort on the way to do this >> port, right? > > correct. There was a very old effort that you can find if you search a bit - I can dig up a link if you can't find it. But as far as I am aware there are no efforts at this time. >> 2) Are there any serious technical or political roadblocks to this we >> are not seeing? > > There is an effort underway to move ipvs() from the LOCAL_IN chain, where > it currently sits for historical reasons, to a better place. A better > place is either PREROUTING or FORWARD. Both hooks look OK at the moment. > It is possible that the location will be decided at run time. This work > is being done by Janusz, who is on this mailing list, but AFAIK it's not > in the kernel and hasn't had testing by selected users. You should > coordinate with him so that your codes are compatible. > > There is a problem with PMTU discovery when using LVS-Tun (described in > the HOWTO), which is currently handled (I think) by iptables and an mss > option. Part of the problem is that the Linux networking stack doesn't do > PMTU correctly. > At least be prepared for this problem. I don't know how easy it would be > to fix. > > We don't have enough people using UDP to know how LVS should handle UDP. > There are problems with UDP (described in the HOWTO). People are trying > to setup SIP on LVS. With all the ports involved in the protocol, I don't > expect it will be easy. I expect the only solution will be a module on > the director (like the ftp helper) that understands the SIP protocol. It > seems that multiport protocols are going to become more common as coders > try to get through ISPs who think it's their business to throttle the > internet. > > ipvs has an uneasy relationship with netfilter. ipvs bypasses netfilter > for speed. However in doing so, iptables no longer works as users would > reasonably expect (at least for LVS-NAT). With cpus getting faster, > relative to networks (I think that's true), it may not hurt if ipvs is a > little slower, for more compatibility with netfilter. However the speed > of ipvs is a well regarded feature. *BSD has loadbalancing but it's slow > compared to ipvs, so we wouldn't want to drop too much speed. [ Joe, I'm not sure that the LOCAL_IN stuff is really related specifically to IPv6. But you do remind me that those patches need to be revisited. ] About six months ago I spoke very briefly with Dave Miller (who is ultimately who is going to decide if the code goes in or not) and he had no objections. >> 3) Currently, IPVS lives under .../net/ipv4/ipvs in the kernel, but >> much of the code is not IPv4-specific. > > I expect this is all historical, from when ipvs was based on > masquerading code, rather than netfilter. > >> Any ideas on how to best refactor that common code to make it usable >> for both IPv4 or IPv6? > > If you write it and are happy with it, we'll take your scheme :-). Horms > has been doing all the work on LVS for the last couple of years, knows > the code and has thought a lot about where LVS should and shouldn't go. > I'm sure he'll have ideas on what's best. Yes, I expect so to. It would be good to open up a discussion with Dave Miller and the other netdev people about any refactoring that you think is needed. They should be able to advise on what should go where. >> 4) How could this work be best split up into manageable chunks that >> could either be worked on serially or in parallel (by multiple >> developers)? > > There hasn't been much developement on ipvs recently. The original > developer Wensong hasn't been active for a while and Horms took over. > Horms is the one who submits the new code to the kernel. But Horms has > been busy doing other things and in the meantime ipvs is not getting a > lot of attention. So you'll be it if you take on the ipv6 job. > >> 5) Who else would be interested in parts of this effort or just in >> helping out when questions come up? > > Anyone on this list will be happy to listen to anything you have to say > :-) IPv6 is something that has been needed for a long time. I'm quite interested in it myself. But to date haven't had any luck finding time to work on it. I'm happy to help out with your effort. Though I imagine that for the most part it will be in the form of reviewing patches. >> So I've been looking at the code for a couple of days now and some >> parts I understand well, others I don't get at all, but I hope to >> change that soon ;) > > good luck. Thanks for taking on the job. To be honest, sometimes when I look at the code I get surprises too. But if you have any questions please just send them my way, CC usually gets my attention. -- Horms -- To unsubscribe from this list: send the line "unsubscribe lvs-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
