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Date: Mon, 3 Feb 2014 17:08:38 +0100 From: Hannes Frederic Sowa <hannes@...essinduktion.org> To: Nicolas Dichtel <nicolas.dichtel@...nd.com> Cc: Sohny Thomas <sthomas@...ux.vnet.ibm.com>, netdev <netdev@...r.kernel.org>, linux-kernel@...r.kernel.org, yoshfuji@...ux-ipv6.org, davem@...emloft.net, kumuda <kumuda@...ux.vnet.ibm.com> Subject: Re: [PATCH] ipv6: default route for link local address is not added while assigning a address Hello! On Mon, Feb 03, 2014 at 04:23:00PM +0100, Nicolas Dichtel wrote: > Le 03/02/2014 08:19, Sohny Thomas a écrit : > > > >>Actually I am not so sure, there is no defined semantic of flush. I would > >>be ok with all three solutions: leave it as is, always add link-local > >>address (it does not matter if we don't have a link-local address on > It matters. This address is required. > RFC 4291 > Section 2.1: > All interfaces are required to have at least one Link-Local unicast > address (see Section 2.8 for additional required addresses). > Section 2.8: > o Its required Link-Local address for each interface. Yes, sure, it is required. But you also can manually delete the LL address and we don't guard against that. > >>that interface, as a global scoped one is just fine enough) or make flush > >>not > >>remove the link-local address (but this seems a bit too special cased for > >>me). > > > >1) In case if we leave it as it is, there is rfc 6724 rule 2 to be > >considered ( > >previously rfc 3484) > > > >Rule 2: Prefer appropriate scope. > > If Scope(SA) < Scope(SB): If Scope(SA) < Scope(D), then prefer SB and > > otherwise prefer SA. Similarly, if Scope(SB) < Scope(SA): If > > Scope(SB) < Scope(D), then prefer SA and otherwise prefer SB. > > > >Test: > > > > Destination: fe80::2(LS) > > Candidate Source Addresses: 3ffe::1(GS) or fec0::1(SS) or LLA(LS) > > Result: LLA(LS) > > Scope(LLA) < Scope(fec0::1): If Scope(LLA) < Scope(fe80::2), no, > > prefer LLA > > Scope(LLA) < Scope(3ffe::1): If Scope(LLA) < Scope(fe80::2), no, > > prefer LLA > > > > > >Now the above test fails since the route itself is not present, and the > >test > >assumes that the route gets added since the LLA is not removed during the > >test > In your scenario, the link local route has been removed manually, not by the > kernel. What is your network manager? The test scenario is outlined here: <https://bugzilla.kernel.org/show_bug.cgi?id=68511> Basically, the command in question is this one: [root@...alhost ~]# ip -6 -statistics -statistics route flush dev eth0 which removes the fe80::/64 route. > >2) having a LLA always helps in NDP i think > A link-local Address yes, it's a MUST. But having only the link local route > will > not help. Agreed, the LL address should be available, too. I currently don't know what will break if LL address is not available. I guess MLD won't work properly and thus even basic connectivity won't work with some switches. > >3) making flush not remove link-local address will be chnaging > >functionality of > >ip flush command > You can flush by specifying the prototype: > ip -6 route flush proto static So we have four possiblities now: 1) leave it as is seems still acceptable to me 2) add fe80::/64 route unconditionally if any address gets added Sohny's patch already looks good in doing so at first look. 3) add fe80::/64 route in case LL address gets added via inet6_rtm_newaddr would be ok, too. I tend towards this solution somehow by now. 4) make flush not remove the fe80::/64 address Least favourable to me. I guess this also woud need iproute change and seems most difficult to do. Any opionions? Greetings, Hannes -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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