From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Frederic Sowa Subject: Re: question on ipv6 support for duplicate nexthops Date: Fri, 27 Jun 2014 09:15:27 +0200 Message-ID: <1403853327.7028.7.camel@localhost> References: <53AB41B3.1020201@cumulusnetworks.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: netdev , Daniel Walton To: Roopa Prabhu Return-path: Received: from out1-smtp.messagingengine.com ([66.111.4.25]:40555 "EHLO out1-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751598AbaF0HPb (ORCPT ); Fri, 27 Jun 2014 03:15:31 -0400 Received: from compute5.internal (compute5.nyi.mail.srv.osa [10.202.2.45]) by gateway1.nyi.mail.srv.osa (Postfix) with ESMTP id 15EE321DFA for ; Fri, 27 Jun 2014 03:15:29 -0400 (EDT) In-Reply-To: <53AB41B3.1020201@cumulusnetworks.com> Sender: netdev-owner@vger.kernel.org List-ID: On Mi, 2014-06-25 at 14:40 -0700, Roopa Prabhu wrote: > ipv4 allows duplicate nexthops. Multiple instances of same > nexthops maybe used to give higher weights to some nexthops > (though the "weight" attribute can be used for the same purpose). > > ipv6 does not seem to support duplicate nexthops. > > Example: The below ipv6 route is rejected by the kernel > #ip -6 route add 2001:10:1:3::/64 nexthop via 2001:10:1:2::99 nexthop > via 2001:10:1:2::99 > > The below patch points to the code that is preventing the addition of > duplicate nexthops. > > I am not sure yet if there are other side effects to the patch below. > If there is interest in making ipv6 consistent with ipv4 for duplicate > nexthop handling, i can submit a patch. ECMP routes are normal routing entries in the fib, just hold together via an internal list and thus behave differently than IPv4 ECMP routes. I don't see that just removing the check for duplicate entries will make that work correctly. Also you remove some pretty important expire update code. Bye, Hannes > diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c > index cb4459b..afecc87 100644 > --- a/net/ipv6/ip6_fib.c > +++ b/net/ipv6/ip6_fib.c > @@ -698,20 +698,6 @@ static int fib6_add_rt2node(struct fib6_node *fn, > struct rt6_info *rt, > break; > } > > - if (iter->dst.dev == rt->dst.dev && > - iter->rt6i_idev == rt->rt6i_idev && > - ipv6_addr_equal(&iter->rt6i_gateway, > - &rt->rt6i_gateway)) { > - if (rt->rt6i_nsiblings) > - rt->rt6i_nsiblings = 0; > - if (!(iter->rt6i_flags & RTF_EXPIRES)) > - return -EEXIST; > - if (!(rt->rt6i_flags & RTF_EXPIRES)) > - rt6_clean_expires(iter); > - else > - rt6_set_expires(iter, > rt->dst.expires); > - return -EEXIST; > - } > /* If we have the same destination and the same > metric, > * but not the same gateway, then the route we > try to > * add is sibling to this route, increment our > counter > > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html