> -----邮件原件----- > 发件人: WashamFan [mailto:[email protected]] > 发送时间: 2010年1月21日 17:31 > 收件人: Rémi Després > 抄送: Xu Xiaohu; [email protected] > 主题: Re: [Softwires] routing loop issue//re: Please review 6rd > > Hi, > > If 6rd-A and 6rd-B belong to the same 6rd domain, I don't see the routing loops.
Yes, in case that the two 6rd BR use the same 6rd prefix which is almost Provider-Independent IPv6 address. However, if the two BRs use different 6rd prefixes, that is to say, each BR was allocated a PA address for 6rd prefix from its own upstream IPv6 ISP, there is a possibility of routing loop. Xiaohu > ----- Original Message ----- > From: Rémi Després <[email protected]> > Date: Thursday, January 21, 2010 4:04 pm > Subject: Re: [Softwires] routing loop issue//re: Please review 6rd > To: Xu Xiaohu <[email protected]> > Cc: [email protected] > > > > Le 21 janv. 2010 à 08:42, Xu Xiaohu a écrit : > > > > > > > > > > +------------------------+ > > > | | > > > | | > > > | IPv6 Internet | > > > | | > > > +------+----------+------+ > > > | | > > > | | > > > +--+--+ +--+--+ > > > +---+6rd-A+-----+6rd-B+--+ > > > | +-----+ +-----+ | > > > | | > > > | IPv4 ISP | > > > | +-------+ | > > > +-------+ CPE-1 +--------+ > > > +---+---+ > > > | > > > +-----+-----+ > > > | | > > > | IPv6 Site | > > > +-----------+ > > > > > > In the above scenario, two 6rd BRs are configured with the same > > address for > > > anycast service. Assuming the nearest 6rd BR for the CPE is 6rd-A, > > all IPv6 > > > packets from the IPv6 site and destined to the IPv6 internet will be > > > tunneled towards 6rd-A by the CPE. Once 6rd-A lost connections to > > the IPv6 > > > Internet, some failover mechanism should be used to direct these packets > > > towards 6rd-B. > > > > > One possible solution is: 6rd-A withdraws the route to the > > > IPv6 Internet, which was advertised in IPv4 ISP network previously, > > as soon > > > as its connection to the IPv6 Internet is lost. > > > > This is in my understanding the right solution, precisely because > > protection against routing loops can be achieved by preventing tunnels > > between BRs. > > > > > > > Another solution is: > > > establish a softwire tunnel between the two 6rd BRs for failover > > route. With > > > the latter solution, some normal packets tunneled in the softwire during > > > failover will be filtered mistakenly. > > > > That's why the other solution should be preferred. > > > > RD > > > > _______________________________________________ > > Softwires mailing list > > [email protected] > > https://www.ietf.org/mailman/listinfo/softwires > > _______________________________________________ Softwires mailing list [email protected] https://www.ietf.org/mailman/listinfo/softwires
