> -----邮件原件----- > 发件人: mpls [mailto:mpls-bounces@xxxxxxxx] 代表 Curtis Villamizar > 发送时间: 2014年1月15日 9:14 > 收件人: Wesley Eddy > 抄送: Scott Brim; Eggert, Lars; IETF discussion list; mpls@xxxxxxxx > 主题: Re: [mpls] Last Call: <draft-ietf-mpls-in-udp-04.txt> (Encapsulating MPLS > in UDP) to Proposed Standard > > > In message <52D5642A.7090103@xxxxxxxxxxxxxxx> > Wesley Eddy writes: > > > On 1/14/2014 11:06 AM, Eggert, Lars wrote: > > > Hi, > > > > > > On 2014-1-14, at 16:39, Scott Brim <scott.brim@xxxxxxxxx> wrote: > > >> Lars, I know we're repeating arguments from the last decade. The > > >> choice is between (1) specifying congestion control around the > > >> substrate UDP that can be turned off if it causes problems, or (2) > > >> specifying nothing at this time and adding it later if operators > > >> want it. > > >> > > >> I guess if this can be written as a SHOULD, up to the implementor's > > >> discretion, then okay. > > > > > > I don't think we can leave this up to implementors discretion. We've had > IETF consensus that Internet communication requires congestion control at least > since RFC2914. A circuit breaker mechanisms seems straightforward to > implement. > > > > > > As is, I object to this document going forward. The minor benefits of getting > some better load balancing for MPLS are far outweighed by the risks. > > > > > > (I'm also going to shut up now, and let others speak. I think I've > > > said my bit.) > > > > > > > > > I'm in basic agreement. > > > > Assuming we might all agree that there are conceivable scenarios where > > a circuit breaker mechanism would be useful, is the real issue that we > > don't all agree that it could be implemented in a way that's not > > burdensome and doesn't degrade performance unnecessarily? > > > > Or is there still fundamental disagreement about whether the scenarios > > where the circuit breaker is useful are even valid? > > > A circuit breaker (drop all traffic on sign of congestion) at the MPLS over UDP > level would be the worst thing you could specify and IMO it would guarentee > zero implementations. > > A circuit breaker might be appropriate for TDM over PW but nothing else. This > makes sense because TDM cannot change its bandwidth so the only choice is to > shut it off. TDM over PW is an application that can run over MPLS (or GRE or > L2TP). The best place to put that circuit breaker (if anywhere at all) is in TDM > over PW. I couldn't agree more with Curtis's point. Since RFC3985 has already made a detailed description of congestion considerations about PWs, it seems that the simplest way is just to add a reference to that RFC in this doc, in addition to the text I have proposed in a previous email. The advantage of this choice is: since there is only one place where the congestion control mechanism for MPLS/PW traffic is specified, it's much easier for operators and implementors to refer. In addition, once a more practical congestion control mechanism was found in the future, it only needs to update one RFC, rather than updating many RFCs. Best regards, Xiaohu > Curtis > _______________________________________________ > mpls mailing list > mpls@xxxxxxxx > https://www.ietf.org/mailman/listinfo/mpls