[mpls] 答复: Last Call: <draft-ietf-mpls-in-udp-04.txt> (Encapsulating MPLS in UDP) to Proposed Standard

[Xuxiaohu <[e-mail]>]

Hi Lars,

> -----邮件原件-----
> 发件人: Eggert, Lars [mailto:[e-mail]]
> 发送时间: 2014年1月10日 16:48
> 收件人: Xuxiaohu
> 抄送: IETF; [e-mail]
> 主题: Re: Last Call: <draft-ietf-mpls-in-udp-04.txt> (Encapsulating MPLS in UDP)
> to Proposed Standard
> 
> Hi,
> 
> that sounds good. What congestion control are you going to be specifying for
> your tunnel?

IMHO, this is a common issue with any other encapsulations for MPLS and even other applications of UDP tunnels . Of course, the following text could be added if we believe it's necessary: 

   "...applications that uses the encapsulation as specified in this
   document SHOULD monitor the packet loss rate to ensure that it is
   within acceptable parameters. Packet loss is considered acceptable
   if a TCP flow across the same network path under the same network
   conditions would achieve an average throughput, measured on a
   reasonable timescale, that is not less than that of the MPLS-in-UDP flow.
   The comparison to TCP cannot be specified exactly, but is intended as
   an "order-of-magnitude" comparison in timescale and throughput.

   In essence, this requirement states that it is
   not acceptable to deploy an application using the encapsulation
   specified in this document on the best-effort Internet, which
   consumes bandwidth arbitrarily and does not compete fairly with TCP
   within an order of magnitude. One method of determining an
   acceptable bandwidth is described in [RFC3448]. "

Best regards,
Xiaohu


> Lars
> 
> On 2014-1-10, at 4:46, Xuxiaohu <[e-mail]> wrote:
> 
> > Hi Lars,
> >
> > Thanks a lot for your comments.
> >
> > I wonder whether the following modified text for Congestion Consideration
> section is OK from your point of view:
> >
> > Since the MPLS-in-UDP encapsulation causes MPLS packets to be forwarded
> through "UDP tunnels", the congestion control guidelines for UDP tunnels as
> defined in Section 3.1.3 of [RFC5405] SHOULD be followed. Specifically, MPLS
> can carry a number of different protocols as payloads. When the payload traffic
> is IP-based and congestion-controlled, the UDP tunnel SHOULD NOT employ its
> own congestion control mechanism, because congestion losses of tunneled
> traffic will already trigger an appropriate congestion response at the original
> senders of the tunneled traffic. When the payload traffic is not known to be
> IP-based, or is known to be IP-based but not congestion-controlled, the UDP
> tunnel SHOULD employ an appropriate congestion control mechanism.
> Furthermore, because UDP tunnels are usually bulk-transfer applications as far
> as the intermediate routers are concerned, the guidelines as defined in Section
> 3.1.1 of [RFC5405] SHOULD apply.
> >
> > Best regards,
> > Xiaohu
> >
> >> -----邮件原件-----
> >> 发件人: mpls [mailto:[e-mail]] 代表 Eggert, Lars
> >> 发送时间: 2014年1月8日 18:22
> >> 收件人: IETF
> >> 抄送: [e-mail]
> >> 主题: Re: [mpls] Last Call: <draft-ietf-mpls-in-udp-04.txt>
> >> (Encapsulating MPLS in UDP) to Proposed Standard
> >>
> >> Hi,
> >>
> >> On 2014-1-2, at 16:14, The IESG <[e-mail]> wrote:
> >>> - 'Encapsulating MPLS in UDP'
> >>> <draft-ietf-mpls-in-udp-04.txt> as Proposed Standard
> >>
> >>
> >> this document needs to describe how it addresses the issues raised in
> >> BCP145 (RFC5405). It already contains some text about messages sizes
> >> and congestion considerations, which is great. Unfortunately, the
> >> text about congestion considerations is not fully in line with RFC5405.
> >>
> >> Lars