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

[Xuxiaohu <[e-mail]>]

> -----邮件原件-----
> 发件人: mpls [mailto:[e-mail]] 代表 Gregory Mirsky
> 发送时间: 2014年1月11日 2:24
> 收件人: Eggert, Lars; Joel Halpern
> 抄送: [e-mail]; IETF
> 主题: Re: [mpls] Last Call: <draft-ietf-mpls-in-udp-04.txt> (Encapsulating MPLS
> in UDP) to Proposed Standard
> 
> Hi Lars,
> I think that " The whole point of running MPLS is to create networks in which
> paths are provisionable, so this is usually not an issue." is only partially correct.
> LDP-based MPLS network is not provisionable and LSPs follow IP best route
> selection. Explicit signaling of LSP is achievable in (G)MPLS by using RSVP(-TE)
> signaling.

+1. With the replacement of a LDP-based LSP tunnel by an IP-based tunnel (e.g., MPLS-in-GRE, MPLS-in-IP or MPLS-in-UDP), the path that the traffic travels through is not changed at all.

Best regards,
Xiaohu

> 	Regards,
> 		Greg
> 
> -----Original Message-----
> From: mpls [mailto:[e-mail]] On Behalf Of Eggert, Lars
> Sent: Friday, January 10, 2014 8:10 AM
> To: Joel Halpern
> Cc: [e-mail]; IETF
> Subject: Re: [mpls] Last Call: <draft-ietf-mpls-in-udp-04.txt> (Encapsulating
> MPLS in UDP) to Proposed Standard
> 
> Hi,
> 
> On 2014-1-10, at 16:36, Joel M. Halpern <[e-mail]> wrote:
> > Maybe I am completely missing things, but this looks wrong.
> > If the MPLS LSP is carrying fixed rate pseudo-wires, adding congestion
> > control will make it more likely that the service won't work.  Is that
> > really the goal?
> >
> > We do not perform congestion control on MPLS LSPs.
> > Assuming that a UDP tunnel is carrying just MPLS and was established
> > just for MPLS, why would we expect it to behave differently than an
> > MPLS LSP running over the exact same path, carrying the exact same traffic?
> 
> we've been rehashing this discussion several times over the years, e.g., for PWE,
> AMT, etc. In order to carry fixed-rate or otherwise non-congestion-controlled
> traffic over unprovisioned general Internet paths, there needs to be some sort of
> basic congestion control mechanism, like a circuit breaker.
> 
> The whole point of running MPLS is to create networks in which paths are
> provisionable, so this is usually not an issue. But if you start sticking MPLS inside
> of UDP, those packets can go anywhere on the net, so you need mechanisms to
> control the rate of that traffic if it causes congestion, or at the very least you
> need to be able to stop the traffic if it creates severe congestion.
> 
> Lars
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