[Irtf-rr] Re: AW: AW: Differentiated Routing, not only plain rambo-SPF

[shen jing]

Hummel,

the crankback could be assumed, but the difficulty exists with when it
is triggered.

No matter how the two trees are estabilished, the network traffic is
shown to be 
self-similar, and with the increase of bandwidth*delay burst traffic
occurs frequently.

If a router react to transient overload, there may be a huge burden on
dealing with such 
operations. So, I think this mechanism may be adpoted for broken links
but not for congestion.




> 
> Let's assume there are two Smallest Size Tree road systems X1 and X2. X2 detours/avoids the kernel links of X1.
> For some source/destination node pair the total pathes may be different. Or only the section in the middle is different.
> Or only a section close to the source (or close to the dest.) is different. Whatever applies:
> >From the point of congestion on road system X1 the packet my crankback (hereby source and dest. address are swapped)
> to that first node which is also part of X2.
> There  source and dest. address are swapped again,  DSCP-X1 is replaced by DSCP-X2 and the packet is  moved forward
> via X2.
> 
> Heinrich
> 
> -----Ursprščngliche Nachricht-----
> Von: shen jing [mailto:jshen@cad.zju.edu.cn]
> Gesendet: Mittwoch, 14. August 2002 14:21
> An: irtf-rr@puck.nether.net
> Cc: 'Hummel Heinrich'; 'routing-discussion@ietf.org'
> Betreff: Re: AW: Differentiated Routing, not only plain rambo-SPF
> 
> The discussion you mentioned is that of congestion removement by e2e
> mechanism  or by routing. Professor Crowcroft proposed a method
> named ECN++ which trigger a new path that acts when ECN bit is set
> in packet header.
> 
> >
> > Heinrich,
> >
> > -> yes,it is similar;
> > -> but here it is about state-less IP forwarding, i.e. about
> > -> forwarding the individual IP packets, without any
> > -> RSVP path and without any MPLS path.
> >
> >   Oh! Ok...you would like to do Crankback in
> >   connection less IP environments?!?
> >
> >   In such a case, you might find below paper interesting:
> > http://www.ecse.rpi.edu/Homepages/shivkuma/research/papers/te-latest.pdf
> >
> >   There was some discussion in E2E list regarding
> >   pros & cons of this approach. I couldn't find the URL
> >   but I vaguely remember that the subject of the discussion
> >   is "EC++N" or something like that...
> >
> > --

-- 
Jing Shen

State Key Lab of CAD&CG
ZheJiang University(YuQuan)
HangZhou, Z.J. 310027
P.R.China

Tel: +86-571-87932423
Mobile: (0)13516813753
Email: jshen@cad.zju.edu.cn

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