Re: Comments on draft-katz-yeung-traffic-08.txt

[Sina Mirtorabi <[e-mail]>]

Rohit,

> -----Original Message-----
> From: Mailing List [mailto:[e-mail]]On Behalf Of Rohit
> Dube
> Sent: Saturday, October 19, 2002 11:02 AM
> To: [e-mail]
> Subject: Re: Comments on draft-katz-yeung-traffic-08.txt
>
>
> Hello Naiming,
>
> Thanks for your thoughtful comments. There are two ways one can
> look at TE over multi-access links -
>
> a) Only 2 devices are allowed. This was my interpretation based
>    on section 1.2. My take is that if the condition is violated
>    (ie there are more than 2 devices) one needs to spell out
>    how to react to this.

this is not how I would interpret.
section 1.2 of the draft states:

"The extensions specified in this document capture the reservation state of
point-to-point links. The reservation state of multiaccess links is not
accurately _reflected_, except in the special case that there are only two
devices in the multiaccess subnetwork."


> b) More than 2 devices are allowed which can work given the
>    limitations you list below. If this is allowed, we need
>    to explicitly say so and indicate any additional procedures
>    in the draft.
>

yes this is how I would read the draft...
as far as for additional procedure, what else is needed to define a TE over
multi-acess link having more than two attached routers? ( given the
limitation for reservation state )

since 'Maximum Reservable Bandwidth' is configurable it is up to the
operator to set a value that reflect a bit better the number of routers
attached to the multi-acess network for example if there are N routers
attached and we do not want to oversubscribe one could set

Maximum Reservable Bandwidth <= Maximum Bandwidth / ( N-1 )
where N is the number of routers attached to multi-acess link


Sina


> Either way, I think the item needs to be clarified.
>
> Best,
> --rohit.
>
> On Fri, 18 Oct 2002 23:07:55 -0700 Naiming Shen writes:
> =>there is no need to withdraw TE LSAs while more than two routers
> =>start to exist on the multi-access network. the TE draft says
> =>clearly there will be limitations(verses the p2p link), but this
> =>does not at all mean you can not run TE on that multi-access link
> =>with multiple-routers. it's perfectly "fine" to setup TE tunnels
> =>with multiple routers over the same multi-access link.
> =>
> =>will this cause problem in terms of congestion? yes, it can. but
> =>
> => - even over p2p TE links, we only reserve the bandwidth for
> =>   the TE links, we can still "overbook" the bandwidth and congest
> =>   the p2p TE links.
> =>
> => - TE is usually used to route traffic for the purpose of saving
> =>   cost in the long-haul p2p links. those multi-router/multi-access
> =>   link usually is close to the edge of the network. even there is
> =>   congestion going on, there probably is not much you can do to
> =>   route around them. If there is congestion, simple add more
> =>   bandwith there and the cost should be low.
> =>
> =>since there will be a need to do TE with multiple routers on a LAN,
> =>i think specifying the remote ip of 0.0.0.0 is OK, the draft probably
> =>should say "or this TLV can be omitted". specifying a real IP address
> =>even in the case of only two routers on the LAN does not sound right.
> =>for p2p link, you have to specify the neighbor IP address, since
> =>otherwise, in the case of parallel p2p links, there will be no
> =>other indication to flag the match at both ends. for LAN, you have
> =>the DR interface address to tie them ends together.
> =>
> =>thanks.