Re: BCP regarding TOS transparancy for internet traffic

["Eric A. Hall" <ehall () ehsco com>]

On 5/25/2005 1:54 PM, Kevin Oberman wrote:
> > Date: Wed, 25 May 2005 12:35:56 -0400
> > From: "Eric A. Hall" <ehall () ehsco com>

> > the original bits somewhere. Dunno about now, but I would imagine a few
> > providers have fallen for the "everybody else is doing it" invented
> > justification, and thus became the self-fulfilling claim themselves.

> ESnet does QoS with expedited forwarding enabled in our core. To prevent
> the unauthorized use of these bits, we have long had a policy of
> clearing them at our border for all traffic not authorized for the
> expedited service. If we receive packets marked for less than best
> effort (scavenger) service, the bits are reset.

Here's the correct model (imo):

1) You are under no obligation to provide expedited service to anybody who
hasn't paid for it. Packets marked with flags for services that haven't
been paid for should simply be ignored.

2) Following therefore, you only need to process flags for customers that
have paid for the expedited service.

3) You should only shuffle the bits around if they ask/need you to do it,
since the customer probably wants to flag their important packets/flows
themselves. The default is to not modify -- only to process differently.

4) The default of no-modify should also apply to non-payinng customers
since they may be flagging their packets for special processing on their
own networks (and they don't want the flags to poof away when the traffic
crosses your hop).

In sum, premium packages are for expedited processing, which is what they
are buying. Rewriting any packets without consent/request is not needed
and unrelated, and is bad mojo in general.

-- 
Eric A. Hall                                        http://www.ehsco.com/
Internet Core Protocols          http://www.oreilly.com/catalog/coreprot/