Type of Service (TOS)

Scott McGrath mcgrath at fas.harvard.edu
Mon May 10 21:49:51 UTC 2004



Cisco and Enterasys definitely pass the TOS bits by default.  You need to
talk to your  engineering group to see whether it is your site's
policy to propagate TOS bits to make sure the TOS bits set by your
appliance will arrive at their destination.

                            Scott C. McGrath

On Mon, 10 May 2004, Vicky Rode wrote:

> Hi,
>
> Do you know by default if the routers pass the TOS bits?
>
>
> regards,
> /vicky
>
>
> Scott McGrath wrote:
>
> >
> > The answer is it depends.  routers _usually_ honor the TOS bits unless
> > they are configured to clear or rewrite them.  We use the TOS bits for
> > designating traffic classes so in some cases we rewrite the TOS bits set
> > by the host so in your case we would modify the TOS bits.
> >
> >                             Scott C. McGrath
> >
> > On Mon, 10 May 2004, Vicky Rode wrote:
> >
> >
> >>Hi there,
> >>
> >>Say if I had a qos appliance installed on networks between a lan and a
> >>wan box would the qos policies be carried across wan end points (point
> >>to point connection)? In other words, will the router retain the TOS
> >>bits across to the other side of the wan connection to provide QoS-style
> >>priority for the packets or will it clear the TOS bits? BTW, the other
> >>side of the wan connection also has the qos appliance sitting between a
> >>lan and a wan box.
> >>
> >>Just so that I'm clear, I'm not talking about an upstream neighbor being
> >>an ISP connection  which I know they will likely ignore the TOS bits
> >>unless I pay them extra for the feature. The above scenario is a point
> >>to point connection to a remote site.
> >>
> >>
> >>Any insight will be appreciated.
> >>
> >>
> >>regards,
> >>/vicky
> >>
> >
> >
>



More information about the NANOG mailing list