Subject: hiearchical preference fields

From: Yoshihiro Ohba <[email-masked]>
Date: Tue, 25 Nov 1997 16:48:08 +0900

Hi, 

I'm considering an idea for providing hierarchical preference
fields used for differenciated service.

Consider the case where a user sends packets which go through
several ISPs.

If the packets are to be marked not only at the ingress of the
first ISP, but also at each ISP along the path, the original
preference field may be overwritten by the downstream marking
routers.  The original preference field can reflect
per-flow(non-aggregate) traffic property or importance of each
packet, but it would be lost.

If we assign hierarchically separated preference fields for
users and for ISPs (at least two bits are required for this
assignment), it is possible to hold the user's preference
throughout the network, even if there are multiple marking
entities in the network. Of course, ISPs may mark their
preference field, depending on the value of the user's
preference field.

Thank you for your comments in advance.

Yoshihiro Ohba (Toshiba Corp.)