RFC 1455 (rfc1455) - Page 1 of 6

Physical Link Security Type of Service

Network Working Group                                   D. Eastlake, III
Request for Comments: 1455                 Digital Equipment Corporation
                                                                May 1993


                 Physical Link Security Type of Service

Status of this Memo

   This memo defines an Experimental Protocol for the Internet
   community.  Discussion and suggestions for improvement are requested.
   Please refer to the current edition of the "IAB Official Protocol
   Standards" for the standardization state and status of this protocol.
   Distribution of this memo is unlimited.

Abstract

   This RFC documents an experimental protocol providing a Type of
   Service (TOS) to request maximum physical link security.  This is an
   addition to the types of service enumerated in RFC 1349: Type of
   Service in the Internet Protocol Suite.  The new TOS requests the
   network to provide what protection it can against surreptitious
   observation by outside agents of traffic so labeled.  The purpose is
   protection against traffic analysis and as an additional possible
   level of data confidentiality.  This TOS is consistent with all other
   defined types of service for IP version 4 in that it is based on link
   level characteristics and will not provide any particular guaranteed
   level of service.

1. Nature of Requirement

   This Internet Protocol addition addresses two potential security
   requirements: resistance to traffic analysis and confidentiality.
   These are described in the two subsections below followed by a
   discussion of why links have different levels of physical security so
   that it is meaningful to request that more secure links be used.

1.1 Traffic Analysis

   At this time all Internet Protocol (IP) packets must have most of
   their header information, including the "from" and "to" addresses, in
   the clear.  This is required for routers to properly handle the
   traffic even if a higher level protocol fully encrypts all bytes in
   the packet after the IP header.  This renders even end-to-end
   encrypted IP packets subject to traffic analysis if the data stream
   can be observed.  While traffic statistics are normally less
   sensitive than the data content of packets, in some cases activities
   of hosts or users are deducible from traffic information.



Eastlake