Briefly: Identifier: Any element in the ongoing communication between a user and a network service he uses which is statically bound to the function of correlating the communication's data packets with the communication as a whole.
Address: Any element in a network packet used to calculate the packet's next hop. An address might or might not be used to construct an identifier as well. Locator: An address which is not used to construct an identifier. A locator is only used to calculate the packet's next hop. Identifier Definition: Any element in the ongoing communication between a user and and a network service he uses which is statically bound to the function of correlating the communication's data packets with the communication as a whole. Notes: The RRG observes that an identifier must remain unique within the scope of its use and must persist unchanged over the duration of its use. If not unique, packets may be correlated with the wrong communication. If changed, the user or his computer may not determine the new identifier in a timely manner. Examples: * The Web URL that the person uses to access cnn.com every day going back years and years, would prevent the user from tuning in to CNN and would cause all of his news-scraper programs to fail. * The DNS host name used by the Web URL which if changed would force the URL to change. * The user's login name at the New York Times, used to track the user's activity and build a usage profile which if changed would cause the NYT to lose its prior knowledge about the individual. * The session cookie used to correlate multiple http accesses with a particular user login which if changed would require the user to log in and re-identify himself again. * The TCP transport ID composed of two IP addresses and two port numbers, used to correlate individual IP packets with the TCP connection which if changed would cause the TCP connection to time out and fail. * The IP address which if changed would force the transport ID to change. * The IP address contained within the Web URL which if changed would force the URL to change. * The IP address statically locked by the web browser to the DNS hostname in the Web URL via "DNS Pinning," which if changed would require the URL to change or the browser to restart in order to negate the DNS Pinning. * The MAC address in an IPv6 packet used to construct the IP address which if changed would force the TCP transport ID to change. Address Definition: Any element in a network packet used to calculate the packet's next hop. An address might or might not be used to construct an identifier as well. Examples: * The IP address used both for packet forwarding and as a component of the TCP transport ID. Locator Definition: An address which is not used to construct an identifier. A locator is only used to calculate the packet's next hop. Notes: The RRG observes that when a host or network attaches to the Internet and adopts the use of locators and addresses already contained by the system to which it attached, this new attachment induces no additional routing state on the Internet. However, when the attaching network requires locators or addresses not already contained by the system to which it attached, knowledge about that attachment must be propagated throughout the routing system. Examples: * The MAC address in an IPv4 ethernet packet used to switch packets from one switch port to another within a LAN. * The MPLS label used to route packets to the correct exit router within an AS. Regards, Bill Herrin -- William D. Herrin ................ [email protected] [email protected] 3005 Crane Dr. ...................... Web: <http://bill.herrin.us/> Falls Church, VA 22042-3004 _______________________________________________ rrg mailing list [email protected] http://www.irtf.org/mailman/listinfo/rrg
