Illustrated TCP/IP Illustrated TCP/IP
by Matthew G. Naugle
Wiley Computer Publishing, John Wiley & Sons, Inc.
ISBN: 0471196568   Pub Date: 11/01/98  

Previous Table of Contents Next


Chapter 170
Anycast Addressing

Anycast Addressing

•  Similar to a multicast address.
•  Address is sent to a group address (anycast) but the router delivers the datagram to the nearest member of the group.
•  Provides for applications such as file and print servers, time servers, name servers, DHCP, etc.
•  Similar to the NetWare protocol of “Get Nearest Server” request.

An anycast address is similar to a multicast address. The exception here is that a packet sent to an anycast address is routed to the “nearest” interface having that address, using distance as a factor.

A source node sends a datagram addressed as an anycast address. This address will be recognized by all destinations of a given type. The routing system is key here; it is the routing system that delivers the datagram to the nearest server. This has applications to find servers of type file/print, timer, name, DHCP, and so forth.

This concept may sound familiar to those who know the Novell NetWare protocol. Functionally, it is implemented differently, but the concept is the same.


Previous Table of Contents Next