Internet protocol (IP) work group routing

Abstract

Apparatus and method wherein multiple router interfaces are assigned the same IP network address, creating an IP work group. This enhances host mobility by allowing, in one embodiment, a host to be relocated anywhere in the work group without requiring reconfiguration of the host. As a further option, host address ranges may be specified (i.e., locked) to designated interfaces of the work group, to enhance security by restricting the allowed host mobility within the work group. An additional advantage is a reduced consumption of network and subnet addresses, because now a single address is used for several physical networks.

1 . A method of routing datagrams from a source to a destination in an IP communications network including routers having multiple router interfaces connecting multiple physical networks, wherein the routers forward IP datagrams based upon IP addresses, the method comprising the steps of: 
 defining an IP work group by assigning multiple router interfaces to a same IP work group address; and    forwarding IP datagrams through the routers based on the IP work group address.    
     
     
         2 . The method of  claim 1  further comprising: 
 specifying IP host address ranges for different router interfaces; and  
 filtering IP datagrams based on the host address ranges.  
 
     
     
         3 . The method of  claim 1 , wherein if an IP datagram contains source and destination host addresses within the same IP work group, forwarding the datagram without performing header and address validation.  
     
     
         4 . The method of  claim 1 , further including configuring a forwarding information base (FIB) with a route for the IP work group.  
     
     
         5 . The method of  claim 1 , further comprising assigning a security level to the IP work group by identifying hosts within the group as “free” in order to permit forwarding to/from any interface, or “secured” in order to permit forwarding to/from a designated interface.  
     
     
         6 . The method of  claim 5 , wherein four levels of security are provided: 
 in a “low” security work group, a host with any physical address is free to reside on any interface as long as its IP address does not lie within specified host address ranges, but if it does fall in any one of the ranges then it must reside on a designated interface for that one range;    in a “medium” security work group, a host's IP address must fall within a specified host address range for a designated interface, but unless a physical address is also specified, the physical address is not constrained;    in a “high” security work group, a host must have a specified host IP address for a designated interlace and have a designated physical address; and    in a “none” security work group, all hosts are free.    
     
     
         7 . The method of  claim 6 , wherein a range table is maintained with the specified host address ranges and their designated interfaces.  
     
     
         8 . A method of providing security in an IP communications network include routers having multiple router interfaces connecting multiple physical networks, wherein the routers forward IP datagrams based on IP addresses, the method comprising the steps of: 
 defining an IP work group by specifying IP host address ranges for different router interfaces; and    filtering IP datagrams based on the host address ranges.    
     
     
         9 . The method of  claim 8 , wherein the defining step includes specifying an IP host address range for a single physical address.  
     
     
         10 . The method of  claim 8 , wherein the defining step includes specifying multiple host address ranges which include the same IP host address to different router interfaces.  
     
     
         11 . A method of increasing host mobility in an IP communications network including multiple physical networks connected by routers having multiple router interfaces, wherein the routers forward IP datagrams based upon IP addresses, the method comprising the steps of: 
 defining an IP work group by assigning multiple router interfaces to a same IP work group address and forwarding IP datagrams based on the IP work group address, and wherein a host is attachable to any interface in the IP work group without requiring reconfiguration of the host IP address.    
     
     
         12 . The method of  claim 11 , including maintaining a host table of IP host addresses and their associated interfaces.  
     
     
         13 . The method of  claim 12 , further comprising reviewing the host table for duplicate IP host addresses and associated interfaces.  
     
     
         14 . The method of  claim 11 , further comprising maintaining a count of known interfaces within the work group.  
     
     
         15 . The method of  claim 11 , further comprising monitoring the hosts heard on each interface and maintaining a host table of IP host addresses and associated interfaces on which each host is heard.  
     
     
         16 . The method of  claim 11 , wherein the host table is maintained as a cache memory accessible by each router interface.  
     
     
         17 . The method of  claim 11 , further comprising: 
 providing a work group forwarding agent for each work group.    
     
     
         18 . The method of  claim 17 , further comprising: 
 maintaining a host table of IP host addresses and their associated interfaces; and    wherein the work group forwarding agent, prior to forwarding a datagram, accesses the host table for the associated interface.    
     
     
         19 . The method of  claim 11 , wherein: 
 the work group forwarding agent sends ARP requests to all interfaces in the work group to resolve an unknown host physical address.    
     
     
         20 . The method of  claim 19 , further comprising: 
 providing an ARP forwarding agent at each interface of the router, which accesses the host table.    
     
     
         21 . The method of  claim 11 , further comprising: 
 maintaining a range table of host IP addresses and associated interfaces on which the hosts may reside; and    prior to forwarding a datagram, accessing the range table to validate a source or destination host.    
     
     
         22 . An IP communications network including multiple physical networks connected by routers having multiple router interfaces, the routers forwarding IP datagrams based upon IP addresses, the network providing increased host mobility and including: 
 means for defining an IP work group by assigning multiple router interfaces to a same IP work group address; and    means for forwarding IP datagrams based on the IP work group address, wherein a host is attachable to any interface in the IP work group without requiring reconfiguration of the host IP address.    
     
     
         23 . An IP communications network including routers having multiple router interfaces connecting multiple physical networks, the routers forwarding IP datagrams based on IP addresses, the network providing enhanced security and including: 
 means for defining an IP work group by specifying IP host address ranges for different router interfaces; and    means for filtering IP datagrams based on the host address ranges.    
     
     
         24 . A router that provides security for preventing unauthorized transmissions comprising: 
 a first interface connectable to a first network;    means for assigning a range of valid IP host addresses to the first interface; and    means for forwarding only IP datagrams transmitted from a host on the first network having a host IP address within the range of valid host addresses.    
     
     
         25 . An apparatus for assigning a plurality of interfaces on an IP communications network to a work group, comprising: 
 means for defining an IP work group by assigning an IP workgroup address to a plurality of interfaces;    means for configuring interfaces to the IP work group;    means for configuring ranges of IP host addresses to associated interfaces of the IP work group; and    means for filtering IP datagrams based upon the host address ranges.