Method and system for exchanging routing information

• US 6,167,444 A
• Filed: 05/08/1998
• Issued: 12/26/2000
• Est. Priority Date: 05/08/1998
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Boden, Edward Barnes, Gebler, Paul Albert Jr., Gruber, Franklin Alfred
• Primary Examiner(s): Dinh, Dung C.
• Assistant Examiner(s): SALAD, ABDULLAHI ELMI
• Application Number:
  US09/075,044
• Time in Patent Office: 963 Days
• Field of Search: 709/223, 709/224, 709/225, 709/235, 709/238, 709/249, 709/250, 709/239, 709/240, 709/241, 709/242, 370/390, 370/401, 713/201
• US Class Current: 709/223
• CPC Class Codes: H04L 12/4604 LAN interconnection over a backbone network, e.g. Internet, Frame Relay
• CPC Class Codes: H04L 45/02 Topology update or discovery
• CPC Class Codes: H04L 45/32 Flooding denial of service attacks H04L63/1458
• CPC Class Codes: H04L 45/52 Multiprotocol routers
• CPC Class Codes: H04L 69/08 Protocols for interworking; Protocol conversion
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

A host computer is operated as a gateway interfacing a plurality of network interfaces in a communication system including local area networks and wide area networks. A redistribution parameter is maintained in a configuration file for each of a plurality of network interfaces, with the redistribution parameter defaulted to *full for local area network interfaces and to *limited for wide area network interfaces. Responsive to receiving a routing update (a route) from a wide area network interface, the route is advertised to interfaces having a redistribution parameter of *full and not to those interfaces having a redistribution parameter of *limited.

Claims

1. Method for operating a host as a gateway interfacing a plurality of network interfaces in a communication system, comprising the steps of:

maintaining in a configuration file a redistribution parameter for each of said plurality of network interfaces;

defaulting said redistribution parameter to *full for local area network interfaces;

defaulting said redistribution parameter to *limited for wide area network interfaces;

responsive to receiving a routing from a wide area network interface, advertising said routing to interfaces having a redistribution parameter of *full and not to those interfaces having a redistribution parameter of *limited.

2. The method of claim 1, comprising the further step of:

overriding the *limited redistribution parameter for a specified wide area network interface to *full.

3. Method for operating a host as a gateway interfacing a plurality of network interfaces including IFC1 and IFC2 in a communication system, where WAN refers to a wide area network, LAN refers to a local area network and CONFIG *FULL refers to a configuration parameter designating an interface as one to receive routing messages and CONFIG *LIMITED refers to a configuration parameter designating a wide area interface as one not to receive routing messages, the method for determining if a routing message received on IFC2 is to be sent (SEND) to an interface IFC1, comprising the steps of:

space="preserve" listing-type="tabular">______________________________________ IF (IFC1 == WAN) &

(IFC2 == WAN) IF IFC1 = CONFIG *FULL SEND ELSE */ IFC1 = CONFIG *LIMITED NO SEND ELSE */ (IFC1 == LAN) &

(IFC2 == LAN) SEND. ______________________________________

4. Method for operating a host as a gateway interfacing a plurality of network interfaces including at least one local area network and at least one wide area network, comprising the steps of:

redistributing knowledge of first routes received from local area networks to all other interfaces; and

redistributing knowledge of second routes received from wide area networks only to local area network interfaces and conditionally upon customer configuration per wide area network interface to the other wide area networks from which knowledge of said second routes was received.

5. Method for operating a host as a gateway interfacing a plurality of network interfaces including at least one local area network and at least one wide area network, comprising the steps of:

maintaining in an interface configuration table a configuration entry for each said interface, said configuration entry including

an interface type indicia identifying said interface as a local area network or a wide area network,

a redistribution bit mask, and

a distribute routes in indicia;

maintaining in a routing table an entry for each of a plurality of routes known to this gateway, said routing entry including

a destination IP address,

a routing bit mask,

responsive to receiving from a first network interface knowledge in a message including a subnet mask of a route to a first destination, selectively updating said routing table with an entry for said first destination including a routing bit mask determined by ORing said subnet mask and said redistribution bit mask; and

thereafter

advertising said route to said first destination selectively to those network interfaces for which said redistribution bit mask and said routing bit mask match.

6. A gateway interfacing a plurality of network interfaces including at least one local area network and at least one wide area network, comprising:

means for redistributing knowledge of first routes received from local area networks to all other interfaces; and

means for redistributing knowledge of second routes received from wide area networks only to local area network interfaces and conditionally upon customer configuration per wide area network interface to the other wide area networks from which knowledge of said second routes was received.

7. A gateway interfacing a plurality of network interfaces including at least one local area network and at least one wide area network, comprising:

an interface configuration table including a configuration entry for each said interface, said configuration entry including

an interface type indicia identifying said interface as a local area network or a wide area network,

a redistribution bit mask, and

a distribute routes in indicia;

a routing table including a routing entry for each of a plurality of routes known to this gateway, said routing entry including

a destination IP address,

a routing bit mask,

means responsive to receiving from a first network interface knowledge in a message including a subnet mask of a route to a first destination for selectively updating said routing table with an entry for said first destination including a routing bit mask determined by ORing said subnet mask and said redistribution bit mask; and

means for advertising said route to said first destination selectively to those network interfaces for which said redistribution bit mask and said routing bit mask match.

8. Apparatus for storing signals for controlling the operation of a digital computer as a gateway interfacing a plurality of network interfaces including at least one local area network and at least one wide area network, said signals comprising:

first redistribution signals for operating said digital computer to redistribute knowledge of first routes received from local area networks to all other interfaces; and

second redistribution signals for operating said digital computer to redistribute knowledge of second routes received from wide area networks only to local area network interfaces and conditionally upon customer configuration per wide area network interface to the other wide area networks from which knowledge of said second routes was received.

9. A digital transmission link for transmitting signals for controlling the operation of a digital computer as a gateway to a plurality of networks including at least one local area network and one or more wide area networks, said signals comprising:

first redistribution signals for operating said digital computer to redistribute knowledge of first routes received from local area networks to all other interfaces; and

second redistribution signals for operating said digital computer to redistribute knowledge of second routes received from wide area networks only to local area network interfaces and conditionally upon customer configuration per wide area network interface to the other wide area networks from which knowledge of said second routes was received.

10. A memory device for storing signals for structuring the components of a digital computer to operate as a gateway interfacing a plurality of network interfaces including at least one local area network and at least one wide area network, said gateway comprising:

means for redistributing knowledge of first routes received from local area networks to all other interfaces; and

means for redistributing knowledge of second routes received from wide area networks only to local area network interfaces and conditionally upon customer configuration per wide area network interface to any other wide area network from which knowledge of said second routes was received.