US 5,309,437 A · Bridge-like internet protocol router

Abstract

A device and related method for coupling segments of an extended local area network (LAN) in such a way that message traffic employing inter-network protocols such as TCP/IP will be handled without the difficulties usually associated with bridges, and without the complexity and expense of full IP router capability. The device operates like a bridge for non-TCP/IP traffic. For TCP/IP traffic it operates in a bridge-like manner but maintains a database associating extended LAN segment addresses with port numbers in the device, so that packets can be automatically forwarded over a spanning tree connecting the network segments. A host computer in any network segment can address others in different network segments of the extended LAN as though all were in a single LAN. The device of the invention functions to block the flow of ARP messages and to generate ARP replies that render the device of the invention transparent to hosts within the extended LAN. The device is also transparent to true IP routers, which may still be used to effect communication with points outside the extended LAN.

Claims26

Dependent claims

For use in a configuration of interconnected local area networks (LANs) handling message traffic in accordance with a set of inter-network protocols that use a network addressing scheme, a bridge-like IP router (BLIP), comprising:

multiple ports for attaching the BLIP to multiple segments of an extended LAN;
means for distinguishing received message traffic that uses the inter-network protocols from other message traffic that does not use the protocols;
bridge means for processing the other message traffic exactly in the manner of a conventional bridge, using unique station addresses to determine how to forward the received message traffic;
and
bridge-like means for processing the inter-network protocol traffic in a manner analogous to a bridge, wherein a message packet received from an extended LAN segment attached to the BLIP is forwarded if necessary to at least one other extended LAN segment attached to the BLIP, using network addresses and network segment addresses, instead of unique station addresses, to determine how to forward the message traffic.

2 more elements

For use in a configuration of interconnected local area networks (LANs) handling message traffic in accordance with a set of protocols known as TCP/IP, a bridge-like IP router (BLIP), comprising:

multiple ports for attaching the BLIP to multiple segments of an extended LAN;
means for distinguishing received TCP/IP message traffic from non-TCP/IP message traffic;
bridge means for processing non-TCP/IP message traffic exactly in the manner of a conventional bridge;
and
bridge-like means for processing TCP/IP traffic in a manner analogous to a bridge, wherein a message packet received from an extended LAN segment attached to the BLIP is forwarded if necessary to some subset of the attached extended LAN segments except the one from which the message packet was received at least one other extended LAN segment attached to the BLIP.

2 more elements

For use in a configuration of interconnected local area networks (LANs) handling message traffic in accordance with a set of protocols known as TCP/IP, a bridge-like IP router (BLIP), comprising:

multiple ports for attaching the BLIP to multiple segments of an extended LAN;
means for distinguishing received TCP/IP message traffic from non-TCP/IP message traffic;
bridge means for processing non-TCP/IP message traffic exactly in the manner of a conventional bridge;
and
bridge-like means for processing TCP/IP traffic in a manner analogous to a bridge, wherein a message packet received from an extended LAN segment attached to the BLIP is forwarded if necessary to at least one other extended LAN segment attached to the BLIP;
wherein the bridge-like means includes
means for detecting and discarding ARP messages requesting destination address information,
means for responding to ARP messages by transmitting in reply a message packet containing a special address code, but only if the requested destination address is on a different segment of the same extended LAN as the BLIP,
means for forwarding any received message packet containing the special address code, to at least one other attached extended LAN segment, whereby a host device may transmit to destinations on other extended LAN segments as though the destinations were on the same LAN,
an IP database associating each segment of the extended LAN with a port of the BLIP,
means for updating the IP database by observing each received message and correlating the segment address for each message source with a port through which the message is received,
an ARP database associating each network layer address in attached extended LAN segments with a corresponding data link layer address, and
means for updating the ARP database by sending ARP messages directed to specific network layer addresses and processing ARP replies that contain the corresponding data link layer addresses.

10 more elements

A method of operation of a configuration of interconnected local area networks (LANs) handling message traffic in accordance with a set of protocols known as TCP/IP, the method comprising the steps of:

configuring an extended local area network (LAN) to include a plurality of extended LAN segments connected by bridge-like IP routers (BLIPs);
receiving a packet of data at a BLIP;
determining whether the packet has been transmitted under TCP/IP protocols;
processing non-TCP/IP packets in the manner of a conventional bridge;
and
processing TCP/IP traffic in a manner analogous to a bridge, wherein a message packet received from an extended LAN segment attached to the BLIP is forwarded if necessary to at least one other extended LAN segment attached to the BLIP.

3 more elements

configuring an extended local area network (LAN) to include a plurality of extended LAN segments connected by bridge-like IP routers (BLIPs);
receiving a packet of data at a BLIP;
determining whether the packet has been transmitted under TCP/IP protocols;
processing non-TCP/IP packets in the manner of a conventional bridge;
processing TCP/IP traffic in a manner analogous to a bridge, wherein a message packet received from an extended LAN segment attached to the BLIP is forwarded if necessary to at least one other extended LAN segment attached to the BLIP;
detecting and discarding ARP messages requesting destination address information;
responding to ARP messages with a special address code when the requested destination address is on a different segment of the same extended LAN as the BLIP;
forwarding a message packet having the special address code, to at least one other attached LAN segment, whereby a host device may transmit to destinations on other extended LAN segments as though the destinations were on the same LAN;
maintaining an IP database that associates each segment of the extended LAN with a port of the BLIP, wherein the maintaining step is performed by observing each received message and correlating the segment address for each message source with a port through which the message is received;
maintaining an ARP database that associates each network layer address in attached extended LAN segments with a corresponding data link layer address, wherein the maintaining step is performed by sending ARP messages directed to specific network layer addresses and processing ARP replies that contain the corresponding data link layer addresses;
and
maintaining a router database containing the data link layer addresses of all true IP routers connected to the extended LAN.

9 more elements

Dependencies are inferred from the claim text.

Bridge-like internet protocol router

Life of this patent

Bridge-like internet protocol router

Life of this patent

Abstract

Claims26