Remote communication server with automatic filtering

• US 5,530,703 A
• Filed: 09/23/1994
• Issued: 06/25/1996
• Est. Priority Date: 09/23/1994
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: 3Com Corporation (HP Inc.)
• Inventors: Ko, Alan, Sun, Shirley (Tsyr-Yi), Liu, Vince
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): Nguyen, Chau T.
• Application Number:
  US08/311,066
• Time in Patent Office: 641 Days
• Field of Search: 370/60, 370/85.13, 370/94.3, 370/85.14, 370/94.2, 370/94.1, 370/110.1, 370/85.12, 370/92, 370/85.15, 370/60.1, 370/61, 340/825.52
• US Class Current: 370/255
• CPC Class Codes: H04L 12/4625 Single bridge functionality, e.g. connection of two networks over a single bridge
• CPC Class Codes: H04L 63/02 for separating internal from external traffic, e.g. firewalls

Abstract

Unneeded broadcast and multicast packets are blocked by a remote access server from pass through on a private or switched circuit communication link to a remote node of an corporate LAN, if they relate to protocols not in use by the remote node, or involve information which the remote node does not need. The remote access server includes logic which automatically learns the protocols which the remote node is relying upon, and configures filtering logic for the multi-destination packets in response to the learned protocols. The server executes a method for managing pass through of multi-destination packets, including (1) learning a protocol used by the remote node in response to a packet transmitted to the network by the remote node; (2) storing an identifier of the learned protocol; (3) identifying a protocol of a multi-destination packet in the network; and (4) selecting multi-destination packets to be forwarded to the remote node in response to the stored identifier of the protocol in use by the remote node, and the identified protocol of the multi-destination packet. In addition, a technique for bypasssing the protocol based filtering includes storing addresses provided by the remote node in a multicast address table of multi-destination packets to be forwarded to the remote node; and selecting multi-destination packets to be forwarded to the remote node if the multi-destination packet has a multicast address in the multicast address table.

Claims

1. An apparatus which manages transfer of multi-destination packets from a local network to a remote node, comprising:

a first port for communication with the remote node;

a second port for communication with the local network;

incoming packet sender resource, coupled to the first and second ports, which forward packets originated by the remote node from the first port to the second port;

learning logic, coupled with the incoming packet sender resource, which learns and stores identifiers of network protocols associated with packets forwarded from the first port to the second port;

filtering logic, coupled with the second port and the learning logic, which identifies network protocols associated with multi-destination packets originated in the local network, and selects multi-destination packets in response to identified network protocols and the stored identifiers of network protocols, to be forwarded to the remote node; and

outgoing packet sender resource, coupled with the filtering logic and to the first and second ports, which forward multi-destination packets selected by the filtering logic from the second port to the first port.

2. The apparatus of claim 1, wherein the learning logic determines a network protocol of a packet in response to protocol specific information in the packet.

3. The apparatus of claim 1, wherein the filtering logic determines a network protocol of a packet in response to protocol specific information in the packet.

4. The apparatus of claim 1, wherein the learning logic determines a network protocol of a packet in response to protocol specific information in the packet, and independent of a network destination address of the packet.

5. The apparatus of claim 4, wherein the learning logic determines the network protocol of a packet independent of a MAC level address of the packet.

6. The apparatus of claim 1, wherein packets in the local network have a packet type field, and the learning logic determines the network protocol of a packet in response to the packet type field.

7. The apparatus of claim 1, wherein packets in the local network have a source service access point (SSAP) field, and the learning logic determines the network protocol of a packet in response to the source service access point field.

8. The apparatus of claim 1, wherein the filtering logic includes resources to select multi-destination packets within a limited subset of a set of multi-destination packet types used by a given protocol.

9. The apparatus of claim 8, including resources to identify multi-destination packets within the subset of packet types based upon one or more of packet type fields, source service access point (SSAP) fields and network-specific command fields.

10. The apparatus of claim 1, wherein the learning logic includes resources to detect when an unknown protocol is used by the remote node, to learn characteristics of packets according to the unknown protocol, and the filtering logic includes resources to select for forwarding to the remote node multi-destination packets which have the learned characteristics.

11. The apparatus of claim 1, including resources which store multi-destination addresses supplied by a user of the remote node, and wherein the filtering logic is responsive to the stored multi-destination addresses to select multi-destination packets to be forwarded from the second port to the first port independent of a network protocol associated with the packet.

12. The apparatus of claim 1, wherein the multi-destination packets include broadcast packets.

13. The apparatus of claim 1, wherein the first port comprises an interface to a switched network.

14. The apparatus of claim 1, wherein the first port comprises a point-to-point connection to the remote node.

15. The apparatus of claim 1, wherein the filtering logic includes a plurality of protocol specific filters, and logic for enabling and disabling the protocol specific filters in response to the stored identifiers of network protocols.

16. A method for managing pass through of multi-destination packets from a network across a communication link to a remote node, comprising:

learning a protocol used by the remote node in response to a packet transmitted to the network by the remote node and providing a learned protocol identifier;

storing the learned protocol identifier;

identifying protocols of multi-destination packets originated in the network; and

selecting a particular multi-destination packet received from the network to be forwarded to the remote node in response to a relationship between the learned protocol identifier and the protocol of the particular multi-destination packet.

17. The method of claim 16, including:

storing addresses provided by the remote node in a multicast address table of multi-destination packets to be forwarded to the remote node; and

selecting multi-destination packets to be forwarded to the remote node if the multi-destination packet has a multicast address in the multicast address table.

18. The method of claim 16, wherein the step of learning includes determining whether a packet has a protocol specific information in the packet.

19. The method of claim 16, wherein the step of identifying includes determining whether a packet has a protocol specific information in the packet.

20. The method of claim 16, wherein packets in the network have a packet type field, and the step of learning includes determining the network protocol of a packet in response to the packet type field.

21. The method of claim 16, wherein packets in the network have a source service access point (SSAP) field, and the step of learning includes determining the network protocol of a packet in response to the source service access point field.

22. The method of claim 16, wherein the step of selecting includes selecting multi-destination packets within a limited subset of a set of multi-destination packet types used by a given protocol.

23. The method of claim 22, including identifying multi-destination packets within the subset of packet types based upon one or more of packet type fields, source service access point (SSAP) fields and network-specific command fields.

24. The method of claim 16, wherein the step of learning includes detecting when an unknown protocol is used by the remote node, and learning characteristics of packets according to the unknown protocol, and the step of filtering includes selecting for forwarding to the remote node multi-destination packets which have the learned characteristics.

25. The method of claim 16, wherein the network comprises an carrier sense, multiple access with collision detection CSMA/CD network.

26. The method of claim 16, wherein the network comprises a token passing ring network.

27. An apparatus which manages transfer of broadcast and multicast packets from a local area network to a remote node, comprising:

a first port which serves a switched network link which provides a path to the remote node;

a second port which serves the local area network;

incoming packet sender resource, coupled to the first and second ports, which forward packets originated by the remote node from the first port to the second port;

learning logic, coupled with the incoming packet sender resource, which learns network protocols associated with packets forwarded from the first port to the second port in response to protocol specific information in the packets, and stores identifiers of learned protocols;

filtering logic, coupled with the second port and the learning logic, including a plurality of protocol specific filters, and logic for enabling and disabling the protocol specific filters in response to the stored identifiers of network protocols, the filtering logic identifying network protocols associated with broadcast and multicast packets originated in the local network in response to protocol specific formats of the packets, and selects broadcast and multicast packets to be forwarded to the remote node in response to identified network protocols and the enabled and disabled protocol specific filters; and

outgoing packet sender resource, coupled with the first and second ports and the filtering logic, which forward unicast packets addressed to the remote node and which forward broadcast and multicast packets selected by the filtering logic from the second port to the first port.

28. The apparatus of claim 27, wherein packets in the local area network have a packet type field, and the learning logic determines the network protocol of a packet in response to the packet type field.

29. The apparatus of claim 27, wherein packets in the local area network have a source service access point (SSAP) field, and the learning logic determines the network protocol of a packet in response to the source service access point field.

30. The apparatus of claim 27, wherein the filtering logic includes resources to select multi-destination packets within a limited subset of a set of multi-destination packet types used by a given protocol.

31. The apparatus of claim 30, wherein the resources identify multi-destination packets within the subset of packet types based upon one or more of packet type fields, source service access point (SSAP) fields and network-specific command fields.

32. The apparatus of claim 27, wherein the learning logic includes resources to detect when an unknown protocol is used by the remote node, to learn characteristics of packets according to the unknown protocol, and the filtering logic includes resources to select for forwarding to the remote node multi-destination packets which have the learned characteristics.

33. The apparatus of claim 27, including resources which store multicast addresses supplied by the remote node, and the filtering logic is responsive to the stored multicast addresses to select multicast packets to be forwarded from the second port to the first port independent of a network protocol associated with the packet.

34. The apparatus of claim 27, wherein the local area network comprises an carrier sense, multiple access with collision detection CSMAICD network.

35. The apparatus of claim 27, wherein the local area network comprises a token passing ring network.