Method and apparatus for selective interleaving in a cell-switched network

• US 5,434,855 A
• Filed: 10/28/1994
• Issued: 07/18/1995
• Est. Priority Date: 07/23/1993
• Status: Expired due to Term

• Current Assignee: Enterasys Networks Incorporated (Extreme Networks, Inc.)
• Original Assignee: Digital Equipment Corporation PAT Law Group
• Inventors: Hawe, William R., Thomas, Robert E., Perlman, Radia J., Kaufman, Charles W.
• Primary Examiner(s): MARCELO, MELVIN C
• Application Number:
  US08/331,250
• Time in Patent Office: 263 Days
• Field of Search: 370/60, 370/60.1, 370/61, 370/62, 370/94.1, 370/94.2, 370/94.3, 340/825.02, 340/825.03, 379/202
• US Class Current: 370/394
• CPC Class Codes: H04L 2012/5619 Network Node Interface, e.g. tandem connections, transit switching
• CPC Class Codes: H04L 2012/5649 Cell delay or jitter
• CPC Class Codes: H04L 2012/565 Sequence integrity
• CPC Class Codes: H04L 49/104 Asynchronous transfer mode [ATM] switching fabrics
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections

Abstract

A novel mechanism prevents interleaving of packet cells from different source nodes on the same multicast port group at switches of a multicast virtual circuit in a cell-switched network: however, different cells bound for different multicast port groups may be interleaved. The mechanism comprises specific routing information that is stored in each multicast group port entry of a forwarding table located within each switch of the multicast virtual circuit. The forwarding table also stores information relating to each multicast port group including a virtual circuit value for each port of the multicast group. The specific routing information is provided for each multicast port group entry to notify the switch when data traffic for a particular packet is pending through a port of the multicast group and when that data traffic ceases, i.e., when the "end-of-packet" is reached. This ensures that the packets may be correctly reassembled at the destination nodes.

Claims

1. Apparatus for inhibiting interleave of packet cells transferred from a plurality of source nodes to a plurality of destination nodes by way of a multicast virtual circuit in a cell-switched network, said apparatus comprising:

a plurality of links connected to each of said source nodes and destination nodes; and

at least one switch for interconnecting said links, said switch having a plurality of ports associated with a multicast port group and corresponding to said destination nodes, said switch further having a table with entries for storing specific routing information associated with said multicast port group, said specific routing information indicating when packet cells from one of said source nodes are passing through one of said ports to remaining ones of said ports of said multicast group,

whereby said switch, in response to said specific routing information, inhibits packet cells transferred from another of said source nodes from passing through any of said ports of said multicast port group while said packet cells from said one of said source nodes are passing through said ports of said multicast port group.

2. The apparatus of claim 1 wherein said specific routing information further indicates when passing of said packet cells through said one of said ports ceases.

3. The apparatus of claim 2 wherein said specific routing information comprises a state bit provided for each multicast port group entry.

4. The apparatus of claim 2 wherein said specific routing information comprises a flag provided for each multicast port group entry.

5. The apparatus of claim 4 wherein said flag indicates passing of said packet cells through one of said ports ceases in response to an end-of-packet cell received at said one of said ports.

6. A method for inhibiting interleave of packet cells transferred from a plurality of source nodes to a plurality of destination nodes by way of a multicast virtual circuit in a cell-switched network having a plurality of links connected to each of said source nodes and destination nodes, said network including at least one switch for interconnecting said links, said switch having a plurality of ports associated with a multicast port group and corresponding to said destination nodes, said method comprising the steps of:

storing specific routing information associated with said multicast port group in entries of a table of said switch;

asserting said specific routing information to indicate when packet cells from one of said source nodes are passing through one of said ports to remaining ones of said ports of said multicast group; and

inhibiting, in response to said asserted specific routing information, packet cells transferred from another of said source nodes from passing through any of said ports of said multicast port group while said packet cells from said one of said source nodes are passing through said ports of said multicast port group.