Method for handling IP multicast packets in network switch

• US 20040170176A1
• Filed: 03/09/2004
• Published: 09/02/2004
• Est. Priority Date: 03/17/1999
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Ambe, Shekhar, Kadambi, Shiri
• Granted Patent: US 7,720,055 B2
• Time in Patent Office: Days
• US Class Current: 370/392
• CPC Class Codes: H04L 12/18 for broadcast or conference , e.g. multicast
• CPC Class Codes: H04L 12/42 Loop networks
• CPC Class Codes: H04L 12/46 Interconnection of networks
• CPC Class Codes: H04L 12/4625 Single bridge functionality, e.g. connection of two networks over a single bridge
• CPC Class Codes: H04L 12/4641 Virtual LANs, VLANs, e.g. virtual private networks [VPN] LAN interconnection over a bridge based backbone H04L12/462; encapsulation techniques H04L12/4633; routing of packets H04L45/00; packet switches H04L49/00; virtual private networks for security H04L63/0272
• CPC Class Codes: H04L 12/4645 Details on frame tagging routing of packets H04L45/00; support for virtual LAN H04L49/354
• CPC Class Codes: H04L 12/467 Arrangements for supporting untagged frames, e.g. port-based VLANs
• CPC Class Codes: H04L 12/56 Packet switching systems
• CPC Class Codes: H04L 12/5602 Bandwidth control in ATM Networks, e.g. leaky bucket
• CPC Class Codes: H04L 45/24 Multipath
• CPC Class Codes: H04L 45/245 Link aggregation, e.g. trunking
• CPC Class Codes: H04L 45/54 Organization of routing tables
• CPC Class Codes: H04L 45/742 Route cache; Operation thereof
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/125 by balancing the load, e.g. traffic engineering
• CPC Class Codes: H04L 47/15 in relation to multipoint traffic arrangements for broadcast or multicast in data networks H04L12/18
• CPC Class Codes: H04L 47/2408 for supporting different services, e.g. a differentiated services [DiffServ] type of service
• CPC Class Codes: H04L 47/2441 relying on flow classification, e.g. using integrated services [IntServ]
• CPC Class Codes: H04L 47/2458 Modification of priorities while in transit
• CPC Class Codes: H04L 47/286 Time to live
• CPC Class Codes: H04L 47/43 : Assembling or disassembling of packets, e.g. segmentation and reassembly [SAR]
• CPC Class Codes: H04L 47/50 : Queue scheduling
• CPC Class Codes: H04L 47/6215 : Individual queue per QOS, rate or priority
• CPC Class Codes: H04L 47/6225 : Fixed service order, e.g. Round Robin
• CPC Class Codes: H04L 47/623 : Weighted service order
• CPC Class Codes: H04L 49/102 : using shared medium, e.g. bus or ring
• CPC Class Codes: H04L 49/109 : Integrated on microchip, e.g. switch-on-chip
• CPC Class Codes: H04L 49/201 : Multicast operation; Broadcast operation
• CPC Class Codes: H04L 49/208 : Port mirroring
• CPC Class Codes: H04L 49/254 : Centralised controller, i.e. arbitration or scheduling
• CPC Class Codes: H04L 49/3054 : Auto-negotiation, e.g. access control between switch gigabit interface connector [GBIC] and link
• CPC Class Codes: H04L 49/3081 : ATM peripheral units, e.g. policing, insertion or extraction
• CPC Class Codes: H04L 49/351 : for local area network [LAN], e.g. Ethernet switches
• CPC Class Codes: H04L 49/352 : Gigabit ethernet switching [GBPS]
• CPC Class Codes: H04L 49/354 : for supporting virtual local area networks [VLAN]
• CPC Class Codes: H04L 49/45 : Arrangements for providing or supporting expansion
• CPC Class Codes: H04L 49/602 : Multilayer or multiprotocol switching, e.g. IP switching
• CPC Class Codes: H04L 49/90 : Buffering arrangements
• CPC Class Codes: H04L 49/901 : using storage descriptor, e.g. read or write pointers
• CPC Class Codes: H04L 49/9047 : including multiple buffers, e.g. buffer pools
• CPC Class Codes: H04L 49/9057 : Arrangements for supporting packet reassembly or resequencing
• CPC Class Codes: H04L 49/9073 : Early interruption upon arrival of a fraction of a packet
• CPC Class Codes: H04L 67/10 : in which an application is distributed across nodes in the network software deployment G06F8/60; multiprogramming arrangements G06F9/46
• CPC Class Codes: H04L 69/14 : Multichannel or multilink protocols
• CPC Class Codes: H04L 69/16 : Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]
• CPC Class Codes: H04L 69/161 : Implementation details of TCP/IP or UDP/IP stack architecture; Specification of modified or new header fields

Abstract

A method of switching packets in a network switch includes the step of receiving a packet on a source port of a network switch. Thereafter, the method includes the step of determining whether the network switch has sufficient memory capacity to process the data packet; and if memory capacity is sufficient, then the method reads a selected portion of the packet to determine if the packet is to be sent to a mirrored port. If mirroring is determined, then the method sends the data packet to the mirrored port. The method also includes the step of determining whether the packet is to be sent to a remote CPU for further handling, and sending the data packet to the remote CPU if appropriate. The method additionally includes the step of determining whether the packet is a unicast packet, and if so, placing the packet on an internal communication channel within the network switch for appropriate storing and forwarding. If the packet is not a unicast packet, then the method determines if the packet is a multicast packet. If the packet is determined to be a multicast packet, then performing simultaneous lookups and switching using layer 2 lookup tables and addresses, and layer 3 lookup tables and addresses, thereby providing hybrid multicast handling of the packet.

Claims

1. A method of switching packets in a network switch, said method comprising:

receiving a data packet on a source port of a network switch;

determining whether the network switch has sufficient memory capacity to process the data packet;

if memory capacity is sufficient, reading a selected portion of the packet to determine if the packet is to be sent to a mirrored port;

if mirroring is determined, sending the data packet to the mirrored port;

determining whether the packet is to be sent to a remote CPU for further handling, and sending the data packet to the remote CPU if appropriate;

determining whether the packet is a unicast packet, and if so, placing the packet on an internal communication channel within the network switch for appropriate storing and forwarding;

if the packet is not a unicast packet, determining if the packet is a multicast packet;

if the packet is determined to be a multicast packet, then performing simultaneous lookups and switching using layer 2 lookup tables and addresses, and layer 3 lookup tables and addresses, thereby providing hybrid multicast handling of the packet.

2. A method as recited in claim 1, wherein the simultaneous lookups and switching includes:

searching an IP multicast table to determine if a destination address is contained in the table;

forwarding the packet to the remote CPU if the destination address is not contained in the table;

comparing a time-to-live (TTL) value to a predetermined TTL threshold if the destination address is known;

sending the packet to the CPU if the time-to-live value is below the predetermined TTL threshold;

obtaining a layer 3 port bitmap is from the IP multicast table if the time-to-live value is not below the predetermined TTL threshold;

switching the packet to the destination ports if ports on the layer 3 port bitmap are considered active ports for the network switch;

simultaneously with the searching of the IP multicast table, the method includes examining port filtering bits of the module header to determine whether a first predetermined port filtering value is present;

forwarding the packet to a selected group of ports on the switch if the first predetermined port filtering value is present;

searching a multicast table using a destination key if the first predetermined filtering value is not present;

obtaining a port bitmap from the multicast table if searching the multicast table results in a match, then forwarding the data packet to ports obtained from the port bitmap;

if there is no match, the port filtering bits are examined to see if a second predetermined port filtering value is present;

if the second predetermined port filtering value is present, the packet is dropped; and

if the second predetermined port filtering value is not present, then a destination port bitmap is obtained from a VLAN table, and the data packet is forwarded to ports identified in the destination port bitmap.

3. A method as recited in claim 2, wherein said destination key is formed by combining a destination address and a destination VLAN identification value from a field in the packet.