Interswitch link mechanism for connecting high-performance network switches
First Claim
1. Apparatus for efficiently transporting packets between ports of different switches in a network on the basis of virtual local area network (VLAN) associations among those ports, the packet comprising a destination address field which identifies a destination network address and a source address field which identifies a source network address, the VLAN associations specified by a VLAN identifier of the packet, the apparatus comprising:
- an interswitch link (ISL) connection; and
ISL source and destination port interface circuitry coupled to the ISL connection for interconnecting the different switches, the ISL source port interface circuitry encapsulating the packets by appending source and destination ISL addresses to the packets prior to transferring the encapsulated packets over the ISL link, the destination ISL address defining the ISL destination port interface circuitry for receiving the packets within a destination switch and the source ISL address defining the ISL source port interface circuitry transmitting the packets within a source switch, the ISL destination port interface circuitry decapsulating the encapsulated packets to remove the source and destination ISL addresses appended thereto, and thereafter forwarding the packets to the correct port as specified by the VLAN identifier.
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Accused Products
Abstract
An encapsulation mechanism efficiently transports packets between ports of different switches in a network on the basis of, inter alia, virtual local area network (VLAN) associations among those ports. The switches are preferably interconnected by a novel interswitch link (ISL) mechanism that appends ISL destination and source information, along with ISL error detection information, to VLAN-modified packets. The ISL mechanism keeps the VLAN associations of the packets intact during transfer between the switches in accordance with a high-performance switching bus architecture.
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Citations
20 Claims
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1. Apparatus for efficiently transporting packets between ports of different switches in a network on the basis of virtual local area network (VLAN) associations among those ports, the packet comprising a destination address field which identifies a destination network address and a source address field which identifies a source network address, the VLAN associations specified by a VLAN identifier of the packet, the apparatus comprising:
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an interswitch link (ISL) connection; and ISL source and destination port interface circuitry coupled to the ISL connection for interconnecting the different switches, the ISL source port interface circuitry encapsulating the packets by appending source and destination ISL addresses to the packets prior to transferring the encapsulated packets over the ISL link, the destination ISL address defining the ISL destination port interface circuitry for receiving the packets within a destination switch and the source ISL address defining the ISL source port interface circuitry transmitting the packets within a source switch, the ISL destination port interface circuitry decapsulating the encapsulated packets to remove the source and destination ISL addresses appended thereto, and thereafter forwarding the packets to the correct port as specified by the VLAN identifier. - View Dependent Claims (2, 3, 4, 5)
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6. An encapsulation mechanism for efficiently transporting packets between first end second switches in a network, the packet comprising a destination address field which identifies a destination network address and a source address field which identifies a source network address, the mechanism comprising:
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an interswitch (ISL) link; and port interface circuitry coupled to the ISL link for interconnecting the switches, the port interface circuitry comprising a media access control (MAC) interface circuit coupled to a direct memory access (DMA) engine by way of ISL encapsulation and decapsulation circuits, the ISL encapsulation circuit encapsulating the packets at the first switch by appending source and destination ISL addresses to the packets prior to transferring the encapsulated packets over the ISL link, the source ISL address defining source pen interface circuitry comprising the ISL encapsulation circuit configured to transmit the packets within the first switch and the destination ISL address defining destination port interface circuitry comprising the ISL decapsulation circuit configured to receive the packets within the second switch, the ISL decapsulation circuit decapsulating the encapsulated packets at the second switch to remove the appended source and destination ISL addresses. - View Dependent Claims (7)
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8. A method for efficiently transporting a frame between network entities coupled to ports of first and second switches in a network on the basis of virtual local area network (VLAN) associations among those ports, the frame comprising a destination address field which identifies a destination network address and a source address field which identifies a source network address, the method comprising the steps of:
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driving the frame over a first switching bus to first interswitch link (ISL) port interface circuit of the first switch; encapsulating the frame with source and destination ISL addresses at an ISL encapsulation circuit of the first ISL port interface circuit, the source ISL address defining the first ISL port interface circuit transmitting the frame within the first switch and the destination ISL address defining a second ISL port interface circuit receiving the frame within the second switch; transferring the encapsulated frame over an ISL link to the second ISL port interface circuit of the second switch; decapsulating the encapsulated frame at an ISL decapsulation circuit of the second ISL port interface circuit; and forwarding the decapsulated frame over a second switching bus of the second switch. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification