LAN/ATM switch having local packet switching and an ATM core fabric
View Patent ↗A device for switching data packets providing for local packet switching and non-local ATM switching. The device provides a packet switch coupled with LAN ports and provides for local switching between the LAN ports over the packet switch. Packets not known to be destined for data terminal equipment coupled with one of the ports are segmented and switched over an ATM backplane, switch or network.
1. A first module implemented within a switch along with at least a second module and a backplane coupling the first and second modules, the first module comprising:
a first port to receive a packet; and
a packet switch coupled to the first port, the packet switch to provide for local switching of the packet utilizing a local port destination table and a destination tag, the local port destination table containing addresses of equipment attached to the first port and being maintained by negative forwarding, the destination tag comprising a multicast field to indicate at least two ports on the first and second modules to receive the packet.
2. The first module of claim 1 further comprising a segmentation and reassembly (SAR) circuit coupled to the packet switch.
3. The first module of claim 1 , wherein the first port includes a port interface, the port interface being coupled to the packet switch.
4. The first module of claim 3 , wherein the port interface is a Medium Access Control (MAC) circuit.
5. The first module of claim 3 , wherein the port interface is an Ethernet interface circuit.
6. The first module of claim 1 , wherein when the packet switch determines that a second port on the second module being implemented within the switch is targeted to receive the packet, the packet switch utilizes the destination tag for routing of the packet to the second module over the backplane.
7. The first module of claim 1 , wherein the destination tag utilized by the packet switch further comprises a port field.
8. The first module of claim 7 , wherein the port field of the destination tag is used to specify a destination port for the packet when the multicast field is set to a first value in order to support a point-to-point transmission of the packet to the destination port.
9. The first module of claim 8 , wherein the first value is a result in which each bit of the multicast field of the destination tag is zero.
10. The first module of claim 8 , wherein the first value is a result in which each bit of the multicast field of the destination tag has a same value.
11. The first module of claim 8 , wherein the bits associated with the port field are used for multicast operations when the multicast field is set to a second value differing from the first value.
12. The first value of claim 11 , wherein the second value includes at least one bit of the multicast field being non-zero.
13. The first module of claim 1 being adapted for coupling to the backplane being an Asynchronous Transfer Mode (ATM) backplane.
14. A first module implemented within a switch adapted for coupling to a backplane and a second module, the first module comprising:
a port; and
a packet switch coupled to the port, the packet switch to provide for local switching of a packet by utilizing a local port destination table and a destination tag, the local port destination table containing addresses of equipment attached to the port and being maintained by negative forwarding, the destination tag comprising (i) a multicast field to indicate ports associated with the first, and second modules to receive a packet when the packet switch is supporting multicast routing of the packet and (ii) a port field to specify a destination port to receive the packet when the packet switch is supporting point-to-point forwarding of the packet.
15. The first module of claim 14 further comprising a segmentation and reassembly (SAR) circuit coupled to the packet switch.
16. The first module of claim 14 , wherein the port includes a port interface, the port interface being coupled to the packet switch.
17. The first module of claim 16 , wherein the port interface is a Medium Access Control (MAC) circuit.
18. The first module of claim 16 , wherein the port interface is an Ethernet interface circuit.
19. The first module of claim 14 , wherein the packet undergoes the multicast routing in lieu of the point-to-point forwarding when the multicast field of the destination tag is set to a first predetermined value.
20. The first module of claim 19 , wherein the first predetermined value is equal to a value in which at least one bit of the multicast field of the destination tag is non-zero.
21. The first module of claim 14 , wherein the packet undergoes point-to-point forwarding to the destination port when to the multicast field of the destination tag is set to a first predetermined value.
22. The first module of claim 21 , wherein the first predetermined value includes each bit of the multicast field of the destination tag being zero.
23. the first module of claim 21 , wherein the first predetermined value includes each bit of the multicast field of the destination tag being set to a same logic level.
24. A method of routing a packet, the method comprising:
maintaining a local port destination table containing addresses of equipment attached to a port in a first module using negative forwarding;
retrieving a packet including a destination address on the port of the first module;
if the destination address does not match the addresses in the local port destination table, using the destination address by the first module to determine whether the packet is to be routed to a second module over a backplane, and utilizing a destination tag instead of the destination address for routing the packet over the backplane from the first module to the second module, the destination tag being used to support either multicast routing of the packet or point-to-point forwarding of the packet.
25. The method of claim 24 , wherein the destination tag comprises a first field to specify ports associated with the first and second modules to receive the packet during the multicast operations and a second field to specify a destination port to receive the packet during the point-to-point forwarding when the first field is set to a specified value.
26. The method of claim 25 , wherein the specified value of the first field is equal to a result when all bits of the first field are zero.
27. The method of claim 25 , wherein the specified value is equal to a result when all bits of the first field are the same.
28. The method of claim 25 , wherein the packet is routed to a grouping including the ports when the first field of the destination tag is set to a value different than the specified value.
29. The method of claim 28 , wherein the value is equal to a result when any bit of the first field is non-zero.
30. The first module of claim 1 wherein the packet switch forwards the packet to another segment if a destination address of the packet matches with one of the addresses in the local port destination address table and a forwarding special rule applies.
31. The first module of claim 1 wherein the packet switch does not forward the packet if a destination address of the packet matches with one of the addresses in the local port destination address table and none of forwarding special rule applies.
32. The first module of claim 14 wherein the packet switch forwards the packet to another segment if a destination address of the packet matches one of the addresses in the local port destination address table and a forwarding special rule applies.
33. The first module of claim 14 wherein the packet switch does not forward the packet if a destination address of the packet matches one of the addresses in the local port destination address table and none of forwarding special rule applies.
34. The method of claim 24 further comprising:
if the destination address matches one of the addresses in the local port destination address table and a forwarding special rule applies, forwarding the packet to another segment according to the forwarding special rule.
35. The method of claim 24 further comprising:
if the destination address matches one of the addresses in the local port destination address table and none of forwarding special rules applies, not forwarding the packet.