Stackable switch port collapse mechanism
View Patent ↗A method and apparatus for providing data communication between stations on a network which optimizes the amount of resources required for a network switch. A first data frame is encoded with a source station identifier for the first station and a source switch identifier for the first switch. The first data frame is sent from the first switch to the second switch. A station list in the second switch is updated to indicate that the first station is associated with the first switch. Subsequent data frames having the same destination as the first switch are sent directly to the second switch. Any switch on the network need only identify the local ports attached to the switch, plus the number of switches on the network. The task of identifying all of the ports on the network is distributed across all switches on the network.
1. In a data communications network having a plurality of stackable, interconnected switches including a first switch and a second switch, a method of learning associations between stations, ports, and switches in the network, the method comprising:
receiving a data frame from a first station on a first port of the first switch, the data frame having a second station as a destination;
updating a station list in the first switch to indicate that the first station is on the first port;
updating the data frame to indicate that it originated from the first switch;
comparing the second station to the station list in the first switch;
sending the data frame to all of a plurality of ports on the first switch and to all of the plurality of switches on the network if the second station is not found in the station list of the first switch;
receiving a second data frame from a third switch, the second data frame being sent by a third station on a third port of the third switch and having a fourth station as a destination;
updating the station list in the first switch to indicate that the third station is on the third switch;
comparing the fourth station to the station list in the first switch;
sending the second data frame to all of the plurality of ports on the first switch if the fourth station is not found in the station list of the first switch;
receiving a second response frame from the fourth station, the fourth station being on a fourth port of the first switch, the response frame having the third station as a destination;
updating the station list in the first switch to indicate that the fourth station is on the fourth port;
updating the second response frame to indicate that it originated from the first switch; and
sending the response frame to the third switch.
2. The method of claim 1 further comprising:
receiving a response frame from the second station, the second station being on a second port of the second switch, the response frame having the first station as a destination and indicating that it originated from the second switch; and
updating the station list in the first switch to indicate that the second station is on the second switch.
3. The method of claim 2 further comprising:
sending the data frame to the second switch if the second station is found in the station list of the first switch with an indication that the second station is on the second switch.
4. The method of claim 1 further comprising:
receiving a response frame from the second station, the second station being on a second port of the first switch; and
updating the station list in the first switch to indicate that the second station is on the second port.
5. The method of claim 4 further comprising:
sending the data frame to the second port on the first switch if the second station is found in the station list of the first switch with an indication that the second station is on the second port.
6. The method of claim 1 wherein the station list is stored in a content addressable memory (CAM).
7. A switch for use in a data communications network having a plurality of stackable, interconnected switches, the switch comprising:
a plurality of ports including a first port to receive a data frame from a first station, the data frame having a second station as a destination, and a fourth port to transmit a second data frame to a fourth station, the second data frame having a third station as a source, the third station being on a third port of a third switch;
a content addressable memory (CAM) that stores a station list;
means for updating the station list to indicate that the first station is on the first port based on receipt of the data frame;
means for updating the data frame to indicate that it originated from the switch;
means for comparing the second station to the station list in the switch;
means for sending the data frame to all of the plurality of ports on the switch and to all of the plurality of switches on the network if the second station is not found in the station list;
means for updating the station list to indicate that the third station is on the third switch means for comparing the fourth station to the station list;
means for sending the second data frame to all of the plurality of ports on the switch if the fourth station is not found in the station list;
means for receiving a second response frame from the fourth station, the second response frame having the third station as a destination;
means for updating the station list to indicate that the fourth station is on the fourth port;
means for updating the second response frame to indicate that it originated from the switch; and
means for sending the response frame to the third switch.
8. The switch of claim 7 further comprising:
means for receiving a response frame from the second station, the second station being on a second port of a second switch, the response frame having the first station as a destination and indicating that it originated from the second switch; and
means for updating the station list to indicate that the second station is on the second switch.
9. The switch of claim 8 further comprising:
means for sending the data frame to the second switch if the second station is found in the station list of the switch with an indication that the second station is on the second switch.
10. The switch of claim 7 further comprising:
means for receiving a response frame from the second station, the second station being on a second port of the switch; and
means for updating the station list in the switch to indicate that the second station is on the second port.
11. The switch of claim 10 further comprising:
means for sending the data frame to the second port on the switch if the second station is found in the station list of the switch with an indication that the second station is on the second port.
12. A data communication network comprising a plurality of stackable, interconnected switches, each of the plurality of switches comprising:
a plurality of ports including a first port to receive a data frame from a first station, the data frame having a second station as a destination, and a fourth port to transmit a second data frame to a fourth station, the second data frame having a third station as a source, the third station being on a third port of a third switch;
a content addressable memory (CAM) that stores a station list;
means for updating the station list to indicate that the first station is on the first port based on receipt of the data frame;
means for updating the data frame to indicate that it originated from a first switch;
means for comparing the second station to the station list in the first switch;
means for sending the data frame to all of the plurality of ports on the first switch and to all of the plurality of switches on the network if the second station is not found in the station list;
means for receiving a response frame from the second station, the second station being on a second port of a second switch, the response frame having the first station as a destination and indicating that it originated from the second switch; and
means for updating the station list to indicate that the second station is on the second switch;
means for updating the station list to indicate that the third station is on the third switch;
means for comparing the fourth station to the station list;
means for sending the second data frame to all of the plurality of ports on the switch if the fourth station is not found in the station list;
means for receiving a second response frame from the fourth station, the second response frame having the third station as a destination;
means for updating the station list to indicate that the fourth station is on the fourth port;
means for updating the second response frame to indicate that it originated from the first switch; and
means for sending the response frame to the third switch.
13. The data communication network of claim 12 , each of the plurality of switches further comprising:
means for receiving a response frame from the second station, the second station being on a second port of the second switch, the response frame having the first station as a destination and indicating that it originated from the second switch; and
means for updating the station list to indicate that the second station is on the second switch.
14. The data communication network of claim 13 , each of the plurality of switches further comprising:
means for sending the data frame to the second switch if the second station is found in the station list of the first switch with an indication that the second station is on the second switch.
15. The data communication network of claim 12 , each of the plurality of switches further comprising:
means for receiving a response frame from the second station, the second station being on a second port of the first switch; and
means for updating the station list in the first switch to indicate that the second station is on the second port.
16. The data communication network of claim 15 , each of the plurality of switches further comprising:
means for sending the data frame to the second port on the first switch if the second station is found in the station list of the first switch with an indication that the second station is on the second port.