Method and system of aggregate multiple VLANs in a metropolitan area network
A method and system is provided in which data packets from multiple customer VLANs are forwarded over a MAN using VLAN aggregation. A layer-2 switch located at the edge of the MAN connects the customer VLANs to the MAN. The edge switch aggregates multiple customer VLANs (the “sub-VLANs”) into one provider VLAN (the “super-VLAN”). When a packet is forwarded from the sub-VLAN to the super-VLAN and vice versa, the edge switch uses modified bridge forwarding rules to exchange the customer-configured VLAN-IDs with the provider-configured VLAN-IDs before transporting the packet over the MAN. The edge switch further uses modified bridge media access control (MAC) address learning rules to isolate one customer's traffic from another's (i.e. isolate one sub-VLAN's traffic from another sub-VLAN's traffic).
1. A system comprising:
a metropolitan area network (MAN);
a first virtual local area network (VLAN);
a second VLAN, wherein the second VLAN subsumes the first VLAN;
a first switch coupled to the first and second VLANs, the first switch to receive from the first VLAN a data packet having a first VLAN ID associated with the first VLAN, to replace the first VLAN ID with a second VLAN ID associated with the second VLAN, and to forward the modified data packet to the second VLAN; and
a second switch coupled to the MAN and the second VLAN, the second switch to receive from the second VLAN the modified data packet and to forward the modified data packet to the MAN.
2. The system of claim 1 , wherein the second VLAN also subsumes a third VLAN, and wherein the first switch further to prevent the modified data packet from the first VLAN from being forwarded to the third VLAN.
3. The system of claim 2 , wherein the first switch to further maintain a forwarding data base (FDB) for the first, second, and third VLANs, wherein each FDB contains one or more media access control (MAC) address entries.
4. The system of claim 3 , wherein the first switch to maintain a FDB for the first, second, and third VLANs comprises the first switch to add a new MAC address entry to the FDB for each of the first, second, and third VLANs when a new MAC address is learned from the first, second, or third VLAN.
5. The system of claim 1 , wherein the second switch further to receive from the MAN a second data packet having the second VLAN ID, to forward the second data packet to the first switch, wherein the first switch to replace the second VLAN ID with the first VLAN ID, and to forward the modified second data packet from the MAN to the first VLAN.
6. The system of claim 1 , wherein the first VLAN ID is obtained from a header encapsulating the data packet.
7. The system of claim 6 , wherein the header encapsulating the data packet is an Institute of Electrical and Electronics Engineers (IEEE) 802.1Q frame tag.
8. The system of claim 1 , wherein the second VLAN ID is obtained from a header encapsulating the data packet.
9. The system of claim 8 , wherein the header encapsulating the data packet is an Institute of Electrical and Electronics Engineers (IEEE) 802.1Q frame tag.
10. The system of claim 1 , wherein the first VLAN ID is obtained from an internal value stored in the first switch.
11. The system of claim 1 , wherein the second VLAN ID is obtained from an internal value stored in the first switch.
12. A method comprising:
receiving a data packet from a first virtual local area network (VLAN) at a first switch coupled to the first VLAN and a second VLAN, wherein the second VLAN subsumes the first VLAN;
verifying a first VLAN ID in the data packet, wherein the first VLAN ID is associated with the first VLAN;
replacing the first VLAN ID with a second VLAN ID associated with the second VLAN; and
forwarding the modified data packet from the second VLAN to a metropolitan area network (MAN) via a second switch.
13. The method of claim 12 , further comprising receiving at the second switch a second data packet from the MAN having the second VLAN ID, replacing the second VLAN ID with the first VLAN ID, and forwarding the modified second data packet to the first VLAN.
14. The method of claim 12 , further comprising obtaining the first and second VLAN IDs from the data packet.
15. The method of claim 12 , further comprising obtaining the first and second VLAN IDs from internal values stored in the first switch.
16. The method of claim 12 , further comprising preventing the data packet originating from the first VLAN from being forwarded to a third VLAN.
17. The method of claim 16 , further comprising maintaining a forwarding data base (FDB) for the first, second, and third VLANs, wherein each FDB contains one or more media access control (MAC) address entries, and adding a new MAC address entry to the FDB for each of the first, second, and third VLANs when a new MAC address is learned from the first, second, or third VLAN.
18. An article of manufacture comprising:
a machine accessible medium including content that when accessed by a machine causes the machine to
receive a data packet from a first virtual local area network (VLAN) at a first switch coupled to the first VLAN and a second VLAN,wherein the second VLAN subsumes the first VLAN;
verify a first VLAN ID in the data packet, wherein the first VLAN ID is associated with the first VLAN;
replace the first VLAN ID with a second VLAN ID associated with the second VLAN; and
forward the modified data packet to a metropolitan area network (MAN) via a second switch.
19. The article of manufacture of claim 18 , further comprising a machine accessible medium including content that when accessed by a machine causes the machine to receive at the second switch from the MAN a second data packet having the second VLAN ID, replace the second VLAN ID with the first VLAN ID, and forward the modified second data packet from MAN to the first VLAN.
20. A switch comprising:
a port for receiving a data packet from a first virtual local area network (VLAN);
an assigner to assign a first VLAN ID to the data packet that identifies the first VLAN;
a verifier to verify that the assigned first VLAN ID matches a value stored in a memory of the switch;
a controller to control the processing of the verified data packet and to replace the verified first VLAN ID with a second VLAN ID that identifies a second VLAN, wherein the second VLAN subsumes the first VLAN; and
a forwarder to forward the modified data packet to a metropolitan area network (MAN).
21. The switch of claim 20 , wherein the assigner further identifies the second VLAN based on the contents of the data packet's source Internet Protocol (IP) address.
22. The switch of claim 20 , wherein the assigner to assign the first VLAN ID comprises the assigner to obtain the first VLAN ID from a header encapsulating the data packet.
23. The switch of claim 20 , further comprising a preventer to prevent the data packet from being forwarded to a third VLAN.
24. The switch of claim 20 , further comprising: a second port for receiving a second data packet from the second VLAN, and wherein the assigner to assign the second VLAN ID to the second data packet that identifies the second VLAN, the verifier to verify that the assigned second VLAN ID matches a second value in the memory of the switch, the controlling to replace the verified second VLAN ID with the first VLAN ID that identifies the first VLAN, and the forwarder to forward the modified second data packet to the first VLAN.