System and method of modifying data packet tags
View Patent ↗A system and method of managing data packets for transmission in a virtual network are disclosed. In some implementations, a network switch may generally comprise a packet modifier that modifies a VLAN tag state of a packet to be egressed as a function of an egress interface and a VLAN-ID assignment. The modified VLAN tag state may include one or more VLAN tags that are in a different order, or that have a different content, in comparison to the VLAN tags of the packet at the time of ingress.
1. A network switch, comprising
an ingress port to receive a packet of data from a source address in a first network domain that is to be transmitted to a destination address in a second network domain;
a logical interface assignor to assign, in the network switch, at least two virtual local area network (VLAN) tag identifiers to the packet;
a forwarding engine to forward the packet to an assigned egress interface in accordance with information associated with one of the at least two VLAN tag identifiers that are assigned in the network switch;
a packet tag modifier, responsive to a configuration of the egress interface and to one of the at least two VLAN tag identifiers that are assigned in the network switch, to assign an egress tag state to the packet prior to egress at the egress interface; and
a physical egress port associated with the egress interface to egress the packet to the destination address.
2. The network switch of claim 1 wherein the first network domain is a customer network and the second network domain is a service provider network.
3. The network switch of claim 1 wherein the first network domain is a subnetwork and the second network domain is a enterprise network.
4. The network switch of claim 1 wherein said packet tag modifier modifies a tag associated with the packet in accordance with the egress tag state.
5. The network switch of claim 4 wherein said packet tag modifier modifies a value of the tag.
6. The network switch of claim 5 wherein said packet tag modifier modifies content of the tag.
7. The network switch of claim 4 wherein said packet tag modifier removes the tag from the packet.
8. The network switch of claim 4 wherein said packet tag modifier changes an order of at least two tags in the packet.
9. The network switch of claim 4 wherein said packet tag modifier assigns the egress tag state according to an egress tag state table.
10. The network switch of claim 1 wherein the egress tag state is assigned from the group consisting of: untagged; single tagged with a customer virtual local area network (C-VLAN) tag; single tagged with a service provider virtual local area network (S-VLAN) tag; double tagged with a C-VLAN tag first and an S-VLAN tag second; and double tagged with an S-VLAN tag first and a C-VLAN tag second.
11. The network switch of claim 1 wherein each of the at least two VLAN tag identifiers is a VLAN identification (VID) that identifies a VLAN associated with the packet.
12. The network switch of claim 1 further comprising a memory maintaining a egress tag state table and wherein said packet tag modifier comprises logic to access the egress tag state table to assign the egress tag state to the packet.
13. The network switch of claim 12 wherein said packet tag modifier accesses the egress tag state table using a key.
14. The network switch of claim 13 wherein the key is one of the at least two VLAN tag identifiers.
15. The network switch of claim 12 wherein said packet tag modifier accesses the egress tag state table to assign the egress tag state in accordance with said physical egress port.
16. The network switch of claim 12 wherein said memory is a ternary content addressable memory (TCAM).
17. A method of modifying a packet in a virtual local area network (VLAN); said method comprising:
receiving a packet of data from a source address in a first network domain that is to be transmitted to a destination address in a second network domain;
identifying an ingress port at which the packet is received and an ingress tag state of the packet upon ingress;
responsive to said identifying, assigning, after the packet is received at the ingress port, at least two virtual local area network (VLAN) tag identifiers to the packet;
forwarding the packet to an assigned egress interface in accordance with information associated with one of the at least two VLAN tag identifiers that are assigned after the packet is received at the ingress port;
responsive to a configuration of the egress interface and to one of the at least two VLAN tag identifiers that are assigned after the packet is received at the ingress port, modifying an egress tag state of the packet prior to egress at the egress interface; and
egressing the packet to the destination address at a physical egress port associated with the egress interface.
18. The method of claim 17 wherein the first network domain is a customer network and the second network domain is a service provider network.
19. The method of claim 17 wherein the first network domain is a subnetwork and the second network domain is a enterprise network.
20. The method of claim 17 wherein said modifying comprises changing a value of the tag.
21. The method of claim 20 wherein said modifying comprises changing content of the tag.
22. The method of claim 17 wherein said modifying comprises removing the tag from the packet.
23. The method of claim 17 wherein said modifying comprises changing an order of at least two tags in the packet.
24. The method of claim 17 wherein said modifying comprises selecting the egress tag state according to an egress tag state table.
25. The method of claim 24 wherein said modifying further comprises accessing the egress tag state table using a key.
26. The method of claim 25 wherein the key is one of the at least two VLAN tag identifiers.
27. The method of claim 25 wherein said modifying comprises modifying the egress tag state in accordance with the physical egress port.
28. The method of claim 24 wherein the egress tag state table is maintained in a ternary content addressable memory (TCAM).
29. The method of claim 17 wherein said forwarding comprises mapping the packet to the egress interface according to a record in a database.
30. The method of claim 17 wherein the egress tag state is selected from the group consisting of: untagged; single tagged with a customer virtual local area network (C-VLAN) tag; single tagged with a service provider virtual local area network (S-VLAN) tag; double tagged with a C-VLAN tag first and an S-VLAN tag second; and double tagged with an S-VLAN tag first and a C-VLAN tag second.
31. The method of claim 17 wherein each of the at least two VLAN tag identifiers is a VLAN identification (VID) that identifies a VLAN associated with the packet.
32. An Ethernet switch configured and operative to perform the method of claim 17 .