Communicating data units in a communications network that provides failure protection

1. A first node for connecting a customer network element to a network, the first node comprising:

a first communications interface connected to the customer network element; and

a network interface hosting a re-route trunk for communicating with a second node having a connection to the customer network element, and a trunk group for communicating with other nodes of the network, the trunk group comprising a primary trunk and secondary trunk, wherein only one of primary and secondary trunks is active for communicating data units;

a controller for controlling the first node such that, when failure of the first communications interface is detected, data units destined for the customer network element that are received through the trunk group are forwarded through the re-route trunk to the second node, and data units destined for the customer network element that are received through the re-route trunk are dropped.

2. The first node of claim 1 , wherein the primary and secondary trunks comprise primary and secondary provider backbone transports.

3. The first node of claim 1 , wherein the first communications interface comprises an Ethernet user-to-network interface (UNI).

4. The first node of claim 3 , wherein the first communications interfaces comprises a pair of UNIs that together provide an abstract UNI to the customer network element.

5. The first node of claim 3 , wherein the network interface comprises a network-to-network interface (NNI).

6. The first node of claim 1 , wherein the first communications interface is coupled to a link to the customer network element, where the link is part of a link aggregation containing at least another link between the customer network element and the second node.

7. A method for use with a first node connecting a customer network element to a network, the method comprising:

communicating through a first communications interface with the customer network element

communicating through a network interface with a second node via a re-route trunk, and with other nodes of the network over a selected one of a primary trunk and a secondary trunk in a trunk group, the second node having a connection to the customer network element;

when the first communications interface is operational, forwarding data units received by the network interface and destined for the customer network element through the first communications interface; and

in response to detecting failure of the first communications interface:

forwarding data units destined for the customer network element that are received through the trunk group to the second node via the re-route trunk; and

dropping data units destined to the customer network element that are received through the re-route trunk.

8. The method of claim 7 , wherein the network interface of the first node is a network-to-network interface (NNI).

9. The method of claim 8 , wherein the first communications interface to the customer network element comprises a user-to-network interface (UNI).

10. The method of claim 7 , wherein the communicating acts are performed in a network utilizing provider backbone bridging (PBB) that provides for a service provider domain and a customer domain.

11. An article comprising at least one non-transitory machine readable storage medium containing instructions for use in a communications network having customer network elements and a core network having provider network elements, the instructions when executed causing a first provider network element to:

receive a particular data unit destined for a destination customer network element;

determine whether the destination customer network element is connected to the first provider network element;

in response to determining that the destination customer network element is connected to the first provider network element, determine whether a communications interface in the first provider network element to the destination customer network element is functional;

in response to determining that the communications interface in the first provider network element to the destination customer network element is functional, forwarding the particular data unit to the communications interface; and

in response to determining that the communications interface in the first provider network element to the destination customer network element is not functional:

forwarding the particular data unit over a re-route trunk group for routing the particular data unit to a second provider network element having a respective communications interface connected to the destination customer network element; and

dropping data units destined for the destination customer network element received through the re-route trunk group.

12. The article of claim 11 , wherein the instructions when executed cause the first provider network element to further:

in response to determining that the destination customer network element is not connected to the first provider network element, routing the particular data unit over an active one of a primary trunk and a secondary trunk in a trunk group to another provider network element.

13. The article of claim 12 , wherein the communications interface comprises a user-to-network interface (UNI), and wherein the re-route trunk group and primary and secondary trunks include provider backbone transports.

14. The article of claim 11 , wherein forwarding the particular data unit to the communications interface comprises forwarding the particular data unit to the communications interface that is part of a group of communications interfaces to provide failover support, and wherein the second provider network element contains another one of the communications interfaces in the group.

15. The article of claim 14 , wherein the communications interfaces comprise user-to network interfaces (UNIs), and wherein the group of UNIs comprises dual-homed UNIs connected to the destination customer network element.