Dynamic configuration of pseudowire emulation control channel types

1. A device comprising:

a processor to:

send an advertisement of a dynamic control channel capability to a remote device;

establish a pseudowire and a dynamic control channel associated with the pseudowire based on a response from the remote device to the advertisement; and

send to the remote device, over the dynamic control channel, a channel function type message that includes:

a control word having a pseudowire emulation control-status word to indicate that a channel function type word follows the control word, and

the channel function type word having a channel type field that specifies a control channel function.

2. The device of claim 1 , wherein the channel function type word further includes:

a channel function type message type field that indicates if the channel function type message is a request or an acknowledgment.

3. The device of claim 1 , wherein the channel function type message includes a reason for refusing to establish the control channel function.

4. The device of claim 3 , wherein the reason includes at least one of:

the control channel function is already established;

the control channel function is not supported; or

a maximum number of control channel functions that can be supported has been reached.

5. The device of claim 1 , wherein the advertisement includes:

a forwarding equivalence class type-length-value.

6. A method comprising:

sending, by a router, a dynamic control channel in an interface parameter sub-type-length-value of an advertisement label mapping message that is sent to a network device, wherein the sending the dynamic control channel includes:

setting a dynamic control channel value in a control channel types field within a virtual circuit connectivity verification parameter field in the advertisement label mapping message to indicate dynamic control channel capability to the network device, and

setting a connectivity verification types field within the virtual circuit connectivity verification parameter field in the advertisement label mapping message, the set connectivity verification types field indicating that a control channel function is to be negotiated over an established dynamic control channel;

processing a reply label mapping message that is sent from the network device in response to the advertisement label mapping message; and

updating, by the router, a label information base to establish a pseudowire and a dynamic control channel associated with the pseudowire.

7. The method of claim 6 , further comprising:

sending a request control function type message to the network device either to establish a control channel function or to tear down an established control channel function.

8. The method of claim 7 , further comprising:

receiving from the network device a reply channel function type message that acknowledges the request channel function type message.

9. The method of claim 7 , further comprising:

receiving from the network device a reply channel function type message that refuses to establish a control channel function.

10. The method of claim 7 , further comprising:

exchanging with the network device, over the dynamic control channel, control messages for the established control channel function.

11. The method of claim 6 , further comprising:

forming a control message; and

sending the control message over the dynamic control channel.

12. The method of claim 11 , wherein forming a control message includes:

setting a channel type field in a control word so that the channel type field contains a value of a connectivity verification types field in the reply label mapping message; and

inserting the control word in the control message.

13. The method of claim 6 , wherein setting the dynamic control channel value in the control channel types field includes:

setting the control channel types field to a predetermined code.

14. A device comprising:

logic configured to:

receive an advertisement of a dynamic control channel capability from a remote device;

establish a pseudowire and a dynamic control channel associated with the pseudowire based on the advertisement; and

send to the remote device, over the dynamic control channel, a channel function type message that includes:

a control word having a pseudowire emulation control-status word to indicate that a channel function type word follows the control word, and

the channel function type word having a channel type field that specifies a control channel function.

15. The device of claim 14 , wherein the channel function type response includes a reason for refusing to establish the control channel function.

16. The device of claim 15 , wherein the reason includes at least one of:

the control channel function is already established;

the control channel function is not supported; or

a maximum number of control channel functions that can be supported has been reached.