Method and apparatus to facilitate independent protection switching in a distributed network

1. A computer-implemented method comprising:

fixing a logical identifier for a signal line at an input port of an egress time slot interchange (ETSI) of an egress interface of a line of a network element; the ETSI having a plurality of input ports, each having a signal line;

mapping via a translation module coupled to the ETSI a first physical identifier for a first physical signal line to the logical identifier; and

the translation module remapping a second physical identifier for a second physical signal line to the logical identifier responsive to a line failure on the first physical signal line.

2. The method of claim 1 wherein mapping comprises:

writing to a cross connect table and wherein remapping comprises rewriting the cross connect table.

3. The method of claim 1 further comprising:

switching a signal from a second physical signal line to a physical line corresponding to the logical identifier responsive to the remapping.

4. The method of claim 1 wherein fixing comprises:

assigning an identifier to each port of the egress interface during initialization; and

preventing change to the identifier after initialization.

5. The method of claim 1 wherein the signal line is a synchronous optical networking (SONET) line.

6. An apparatus comprising:

a bus interface;

An egress time slot interchange (ETSI) module;

a switch fabric coupled to the ETSI module;

an egress time slot interchange (ETSI) module having a plurality of inputs, each input assigned a logical identifier which remains fixed after initialization; and

a translation module to translate an incoming signal identifier to one of the logical identifiers independent of a physical line on which the signal is received.

7. The apparatus of claim 6 wherein the translation module comprises:

a cross connect table.

8. The apparatus of claim 6 further comprising:

a bus coupled to the bus interface;

a termination module coupled to the bus; and

a line interface having an optical to electrical (O/E) and electrical to optical (E/O) converter.

9. The apparatus of claim 6 wherein the apparatus is implemented as an ASIC on a backplane of a line card.

10. A machine-readable medium having instructions, which when executed by a processor, cause the processor to perform a method, the method comprising:

fixing a logical identifier for a signal line at an input port of an egress time slot interchange (ETSI) of an egress interface of a line card of a network element, the ETSI having a plurality of input ports, each having a signal line; mapping via a translation module coupled to the ETSI a first physical identifier for a

first physical signal line to the logical identifier; and the translation module remapping a second physical identifier for a second physical signal line to the logical identifier responsive to a line failure on the first physical signal line.

11. The machine-readable medium of claim 10 , wherein mapping comprises writing to a cross connect table and wherein remapping comprises rewriting the cross connect table.

12. The machine-readable medium of claim 10 , wherein the method further comprises switching a signal from a second physical signal line to a physical line corresponding to the logical identifier responsive to the remapping.

13. The machine-readable medium of claim 10 , wherein fixing comprises: assigning an identifier to each port of the egress interface during initialization; and preventing change to the identifier after initialization.

14. The machine-readable medium of claim 10 , wherein the signal line a synchronous optical networking (SONET) line.