Look up table (LUT) for Point-to-Point Protocol identification (PPP ID)
A Point-to-Point Protocol (PPP) identifier (PPP ID) value of a PPP frame, including data, is converted to an associated Ethernet Virtual Local Area Network (VLAN) tag identifier (ID) value to enable the PPP ID value information to be communicated in an Ethernet frame to the next transmission layer for use in routing the data from the PPP frame.
1. A method for converting a Point-to-Point Protocol (PPP) identifier (PPP ID) value to an Ethernet Virtual Local Area Network (VLAN) tag identifier (ID) value, the method comprising:
receiving a PPP frame, the PPP frame including at least a PPP identifier (PPP ID) value;
converting the PPP ID value to an Ethernet VLAN tag ID value corresponding to the PPP ID value, wherein converting the PPP ID value to an Ethernet VLAN tag ID value corresponding to the PPP ID is based on a PPP ID look up table (LUT) that maps the PPP ID value to the corresponding Ethernet VLAN tag ID value, the PPP ID LUT having a plurality of PPP ID registers, each PPP ID register having stored therein a different PPP ID register value against which the PPP ID value may be compared, wherein the converting is further:
comparing the PPP ID value against the different PPP ID register values to determine whether there is a matching PPP ID register value, the matching PPP ID register value matching the PPP ID value,
determining a corresponding VLAN tag ID register, the corresponding VLAN tag ID register corresponding to the PPP ID register having stored therein the matching PPP ID register value, and
obtaining the VLAN tag ID value from the corresponding VLAN tag ID register; and
outputting an Ethernet frame including the Ethernet VLAN tag ID value corresponding to the PPP ID value.
2. A device for converting a Point-to-Point Protocol (PPP) identifier (PPP ID) value to an Ethernet Virtual Local Area Network (VLAN) tag identifier (ID) value, the device comprising:
at least one input for receiving the PPP ID value from a PPP frame;
a PPP ID look up table (LUT);
a converter for converting the PPP ID value to the Ethernet VLAN tag ID value that corresponds to the PPP ID value; and
at least one output for outputting the Ethernet VLAN tag ID value corresponding to the PPP ID value, wherein the PPP ID LUT has a plurality of PPP ID registers, each PPP ID register having stored therein a different PPP ID register value against which the PPP ID value may be compared, and further wherein the converter has:
a comparator for comparing the PPP ID value against the different PPP ID register values to determine whether there is a matching PPP ID register value, the matching PPP ID register value matching the PPP ID value; and
a multiplexer for determining a corresponding VLAN tag ID register, the corresponding VLAN tag ID register corresponding to the PPP ID register having stored therein the matching PPP ID register value, and further, for pulling into the output the Ethernet VLAN tag ID value from the corresponding VLAN tag ID register.
3. A system for converting a Point-to-Point (PPP) identifier (PPP ID) value from a Packet Over SONET (POS) frame to an Ethernet Virtual Local Area Network (VLAN) tag identifier (ID) value, the system comprising:
a POS framer, the POS framer for receiving the POS frame and for outputting the PPP frame including a PPP ID value and a data value representing data and
a converter, the converter for receiving the PPP ID value and the data value, converting the PPP ID value to the Ethernet VLAN tag ID value, and for outputting an Ethernet frame including the Ethernet VLAN tag ID value and the data value, the Ethernet VLAN tag ID value corresponding to the PPP ID value, wherein the converter further comprises:
at least one input for receiving the PPP ID value from the PPP frame;
a PPP ID look up table (LUT), the PPP ID LUT for receiving the PPP ID value and converting the PPP ID value to the Ethernet VLAN tag ID value that corresponds to the PPP ID value; and
at least one output for outputting the Ethernet VLAN tag ID value corresponding to the PPP ID value, wherein the PPP ID LUT has a plurality of PPP ID registers, each PPP ID register having stored therein a different PPP ID register value against which the PPP ID value may be compared, and further wherein the converter has:
a comparator for comparing the PPP ID value against the different PPP ID register values to determine whether there is a matching PPP ID register value, the matching PPP ID register value matching the PPP ID value; and
a multiplexer for determining a corresponding VLAN tag ID register, the corresponding VLAN tag ID register corresponding to the PPP ID register having stored therein the matching PPP ID register value, and further, for pulling into the output the Ethernet VLAN tag ID value from the corresponding VLAN tag ID register.