Method for processing ATM cells and a device having ATM cell processing capabilities
View Patent ↗A method and a communication device for processing ATM cells. The communication device includes an input interface adapted to receive an ATM cell that is associated with a PHY value and includes a pair of VCI and VPI fields. The communication device is characterized by comprising a search unit, adapted to search, within a group of memory entries that belong to a memory unit, for a pair of VCI and VPI fields that have values that match the values of the VCI and VPI fields of the received ATM cell, if the received VCI field and VPI fields belong to a first predefined group of VCI and VPI fields. The communication device further includes a processor, connected to the search unit, wherein the processor is adapted to determine a channel identifier of the received ATM cell in response to a result of the search and in response to a PHY value associated with the received ATM cell.
1. A method for processing ATM cells, the method comprises:
receiving at a first input interface a first ATM cell that comprises a first virtual channel identifier (VCI) field and a first virtual path identifier (VPI) field;
in response to receiving the first ATM cell at the first input interface, selecting a first parameter table, wherein the first parameter table is associated with the first input interface;
selecting a first PHY table entry from a first PHY table to determine if the first VCI and first VPI fields of the first ATM cell belong to a first predefined group of VCI and VPI fields, wherein selecting the first PHY table entry is based upon a first PHY value from the first ATM cell, wherein the first PHY table is associated with the first parameter table;
if the first VCI and first VPI fields of the first ATM cell belong to the first predefined group of VCI and VPI fields then:
performing a first search, by a hardware search unit and within a first group of memory entries of a first VCI/VPI table associated with the first PHY table, for a first pair of VCI and VPI fields that matches the first VCI and first VPI fields of the first ATM cell; and
determining a first channel identifier of the first ATM cell in response to a result of the first search; and
processing the first ATM cell without using the first VCI/VPI table if the first VCI and first VPI fields of the first ATM cell do not belong to the first predefined group of VCI and VPI fields.
2. The method according to claim 1 , further comprising selecting the first group of memory entries out of multiple groups of memory entries in response to selecting the first PHY table entry.
3. The method according to claim 2 , wherein each group of memory entries of the multiple groups of memory entries stores different VCI and VPI field values.
4. The method according to claim 1 , wherein processing the first ATM cell comprises applying a hash mechanism.
5. The method according to claim 1 , wherein determining the first channel identifier comprises calculating an address of the first channel identifier based upon the first PHY value and on an address of the first pair of VCI and VPI fields that matches the first VCI and first VPI fields of the first ATM cell.
6. The method according to claim 1 , wherein performing the first search further comprises selectively masking a portion of the first VPI field.
7. The method according to claim 1 , further comprising performing a second search, within the first group of memory entries, for a VCI field that matches the first VCI field of the first ATM cell, in response to a failure of the first search, within the first group of memory entries, for the first pair of VCI and VPI fields that match the first VCI and first VPI fields of the first ATM cell.
8. The method according to claim 1 , further comprising determining an ATM cell policy identifier.
9. The method according to claim 1 , further comprising determining if values of the first VCI field and first VPI field belong to the first predefined group of VCI and VPI field values based on a content of a field stored in the first PHY table entry.
10. The method according to claim 1 , further comprising:
receiving at a second input interface a second ATM cell that comprises a second VCI field and a second VPI field;
in response to receiving the second ATM cell at the second input interface, selecting a second parameter table, wherein the second parameter table is associated with the second input interface;
selecting a second PHY table entry from the PHY table to determine if the second VCI and second VPI fields of the second ATM cell belong to a second predefined group of VCI and VPI fields, wherein selecting the second PHY table entry is based upon a second PHY value from the second ATM cell, wherein the PHY table is associated with the second parameter table;
if the second VCI and second VPI fields of the second ATM cell belong to the second predefined group of VCI and VPI fields then:
performing a second search, by a second hardware search unit and within a second group of memory entries of a VCI/VPI table which may be the first VCI/VPI table or a different VCI/VPI table, for a second pair of VCI and VPI fields that matches the second VCI and second VPI fields of the second ATM cell; and
determining a second channel identifier of the second ATM cell in response to a result of the second search; and
processing the second ATM cell without using the VCI/VPI table which may be the first VCI/VPI table or a different VCI/VPI table if the second VCI and second VPI fields of the second ATM cell do not belong to the second predefined group of VCI and VPI fields.
11. The method according to claim 1 , wherein determining if the first VCI and first VPI fields of the first ATM cell belong to a first predefined group of VCI and VPI fields is based upon a field of the first PHY table entry.
12. A communication device, comprising:
an input interface adapted to receive a first ATM cell that comprises a first virtual channel identifier (VCI) field and first virtual path identifier (VPI) field;
a search unit, adapted to:
select a first parameter table, wherein the first parameter table is associated with the input interface;
select a first PHY table entry from a first PHY table based upon a first PHY value from the first ATM cell, wherein the first PHY table is associated with the first parameter table;
determine if the first VCI and first VPI fields of the first ATM cell belong to a first predefined group of VCI and VPI fields based upon the selecting of the first PHY table entry; and
perform a first search, within a first group of memory entries of a first VCI/VPI table that is stored in a memory unit, for a first pair of VCI and VPI fields that has values that match the values of the first VCI and first VPI fields of the first ATM cell, if the first VCI and first VPI fields of the first ATM cell belong to the first predefined group of VCI and VPI fields; and
a processor, coupled to the search unit, wherein the processor is adapted to determine a first channel identifier of the first ATM cell in response to a result of the first search;
wherein the communication device is configured to process the first ATM cell without using the first VCI/VPI table if the first VCI and first VPI fields of the first ATM cell do not belong to the first predefined group of VCI and VPI fields.
13. The communication device according to claim 12 , wherein the processor is further adapted to select the first group of memory entries out of multiple groups of memory entries in response to selecting the first PHY table entry.
14. The communication device according to claim 13 , wherein each group of memory entries of the multiple groups of memory entries stores different VCI and VPI values.
15. The communication device according to claim 12 , wherein the processor is further adapted to calculate an address of the first channel identifier based upon the first PHY value and on an address of the first pair of VCI and VPI fields that matches the first VCI and first VPI fields of the first ATM cell.
16. The communication device according to claim 12 , wherein the search unit is further adapted to selectively mask a portion of the first VPI field during the first search.
17. The communication device according to claim 12 , wherein the search unit is further adapted to search, within the first group of memory entries, for a VCI field that matches the first VCI field of the first ATM cell, in response to a failure of the first search, within the first group of memory entries, for the first pair of VCI and VPI fields that matches the first VCI and first VPI fields of the first ATM cell.
18. The communication device according to claim 12 , further adapted to determine an ATM cell policy identifier.
19. The communication device according to claim 12 , wherein the communication device is configured to process the first ATM cell by applying a hash mechanism if the first VCI and first VPI fields of the first ATM cell do not belong to the first predefined group of VCI and VPI fields.
20. The communication device according to claim 12 , wherein the processor is further adapted to read a field of the first PHY table entry that is indicative of whether to process the first ATM cell using the first VCI/VPI table or perform another type of ATM processing.
21. The communication device according to claim 12 , further comprising:
a second input interface adapted to receive a second ATM cell that comprises a second VCI field and a second VPI field;
a second search unit adapted to:
select a second parameter table, wherein the second parameter table is associated with the second input interface;
select a second PHY table entry from the PHY table based upon a second PHY value from the second ATM cell, wherein the PHY table is associated with the second parameter table;
determine if the second VCI and second VPI fields of the second ATM cell belong to a second predefined group of VCI and VPI fields based upon the selecting of the second PHY table entry; and
perform a second search, within a second group of memory entries of a VCI/VPI table which may be the first VCI/VPI table or a different VCI/VPI table and that is stored in the memory unit, for a second pair of VCI and VPI fields that has values that match the values of the second VCI and second VPI fields of the second ATM cell, if the second VCI and second VPI fields of the second ATM cell belong to the second predefined group of VCI and VPI fields; and
a second processor adapted to determine a second channel identifier of the second ATM cell in response to a result of the second search; and
the communication device is configured to process the second ATM cell without using the VCI/VPI table which may be the first VCI/VPI table or a different VCI/VPI table if the second VCI and second VPI fields of the second ATM cell do not belong to the second predefined group of VCI and VPI fields.
22. The communication device according to claim 12 , wherein determining if the first VCI and first VPI fields of the first ATM cell belong to a first predefined group of VCI and VPI fields is based upon a field of the first PHY table entry.