Auto ATM-VC detection for ATM network access devices
View Patent ↗The system and method allow Customer Premises Equipment Network Access Devices using ATM as a datalink layer transport, to automatically determine what VC addresses are supported by the remote Network Access Concentrator end of the physical connection. A “divide and conquer” approach is used to ping as quickly as possible the most likely VPI/VCI values. The VC discovery mechanism attempts to discover active VP's and pings only VC's on these VP's. If there are no VP replies, it pings VC's to a limited VCI depth covering the entire VP range. The maximum predetermined range of VC's to ping (MAX-PING) and the physical upstream line speed determines the overall amount of time required by this procedure. Direct benefits of the proposed approach include: time and money saved by not having to customize the firmware in each NAD destined for particular Network Service Providers, and improved end-user experience by providing plug-and-play convenience out of the box.
1. A method of configuring a Customer Premises Equipment (CPE) Network Access Device (NAD) to recognize at least one Virtual Channel (VC) address having a Virtual Path Indicator (VPI) and a Virtual Channel Indicator (VCI) to be used for traffic between the NAD and the remote Network Access Concentrator (NAC) over an ATM link, the method comprising:
sending a first plurality of pings to said NAC from said NAD, said pings comprising a prompt for said NAC to reply to said pings;
receiving and recording at least one first response to said first plurality of pings at said NAD, each said first response comprising an active VPI of an active VC used to send said response;
sending a second plurality of pings to a block of VCI's on said active VPI;
receiving and recording at least one second response to said second plurality of pings at said NAD, each said second response comprising a VCI of said active VC used to send said response;
determining said VC address to be used for traffic using said VPI and said VCI of said active VC used in said at least one first response and said at least one second response.
2. A method as claimed in claim 1 , wherein said sending a first plurality of pings comprises sending a first plurality of pings to a plurality of VPI's.
3. A method as claimed in claim 1 , further comprising, when no first response is received, sending a third plurality of pings to a block of VCI's on a block of VPI's.
4. A method as claimed in claim 1 , wherein said sending a first plurality of pings comprises sending a first plurality of pings to a block of VCI's on a block of VPI's.
5. A method as claimed in claim 4 , wherein said block of VPI's is a block of 16 VPI values and said block of VCI's is a block of 32 VCI values.
6. A method as claimed in claim 4 , wherein said sending a first plurality of pings to a block of VCI's on a block of VPI's comprises iteratively sending said first plurality of pings to multiple blocks of VCI's on a block of VPI's and iteratively sending said first plurality of pings to multiple blocks of VPI's.
7. A method as claimed in claim 4 , wherein said block of VPI's is a block of 16 VPI values and said block of VCI's is a block of 32 VCI values.
8. A method as claimed in claim 5 , further comprising steps of defining a predetermined maximum number of VC's to discover, defining a last VC value by dividing said predetermined maximum number of VC's by 256 and aborting said sending a second plurality of pings when said last VC value is attained.
9. A method as claimed in claim 8 , wherein said sending a second plurality of pings is done according to the following blocks of VPI and VCI ranges:
VPI Range
VCI Range
0-15
32-64
.
65-96
.
.
.
.
.
.
.
.
0-15
. . . −LAST-VC
16-31
32-64
.
.
.
.
.
.
16-31
. . . −LAST-VC
.
.
.
.
.
.
240-255
32-64
.
.
.
.
.
.
240-255
. . . −LAST-VC
10. A method as claimed in claim 8 , wherein said defining a predetermined maximum number of VC's to discover comprises
determining an ideal maximum number of VC's to discover;
determining an actual transmission speed over said ATM link;
determining an attainable transmission speed over said ATM link; and
defining said predetermined maximum number of VC's to discover by multiplying said actual transmission speed by said ideal maximum number of VC's to discover and dividing by said attainable transmission speed.
11. A method as claimed in claim 1 , wherein said first plurality of pings is a plurality of GAM F4 loopbacks.
12. A method as claimed in claim 1 , wherein said block of VCI's comprises VCI values from 32 to an upper VCI limit.
13. A method as claimed in claim 12 , further comprising steps of defining a predetermined maximum number of VC's to ping and recording a total number of active VPI and wherein said upper VCI limit is the result of the division of said predetermined maximum number of VC's to ping by a total number of active VPI found.
14. A method as claimed in claim 1 , further comprising steps of defining a maximum number of supported VCI and aborting said receiving and recording at least one second response step if a total of responses received to said second plurality of ping equals said maximum number of supported VCI.
15. A method as claimed in claim 1 , further comprising steps of defining a waiting delay and aborting said receiving and recording at least one second response step if said waiting delay has elapsed.
16. A computer program comprising code means adapted to perform all steps of claim 1 , embodied on a computer readable medium.
17. A system for configuring a Customer Premises Equipment (CPE) Network Access Device (NAD) to recognize at least one Virtual Channel (VC) address having a Virtual Patch Indicator (VPI) and a Virtual Channel Indicator (VCI) to be used for traffic between the NAD and the remote Network Access Concentrator (NAC) over an ATM link, the system comprising:
a ping generator for sending a first plurality of pings to said NAC, said pings comprising a prompt for said NAC to reply to said pings and a second plurality of pings to a block of VCI's on an active VPI;
a response receiver for receiving and recording at least one first response to said first plurality of pings at said NAD, each said first response comprising said active VPI of an active VC used to send said response and at least one second response to said second plurality of pings at said NAD, each said second response comprising a VCI of said active VC used to send said response;
a VC address analyzer for determining said VC address to be used for traffic using said VPI and said VCI of said active VC used in said at least one first response and said at least one second response.
18. A computer program comprising code means adapted to, when loaded in a computer, embody the system of claim 17 , embodied on a computer readable medium.