INTRODUCTION:

This FAQ is for the Westell 6100 ADSL modem/router but it might work with other Westell modems.

Westell does not offer telnet, ftp or SNMP in their products making it very hard to collect ADSL line statistical data when the collecting program is not running in Windows.

One obscure and undocumented method for collecting data in Westell modems is via multicasting streams. Multicasting streams use a special IP address in the following range 224.0.0.0 - 224.0.0.255 (224.0.0/24) Local Network Control Block. A device called a Client can join a multicasting stream or group by sending IGMP (Internet Group Management Protocol) packets to the Server requesting to join the group. The Server responds by starting to send multicast packets in the form of UDP packets with a destination address of 224.73.193.62 port 1875.

Once the multicast packets are intercepted a monitoring program can strip the encapsulated data payload and decode it. The following table show some of the identified parameters present in the data payload.

Data payload size is 120 bytes (6100)

Offset Description
00 Not Identified 4 Bytes
04 Up Time Counter 4 Bytes
08 Noise margin UP 2 Bytes
10 Power UP 2 Bytes
12 Attenuation UP 2 Bytes
14 Sync rate UP 2 Bytes
16 Noise margin DW 2 Bytes
18 Power DN 2 Bytes
20 Attenuation DN 2 Bytes
22 Sync rate DW 2 Bytes
24 FEC errors 4 Bytes
28 CRC errors 4 Bytes
32 HEC errors 4 Bytes
36 Signal lost 4 Bytes
40 Frame lost 4 Bytes
44 TX user traffic cell count 4 Bytes
48 RX user traffic cell count 4 Bytes
52 Invalid dropped cells 4 Bytes
56 OAM_control_cell 4 Bytes *Not verified
60 0/21 loopback 4 Bytes *Not verified
64 Encapsulation type 2 Bytes *Not verified
66 rx_aal_pdu 4 Bytes *Not verified
70 tx_aal_pdu 4 Bytes *Not verified
74 Not Identified 24 Bytes
.
98 Ethernet RX frames 4 Bytes
102 Ethernet TX frames 4 Bytes
106 Ethernet discarded frames 4 Bytes
.
. Not Identified 10 Bytes

In addition to joining a multicast group Westell modems require a special UDP exchange to start the multicast stream. The client must send a sequence of special UDP packets to the Westell broadcast address. The following table show this UDP packet exchange:

Client sends a UDP packet with source port 1486 and destination port 2420 data = 0x00,0x0c,0x00
6100 replies with a UDP packet with the model number and serial number

Client sends a UDP packet with source port 1486 destination port 2420 data = 0x00,0x01,0x00
6100 replies with a UDP packet with firmware version and data pump version.

Client sends a UDP packet with source port 1487 destination port 2420 data = 0x00,0x0c,0x00
6100 replies with a UDP packet with the model number and serial number

Client sends a UDP packet with source port 1487 destination port 2420 data = 0x00,0x06
6100 replies with a UDP packet with adsl chipset information

Client sends a UDP packet with source port 1875 destination port 1875 data = 0x00,0x30,0x01,0xe0,0x49,0xc1,0x3e
6100 replies with multicast stream

To stop the multicast stream one single UDP packet is needed:

Client sends a UDP packet with source port 1875 destination port 1875 data = 0x00,0x30,0x00
6100 stops multicast stream.

MONITORING PROGRAMS:

start6100 Will start the multicast stream. »adslm.dohrenburg.net/start6100
stop6100 Will stop the multicast stream. »adslm.dohrenburg.net/stop6100
mcastPoll Will collect ADSL statistical data and print it to the screen. »adslm.dohrenburg.net/mcastPoll

Monitor the following page: »adslm.dohrenburg.net/linux.html for updates.

TO DO:
1. Write statistical data to a file so MRTG or RRDTool can use it.
2. Integrate RRDTool with the collecting program.

Enjoy.