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Below is described the current dbeacon protocol version 1.
All dbeacon messages have a common header of 4 bytes. This header includes a
magic value, the protocol version and message type.
-------------------------
| 0 | 1 | 2 | 3 |
-------------------------
| 0xbeac | 1 | T |
-------------------------
There are two types of messages: Probes (0) and Reports (1).
Probes
------
Probes are very simple packets which are used to gather statistics about hosts.
-------------------------
| 0 | 1 | 2 | 3 |
-------------------------
| 0xbeac | 1 | 0 |
-------------------------
| sequence number |
-------------------------
| timestamp |
-------------------------
Reports
-------
Reports are used to report local stats to other beacons, advertise known
addr<->name mappings, etc.
-------------------------
| 0 | 1 | 2 | 3 |
-------------------------
| 0xbeac | 1 | 1 |
-------------------------
| TTL |
-------
Following this initial header, several blocks may follow, encoded using a simple
TLV format. TTL is the original TTL when the report was sent.
Each TLV block is started by the TLV header, which consists of 2 bytes, one for
the block type, the second for the block length. The following types are
defined as of current date:
enum {
T_BEAC_NAME = 'n',
T_ADMIN_CONTACT = 'a',
T_SOURCE_INFO = 'I',
T_ASM_STATS = 'A',
T_SSM_STATS = 'S'
};
T_BEAC_NAME and T_ADMIN_CONTACT are strings, non-zero terminated.
T_SOURCE_INFO has the following format:
-------------------------
| 0 | 1 | 2 | 3 |
-------------------------
| source addr |
-------------------------
| (cont) |
-------------------------
| (cont) |
-------------------------
| (cont) |
-------------------------
| port |
-------------
Following addr/port, other TLVs may be encoded inside the T_SOURCE_INFO. These
include T_BEAC_NAME, T_ADMIN_CONTACT and T_{ASM,SSM}_STATS.
T_ASM_STATS and T_SSM_STATS have the same format, only different types:
-------------------------
| 0 | 1 | 2 | 3 |
-------------------------
| lasttimestamp |
-------------------------
| age |
-------------------------
| TTL | avgdelay |
-------------------------
| ... | avgjitter |
-------------------------
| ... | loss| dup | ooo |
-------------------------
avgdelay and avgjitter are encoded using IEEE 754 single floating point format.
loss, dup and ooo have values between 0 and 255.
|
