RADIUS attribute from rfc2866
Acct-Link-Count
This attribute gives the count of links which are known to have been
in a given multilink session at the time the accounting record is
generated. The NAS MAY include the Acct-Link-Count attribute in any
Accounting-Request which might have multiple links.
A summary of the Acct-Link-Count attribute format is show below. The
fields are transmitted from left to right.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Value
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Value (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+Type
51 for Acct-Link-Count.
Length
6
Value
The Value field is four octets, and contains the number of links
seen so far in this Multilink Session.
It may be used to make it easier for an accounting server to know
when it has all the records for a given Multilink session. When
the number of Accounting-Requests received with Acct-Status-Type =
Stop and the same Acct-Multi-Session-Id and unique Acct-Session-
Id's equals the largest value of Acct-Link-Count seen in those
Accounting-Requests, all Stop Accounting-Requests for that
Multilink Session have been received.
An example showing 8 Accounting-Requests should make things
clearer. For clarity only the relevant attributes are shown, but
additional attributes containing accounting information will also
be present in the Accounting-Request.
Multi-Session-Id Session-Id Status-Type Link-Count
"10" "10" Start 1
"10" "11" Start 2
"10" "11" Stop 2
"10" "12" Start 3
"10" "13" Start 4
"10" "12" Stop 4
"10" "13" Stop 4
"10" "10" Stop 4