|A value which indicates the set of services that this
entity may potentially offer. The value is a sum.
This sum initially takes the value zero. Then, for
each layer, L, in the range 1 through 7, that this node
performs transactions for, 2 raised to (L - 1) is added
to the sum. For example, a node which performs only
routing functions would have a value of 4 (2^(3-1)).
In contrast, a node which is a host offering application
services would have a value of 72 (2^(4-1) + 2^(7-1)).
Note that in the context of the Internet suite of
protocols, values should be calculated accordingly:
1 physical (e.g., repeaters)
2 datalink/subnetwork (e.g., bridges)
3 internet (e.g., supports the IP)
4 end-to-end (e.g., supports the TCP)
7 applications (e.g., supports the SMTP)
For systems including OSI protocols, layers 5 and 6
may also be counted.