ANNEX B

(to Recommendation G.771)

LCN physical configuration attributes

These LCN physical configuration attributes represent the requirements an administration imposes on the configuration of the whole of the particular LCN to be designed. In the PQ(lcn) protocol suite selection process (§ 5.3.2) these LCN physical configuration attributes will not only influence the choice of PQ(lcn) protocol suite, but also determine the type and quantity of mediation devices needed.

During the design of the LCN the administration may also consider the number of ports per configuration and the number of such configurations that can be served by a particular mediation device that implements the selected protocol suite.

Together with the distribution of network elements over space and the cascadibility of the mediation devices this leads to the layout of the LCN.

However, such mediation device design characteristics are beyond the scope of this Recommendation.

Some LCN physical configuration attributes are:

1.	Number of NE ports

Specifies how many network element local communication ports are to be served by an LCN (including mediation devices).

Descriptor: (ports) small < 32

medium > 32, < 256

large > 256, < 2048

very large > 2048

2.	Configuration

Specifies the configuration to be used for the LCN.

Descriptor: star;

bus;

ring.

3.	Number of ports per configuration

Specifies how many ports are to be interconnected within a single configuration (star, bus or ring) of the LCN.

For a star configuration count the number of branches, as one port per branch is implicitly assumed. For master-slave protocol suites for the bus or ring configuration, the master is excluded from the count of ports per configuration.

Descriptor: (ports) small < 8

medium > 8, < 32

large > 32, < 128

very large > 128

4.	Communication distance

Specifies the distance to be bridged within the LCN.

Descriptor: (meters) very short < 10

short > 10, < 100

medium > 100, < 1000

long > 1000

5.	Communication environment

Descriptor: within-rack

on the same floor

in-building

out of building

The need to provide further attributes is for further study.

ANNEX E

(to Recommendation G.771)

LCN protocol selection attributes

These LCN protocol selection attributes summarise the capabilities of the individual PQ(lcn) protocol suites for use in the LCN protocol suite selection process described in § 5.3.2.

Note - Abbreviations are given for each allowed attribute value as a key to Table F.5/G.771.

The protocol selection attributes are:

At layer 1:

configuration S: star; B: bus; R: ring

number of ports per S: small < 8

configuration (ports) M: medium > 8, < 32

L: large > 32, < 128

VL: very large > 128

physical medium SP: screened pair; TP: twisted pair CP: coaxial pair; OF: optical fiber

O: other

transmission mode S: synchronous; AS: asynchronous; HD: half duplex; FD: full duplex

operating speed 1200, 2400, 4800, 9600, 19200,

(bits per second) 64000, 128 000, 1 000 000

communication distance VS: very short < 10

(meters) S: short > 10 < 100

M: medium > 100, < 1000

L: long > 1000

communication environment WR: within-rack; OF: on the

same floor;

IB: in-building; OB: out of building

availability (%) L: low

M: medium under study

H: high

At layer 2:

data link connection CO: connection oriented;

CL: connection less.

data link initiator M: master; AP: all participants

data link address size S: small < 8

(addresses) M: medium > 8, < 32

L: large > 32, < 128

VL: very large > 128

receipt confirmation Y: yes; N: no

maximum frame size S: small < 256

(octets) M: medium > 256, < 4096

L: large > 4096

max: frame frequency per L: low < 1/60

port (frames per second) M: medium > 1/60, < 1

H: high > 1

max: frame transmit delay S: short < 0.1

(seconds) M: medium > 0.1 < 1

L: long > 1

error detection N: none; P: parity; CS: checksum (n)	CRC: cyclic redundancy check (n)

hamming distance 1, 2, 3, 4, n

error recovery N: none; R: repetition;

C: correction

At layer 3:

LCN network size S: small < 32

(ports) M: medium > 32, < 256

L: large > 256 < 2048

VL: very large > 2048

routing Y: yes; N: no

(un) packing Y: yes; N: no

connections N: none; P: permanent; SW: switched

priority Y: yes; N: no

The other layers are for further study.