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 TableF.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.