Cabletron Systems 04-0053-01 manual Lnni call set up load sharing

Creating an Emulated LAN

IP Over ATM and LANE

1

SW1

SW2

		LES/BUS
	CLIENT
		(LNNI)
Client attempts ELAN
join through switch SW1.

SW1

2

CLIENT	LES/BUS
	(LNNI)

3 SW1

CLIENT	LES/BUS
	(LNNI)
Client now uses
SW1 for its call
setups.

LECS (LNNI)

SW2
Netprefix	LECS checks SW1's
of SW1?	netprefix. Is it known
	to contain an LES/BUS,
LECS	and is it participating
	in LNNI?
(LNNI)
SW2
	If yes, tell client
	to use SW1 as its
	LES/BUS.
LECS	If no, client is assigned
	to a switch with an
(LNNI)	LES/BUS on a round-
	robin basis.

Figure 2-4 LNNI call set up load sharing

Additional load sharing can be achieved using LNNI and distributed LANE services. Using distributed LANE, LNNI allows each switch containing an LECS to support up to eight (8) LES/BUSs on eight other (separate) switches on the same ELAN. This allows for a possible 64 LES/BUSs supporting each ELAN.

When a client attempts an ELAN join, the LECS checks the netprefix of the switch through which the client is attempting to join. If the netprefix of the switch corresponds to a switch known to be participating in LNNI and containing an LES/BUS, the LECS assigns the client to the LES/BUS on its directly connected switch. This keeps the client’s call setups local to his directly attached switch, and allows other LES/BUSs (on other switches) free to service the call setups of their locally attached clients.

For example, In Figure 2-5,Clients A, B, and C are assigned to the LES/BUS of the switch to which each is physically attached. Client D’s switch is not running an LES/BUS under LNNI, and is assigned to an LES/BUS on some other switch.

2-18 SmartSwitch ATM User Guide