Cabletron Systems 04-0053-01 User Manual

2-8   SmartSwitch ATM User Guide

Creating an Emulated LAN

  IP Over ATM and LANE

The 

 address is constructed from:

netprefix + chassis MAC address + selector byte of 01

For example

netprefix = 

39:00:00:00:00:00:00:00:00:00:A3:87:0B

chassis MAC address = 

00:00:1D:A3:87:0B

then,

default LECS address = 

39:00:00:00:00:00:00:00:00:00:A3:87:0B:00:00:1D:A3:87:0B:01

The 

 and 

 have the same ATM address. LES and BUS addresses are constructed from:

netprefix + chassis MAC address + ELAN number summed with the numerical value two (2)

For example

netprefix = 

39:00:00:00:00:00:00:00:00:00:A3:87:0B

chassis MAC address = 

00:00:1D:A3:87:0B

ELAN number = 

3

then,

default LES and BUS addresses = 

39:00:00:00:00:00:00:00:00:00:00:00:1D:A3:87:0B:05

2.2.2

ELANs Across Multiple Switches

ELANs can exist within a single switch, or they can span multiple switches. When an ELAN spans multiple switches, 
it’s important that all switches within the group use the same LECS (see note, below). The general rule is: “Within an 
administrative domain (a group of switches with related ELANs), there should be one and only one LECS.” For this 
reason, never start the LECS on more than one switch within the administrative domain. 

The exception to the statement above is that if LNNI is enabled, multiple, 
redundant LECS’ and LES/BUS’ can exist within the same administrative 
domain. See Section 2.2.7 “Using LNNI.”

If an uplink, end node, or other ATM switch does not support PNNI, or if its 
version of ILMI is incompatible, it may be necessary to set up a static route 
between the device and the rest of the ELAN. See Chapter 4, "Routing."