Allied Telesis AT-S63 - Manual (Page 82)

Chapter 3: Enhanced Stacking
82 Section I: Basic Operations
Master Switch and the Local Interface
Before a switch can function as the master switch of an enhanced stack, it
needs to know which subnet is acting as the common subnet among the
switches in the stack. It uses that information to know which subnet to
send out its broadcast packets and to monitor for the management
packets from the other switches and from remote management
workstations.
Designating the common VLAN and subnet involves creating a routing
interface on the master switch on the common subnet and designating it
as the local interface. The concept of routing interfaces first appeared in
the AT-9400 Switch with Layer 3 routing and the implementation of static
routing and the Routing Information Protocol (RIP) version 1 and 2.
An interface represents a logical connection to a network or subnet local to
the switch for purposes of routing packets. To configure an interface, you
assign it an IP address and subnet mask appropriate to the subnet where
it will route packets, and add it to the VLAN that contains the subnet.
For the most part, routing interfaces are limited to the IPv4 packet routing
feature and are unnecessary beyond that feature. There are, however, a
few exceptions. One is the enhanced stacking feature. The rule is that the
master switch of an enhanced stack must have at least one interface and
the interface must be assigned to the common subnet that interconnects
the switches of the stack. Furthermore, the interface must be designated
as the switch’s local interface. The act of designating an interface as the
local interface tells the switch which interface and which subnet it should
use for the enhanced stacking feature.
For background information on the IPv4 routing feature, refer Chapter 29,
“Internet Protocol Version 4 Packet Routing” on page 321.