Allied Telesis AT-S63, Features Manual

Page: 326 / 538

Chapter 29: Internet Protocol Version 4 Packet Routing
326 Section VII: Routing
Routing Interfaces
The IPv4 packet routing feature on the switch is built on the foundation of
the routing interface. An interface functions as a logical connection to a
subnet that allows the egress and ingress of IPv4 packets to the subnet
from other local and remote networks, subnets, and nodes.
Interfaces are an independent routing function. They are not dependent on
static routes or RIP to pass IPv4 traffic among themselves on a switch. A
switch automatically begins to route IPv4 packets among its local subnets
as soon as two or more interfaces have been defined on the device.
In order for a switch to route IPv4 traffic among it local subnets, it must
have a routing interface on each subnet. You create an interface by
assigning it a unique IP address of the subnet and indicating the VLAN
where the subnet resides.
Interfaces also function as anchor points for static routes. A static route
defines the next hop to a remote destination. To create a static route to a
remote destination, you add it to the interface on the switch where the next
hop to the remote destination is located.
Interfaces also act as anchor points for RIP. You can add RIP to the
interfaces so that the switch automatically learns routes to remote
destinations by sharing its routing information with the neighboring
routers.
In some limited network topologies, you might be able to meet the routing
requirements of the IPv4 packets of your network with just routing
interfaces. This would assume, of course, that the switch is directly
connected to all of the networks or subnets of your network and that there
are no remote destinations that would require static routes or RIP.
Here are several other items to note concerning routing interfaces on the
AT-9400 Switch:
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The switch can support up to 512 interfaces at one time, which means
it can route the IPv4 traffic on up to 512 local subnets and networks.
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A single VLAN on a switch can contain up to sixteen interfaces.
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The AT-9408LC/SP, AT-9424T/GB, and AT-9424T/SP switches do not
support the IPv4 packet routing feature. However, you can create one
routing interface on the switches to serve as an IP configuration for the
device. For more information, refer to “Routing Interfaces and
Management Features” on page 342 and “AT-9408LC/SP AT-9424T/
GB, and AT-9424T/SP Switches” on page 346.
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The commands for managing interfaces are ADD IP INTERFACE,
DELETE IP INTERFACE, and SET IP INTERFACE.