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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
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Chapter 13 Configuring Interface Characteristics Interface Types
The number of routed ports that you can configure is not limited by software. However, the
interrelationship between this number and the number of other features being configured might impact
CPU performance because of hardware limitations. See the “Configuring Layer 3 Interfaces” section on
page 13-37 for information about what happens when hardware resource limitations are reached.
For more information about IP unicast and multicast routing and routing protocols, see Chapter 42,
“Configuring IP Unicast Routing” and Chapter 48, “Configuring IP Multicast Routing.”
Note The IP base feature set supports static routing and the Routing Information Protocol (RIP). For full
Layer 3 routing or for fallback bridging, you must enable the IP services feature set on the standalone
switch, or the stack master.
Switch Virtual Interfaces
A switch virtual interface (SVI) represents a VLAN of switch ports as one interface to the routing or
bridging function in the system. Only one SVI can be associated with a VLAN, but you need to configure
an SVI for a VLAN only when you wish to route between VLANs, to fallback-bridge nonroutable
protocols between VLANs, or to provide IP host connectivity to the switch. By default, an SVI is created
for the default VLAN (VLAN 1) to permit remote switch administration. Additional SVIs must be
explicitly configured.
Note You cannot delete interface VLAN 1.
SVIs provide IP host connectivity only to the system; in Layer 3 mode, you can configure routing across
SVIs.
Note Layer 3 mode is not supported on switches running the LAN base feature set.
Although the switch stack or switch supports a total of 1005 VLANs (and SVIs), the interrelationship
between the number of SVIs and routed ports and the number of other features being configured might
impact CPU performance because of hardware limitations. See the “Configuring Layer 3 Interfaces”
section on page 13-37 for information about what happens when hardware resource limitations are
reached.
SVIs are created the first time that you enter the vlan interface configuration command for a VLAN
interface. The VLAN corresponds to the VLAN tag associated with data frames on an ISL or
IEEE 802.1Q encapsulated trunk or the VLAN ID configured for an access port. Configure a VLAN
interface for each VLAN for which you want to route traffic, and assign it an IP address. For more
information, see the “Manually Assigning IP Information” section on page 3-15.
Note When you create an SVI, it does not become active until it is associated with a physical port.
SVIs support routing protocols and bridging configurations. For more information about configuring IP
routing, see Chapter 42, “Configuring IP Unicast Routing,” Chapter 48, “Configuring IP Multicast
Routing,”and Chapter 50, “Configuring Fallback Bridging.”