Connecting Interfaces - Cisco Catalyst 2975 Software Configuration Manual

Understanding Interface Types

Connecting Interfaces

Devices within a single VLAN can communicate directly through any switch. Ports in different VLANs
cannot exchange data without going through a routing device.
In the configuration shown in
the data must go from Host A to the switch, to the router, back to the switch, and then to Host B.
Figure 12-1
With a standard Layer 2 switch, ports in different VLANs have to exchange information through a
router. By using the switch with routing enabled, when you configure both VLAN 20 and VLAN 30 with
an SVI to which an IP address is assigned, packets can be sent from Host A to Host B directly through
the switch with no need for an external router
Figure 12-2
172.20.128.1
Catalyst 2975 Switch Software Configuration Guide
12-10
Figure
Connecting VLANs with Layer 2 Switches
Host A
VLAN 20
Connecting VLANs with a Layer 3 Switch
with routing enabled
SVI 1
Host A
VLAN 20
12-1, when Host A in VLAN 20 sends data to Host B in VLAN 30,
Cisco router
Switch
Host B
VLAN 30
(Figure 12-2).
Layer 3 switch
SVI 2
VLAN 30
Chapter 12 Configuring Interface Characteristics
172.20.129.1
Host B
OL-19720-02