Steps For Configuring Routing - Cisco WS-C3550-12G Software Configuration Manual

Chapter 22 Configuring IP Unicast Routing
When Host A in VLAN 10 needs to communicate with Host B in VLAN 10, it sends a packet addressed
to that host. Switch A forwards the packet directly to Host B, without sending it to the router.
When Host A sends a packet to Host C in VLAN 20, Switch A forwards the packet to the router, which
receives the traffic on the VLAN 10 interface. The router checks the routing table, determines the correct
outgoing interface, and forwards the packet on the VLAN 20 interface to Switch B. Switch B receives
the packet and forwards it to Host C.

Steps for Configuring Routing

By default, IP routing is disabled on the Catalyst 3550 switch, and you must enable it before routing can
take place. For detailed IP routing configuration information, refer to the Cisco IOS IP and IP Routing
Configuration Guide for Release 12.1.
In the following procedures, the specified interface must be one of these Layer 3 interfaces:
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A Layer 3 switch can have an IP address assigned to each routed port and SVI. The number of routed
Note
ports and SVIs that you can configure is not limited by software. However, the interrelationship
between this number and the number and volume of features being implemented might have an
impact on CPU utilization because of hardware limitations. For more information about feature
combinations, see the
page
All Layer 3 interfaces must have IP addresses assigned to them. See the
Network Interfaces" section on page
Configuring routing consists of several main procedures:
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A routed port: a physical port configured as a Layer 3 port by using the no switchport interface
configuration command.
A switch virtual interface (SVI): a VLAN interface created by using the interface vlan vlan_id
global configuration command and by default a Layer 3 interface.
An EtherChannel port channel in Layer 3 mode: a port-channel logical interface created by using
the interface port-channel port-channel-number global configuration command and binding the
Ethernet interface into the channel group. For more information, see the
EtherChannels" section on page
"Optimizing System Resources for User-Selected Features" section on
6-57.
To support VLAN interfaces, create and configure VLANs on the switch, and assign VLAN
membership to Layer 2 interfaces. For more information, see
VLANs."
Configure Layer 3 interfaces.
Enable IP routing on the switch.
Assign IP addresses to the Layer 3 interfaces.
Enable selected routing protocols on the switch.
Configure routing protocol parameters (optional).
21-11.
22-5.
Catalyst 3550 Multilayer Switch Software Configuration Guide
Steps for Configuring Routing
"Configuring Layer 3
"Assigning IP Addresses to
Chapter 9, "Creating and Maintaining
22-3