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370 C
HAPTER
16: IP R
OUTING
Configure IP VLANs If you want to use IP routing, you must first configure the VLAN to use IP.
An IP VLAN is called a
protocol-based VLAN .
Protocol-based VLANs such as IP VLANs group one or more switch ports
together for one or more specified Layer 3 protocols. You can also create
network-based VLANs, which are IP VLANs that are grouped according to
the IP network address and mask.
When you use allClosed VLAN mode on a Multilayer Switching Module in
your system, you can enable the module to ignore Spanning Tree Protocol
(STP) mode on a per-VLAN basis; that is, ignore STP blocked ports. (When
STP detects multiple paths to a destination, it blocks all but one of the
paths.) You can use Ignore STP mode to avoid disruptions to routing
connectivity, based on the STP state.
See Chapter 14 in this guide to learn about VLANs.
Establish Your IP
Interfaces
To establish an IP interface:
1 Determine your interface parameters.
2 Define the IP interfaces.
Interface Parameters
Each IP routing interface has these standard characteristics:
■
IP address — An address from the range of addresses that the
Internet Engineering Task Force (IETF) assigns to your organization.
This address is specific to your network and Multilayer Switching
Module.
■
Subnet mask — The 32-bit number that uses the same format and
representation as an IP address. The subnet mask determines which
bits in the IP address are interpreted as the network
number/subnetwork number and the host number. Each IP address bit
that corresponds to a 1 in the subnet mask is in the
network/subnetwork part of the address. Each IP address bit that
corresponds to a 0 is in the host part of the IP address.
■
State — The status of the IP interface. It indicates whether the
interface is available for communications (
up
) or unavailable (
down
).
■
VLAN interface index (for in-band management) — The number
of the IP VLAN that is associated with the IP interface. When the