Cisco WS-X6416-GE-MT - Interface Module - Expansion Instrukcja Użytkownika Pobierz pdf (Strona 19)

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The VLAN ID configuration creates an instance of a Layer 2 broadcast domain or VLAN. The

configuration is done from global configuration mode using a vlan <vlan #> command. VLAN IDs

from 1 through 4094 are supported, where VLAN IDs 1002 to 1005 are VTP default VLANs in both

the Cisco Catalyst OS and Cisco IOS Software and are not user configurable.

The following example demonstrates the creation of vlan 8 in the Cisco Catalyst OS and Cisco IOS

Software:

Cisco Catalyst OS Cisco IOS Software

set vlan 8 IOS#configure terminal

IOS(config)#vlan 8

IOS(config-vlan)#exit

Because the Cisco Catalyst OS and Cisco IOS Software support the creation of 4094 Layer 2

VLANs, a MAC-address reduction feature must be enabled so that the system can allocate a

limited number of system MAC addresses more efficiently. The following commands enable this

feature:

Cisco Catalyst OS Cisco IOS Software

set spantree macreduction enable IOS(config)# spanning-tree extend system-id

Routed SVI

When multiple ports on the same device belong to a single subnet, a VLAN is created to group

these ports at Layer 2 (see Layer 2 VLAN, above). Generally, these ports need to send traffic to

other subnets or VLANs. This requirement is accomplished by creating an SVI to provide the inter-

VLAN routing functionality. Just as in the hybrid software model, SVIs in Cisco IOS Software are

identified as interface VLAN 1, interface VLAN 2, and so on. These interfaces are associated

with Layer 3 information such as an IP subnet or IPX network number. If a particular Layer 2 VLAN

does not have an associated SVI created, then traffic will be bridged in that VLAN but is not

routable to or from that VLAN. As switch ports are added to and removed from various VLANs,

they automatically participate in the Layer 3 environment created by the appropriate SVI. For

managing a device in Cisco IOS Software, the SVI requires an IP address for network reachability.

Access Switchport

An access switchport is a Layer 2 port that belongs to only one VLAN. For configuration, the

switchport command is used to convert an interface from the default routed interface to a Layer 2

interface. In converting the port from a Layer 3 port to a Layer 2 port, Layer 2 features, such as

DTP and Spanning Tree Protocol, are enabled. This single switchport command must be

enabled before any other switchport-related configuration is allowed. Like port operation in the

Cisco Catalyst OS, Cisco IOS Software switchports automatically default to VLAN 1. To statically

create an access port (one that will not attempt to negotiate a trunk), enter the switchport mode

access command from the interface configuration. Then use the switchport access vlan <vlan-

id> command to assign the access port to a particular VLAN. The following example defines port

5/1 as an access port in VLAN2:

IOS# configure terminal

IOS(Config)# interface fastethernet5/1

IOS(Config-if)# switchport

IOS(Config-if)# switchport mode access

1 2 ... 14 15 16 17 18 19 20 21 22 23 24 ... 50 51

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