Avaya Configuring Ethernet, FDDI, and Token Ring Services Instrukcja Użytkownika Pobierz pdf (Strona 75)

Configuring 802.1Q Tagging

305259-A Rev 00

5-3

• A VLAN contains broadcast traffic within software-defined boundaries.

With reference to Figure 5-1

, broadcast traffic within the bridged topology is

propagated across all physical interfaces. For example, a broadcast frame

originated by a workstation on LAN segment 1 is forwarded to LAN segments

2, 3, and 4. In contrast, within the VLAN topology, a broadcast frame

originated by a workstation on LAN segment 1 is forwarded only to LAN

segment 2. Broadcast traffic is confined with the bounds of the VLAN.

• A VLAN provides low-latency, wire-speed communication between VLAN

members.

All members of the Engineering VLAN, for example, communicate at wire

speed whether they are physically connected to LAN segment 1 or 2.

• A VLAN supports network segmentation or microsegmentation; a VLAN

segment can consist of one or many workstations.

• A VLAN is a closed bridge group, with boundaries enforced by spanning tree

protocols.

• Intra-VLAN communication is provided by layer 2 switching.

• Inter-VLAN communication requires additional layer 3 services. Layer 3

services may be provided by the VLAN device or by an adjacent router.

Intra-VLAN Traffic Flow

Intra-VLAN traffic (where the frame source and the frame destination are both on

the same VLAN) is forwarded at layer 2 by the VLAN device. Forwarding

decisions are based on layer 2 forwarding tables that associate specific MAC/layer

2 addresses with specific device ports.

Inter-VLAN Traffic Flow

Inter-VLAN traffic (where the frame source and the frame destination are not on

the same VLAN) requires layer 3 (routing) services. Certain advanced platforms

(such as the Accelar family of routing switches) can provide these services.

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Avaya Configuring Ethernet, FDDI, and Token Ring Services Instrukcja Użytkownika Strona 75