
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.
Comentarios a estos manuales