Overview; Layer 2 Ethernet Switching Overview; Vlans; Chapter - Cisco nexus 5000 series Configuration Manual

Overview

This chapter contains the following sections:
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Layer 2 Ethernet Switching Overview

The device supports simultaneous, parallel connections between Layer 2 Ethernet segments. Switched
connections between Ethernet segments last only for the duration of the packet. New connections can be made
between different segments for the next packet.
The device assigns a domain (for example, a server) to each device to solve traffic congestion caused by
high-bandwidth devices and large number of users.
Because collisions cause significant congestion in Ethernet networks, an effective solution is full-duplex
communication. Typically, 10/100-Mbps Ethernet operates in half-duplex mode, which means that stations
can either receive or transmit. In full-duplex mode, which is configurable on these interfaces, two stations
can transmit and receive at the same time. When packets can flow in both directions simultaneously, the
effective Ethernet bandwidth doubles. 1/10-Gigabit Ethernet operates in full-duplex only.

VLANs

A VLAN is a switched network that is logically segmented by function, project team, or application, without
regard to the physical locations of the users. VLANs have the same attributes as physical LANs, but you can
group end stations even if they are not physically located on the same LAN segment.
Any switch port can belong to a VLAN, and unicast, broadcast, and multicast packets are forwarded and
flooded only to end stations in that VLAN. Each VLAN is considered as a logical network, and packets
destined for stations that do not belong to the VLAN must be forwarded through a bridge or a router.
All ports are assigned to the default VLAN (VLAN1) when the device comes up.
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Layer 2 Ethernet Switching Overview, page 3
VLANs, page 3
Private VLANs, page 4
Spanning Tree , page 4
Cisco Nexus 5000 Series NX-OS Layer 2 Switching Configuration Guide, Release 5.1(3)N1(1)
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