Understanding Access Vlans; Understanding The Native Vlan Id For Trunk Ports - Cisco nexus 5000 series Cli Configuration Manual

Chapter 1 Configuring Access and Trunk Interfaces
S e n d f e e d b a c k t o n x 5 0 0 0 - d o c f e e d b a c k @ c i s c o . c o m
Figure 1-2 Header without and with 802.1Q Tag Included
Preamble
(7 - bytes)
Preamble
(7-bytes)

Understanding Access VLANs

Note If you assign an access VLAN that is also a primary VLAN for a private VLAN, all access ports with
that access VLAN will also receive all the broadcast traffic for the primary VLAN in the private VLAN
mode.
When you configure a port in access mode, you can specify which VLAN will carry the traffic for that
interface. If you do not configure the VLAN for a port in access mode, or an access port, the interface
carries traffic for the default VLAN (VLAN1).
You can change the access port membership in a VLAN by specifying the new VLAN. You must create
the VLAN before you can assign it as an access VLAN for an access port. If you change the access
VLAN on an access port to a VLAN that is not yet created, the system will shut that access port down.
If an access port receives a packet with an 802.1Q tag in the header other than the access VLAN value,
that port drops the packet without learning its MAC source address.

Understanding the Native VLAN ID for Trunk Ports

Native VLAN ID numbers must match on both ends of the trunk.
Note
OL-16597-01
Dest.
Start
MAC
Frame
Address
Delimiter
(6 -
(1 - byte)
bytes)
Dest. Source
Start
MAC MAC
Frame
Address Address
Delimiter
(6-bytes) (6-bytes)
(1-byte)
Source
Length
MAC
/ Type MAC Client Data
Address
(2 -
(6 -
bytes)
bytes)
Length/Type Tag
= 802.1Q Control
Tag Type Information
(2-byte) (2-bytes)
3 bits = User Priority field
1 bit = Canonical Format Identifier (CFI)
12 bits – VLAN Identifier (VLAN ID)
Cisco Nexus 5000 Series Switch CLI Software Configuration Guide
Information About Access and Trunk Interfaces
Pad
(0 - p
(0 - n bytes)
bytes)
Length
MAC Client
/Type
Data
(2-
(0-n bytes) bytes)
bytes)
Frame
Check
Sequence
(4 - bytes)
Frame
Pad
Check
(0-p
Sequence
(4-bytes)
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