THOMSON R7.4 Configuration Manual
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VLAN Configuration Guide
R7.4 and higher
Thomson Gateway
Thomson Gateway
VLAN Configuration Guide
R7.4 and higher
Copyright
Copyright ©1999-2008 Thomson. All rights reserved.
Distribution and copying of this document, use and communication of its contents is not permitted without written authorization
from Thomson. The content of this document is furnished for informational use only, may be subject to change without notice,
and should not be construed as a commitment by Thomson. Thomson assumes no responsibility or liability for any errors or
inaccuracies that may appear in this document.
Thomson Telecom Belgium
Prins Boudewijnlaan, 47
B-2650 Edegem
Belgium
http://www.thomson-broadband.com
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Document Information
Status: v1.0 (March 2008)
Reference: E-DOC-CTC-20080229-0001
Short Title: Config Guide: VLAN R7.4 and higher
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Contents
About this VLAN Configuration Guide ..................................... 1
1 Introduction..................................................................................3
2 VLAN Overview ........................................................................... 5
3 Creating VLANs on the Thomson Gateway.............................. 9
4 Ethernet Bridge and VLANs......................................................11
4.1 VLAN Learning Constraints........................................................................... 12
4.2 Static Entries with VLANs ............................................................................ 14
4.3 VLAN Awareness .......................................................................................... 16
4.4 Port VLAN Membership ................................................................................ 17
4.5 Optional Incoming Traffic Validation............................................................ 20
4.6 Dynamic VLAN Membership ......................................................................... 22
4.7 Unknown VID Policy ..................................................................................... 25
4.8 Extra Tagging (Stacked VLANs) .................................................................... 28
5 Logical Ethernet Interfaces and VLANs................................... 33
5.1 WAN-side VLAN Tagging............................................................................... 34
5.2 VLAN Routing on the Thomson Gateway...................................................... 35
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Contents
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About this VLAN Configuration Guide
About this VLAN Configuration Guide
Used Symbols
Terminology
Generally, the Thomson Gateway356 will be referred to as Wireless USB Adaptor in this VLAN Configuration
Guide.
Typographical Conventions
Following typographical convention is used throughout this manual:
Sample text indicates a hyperlink to a Web site.
Example: For more information, visit us at www.thomson-broadband.com
.
Sample text indicates an internal cross-reference.
Example: If you want to know more about guide, see “1 Introduction” on page 7”.
Sample text indicates an important content-related word.
Example: To enter the network, you must authenticate yourself.
Sample text indicates a GUI element (commands on menus and buttons, dialog box elements, file
names, paths and folders).
Example: On the File menu, click Open to open a file.
Documentation and software updates
Thomson continuously develops new solutions, but is also committed to improving its existing products.
For more information on Thomson's latest technological innovations, documents and software releases, visit
us at http://www.thomson-broadband.com
.
A note provides additional information about a topic.
A caution warns you about potential problems or specific precautions that need to be taken.
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About this VLAN Con
figuration Guide
Overview
First, this VLAN Configuration Guide shortly lists the VLAN features of the Thomson Gateway and the
relevant standards. Some background information on several VLAN-related concepts is also provided. Next,
this document describes the configuration of each VLAN feature on the Thomson Gateway in detail. CLI
(Command Line Interface) commands are used for the configuration.
This document is structured as follows:
Topi c Page
“1 Introduction” 3
“2 VLAN Overview” 5
“3 Creating VLANs on the Thomson Gateway” 9
“4 Ethernet Bridge and VLANs” 11
“5 Logical Ethernet Interfaces and VLANs” 33
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1| Introduction
1 Introduction
Introduction
Virtual Local Area Networks, commonly known as VLANs, are the subject of this document. In this chapter,
we shortly list the VLAN features that are supported by the Thomson Gateway, the relevant standards and
related documents.
Supported VLAN features
Thomson Gateway devices support following VLAN features:
Creation of VLANs on the Thomson Gateway
VLAN features of the Ethernet bridge
VLAN learning constraints for dynamic entries
Creation of static entries with VLANs
VLAN awareness of the bridge
Tagged and untagged VLAN membership of bridge ports
Port VID of a bridge port
Acceptance of only VLAN-tagged frames
Ingress filtering of VLAN-tagged frames
Dynamic VLAN membership
Unknown VID policy
Extra tagging (stacked VLANs)
VLAN features of the logical Ethernet interfaces
WAN-side VLAN tagging
Support of VLAN routing on the Thomson Gateway
Standards compliancy
Thomson Gateway devices are compliant with following standards, which are relevant to Ethernet, Ethernet
bridging, VLAN bridging, VLAN user priorities and stacked VLANs:
IEEE Std 802.3 - 2000: Part 3: Carrier sense multiple access with collision detection (CSMA/CD) access
method and physical layer specifications.
IEEE Std 802.1D - 2004: IEEE standard for local and metropolitan area networks - Media Access Control
(MAC) bridges.
IEEE Std 802.1Q - 1998: IEEE standard for local and metropolitan area networks - Virtual bridged local
area networks.
IEEE Std 802.1p: Traffic Class Expediting and Dynamic Multicast Filtering. This standard is merged into
802.1D-2004.
IEEE Std 802.1ad - 2005: IEEE standard for local and metropolitan area networks - Virtual bridged local
area networks - Amendment 4: Provider bridges.
Related documents
Other Layer 2 related features, such as Ethernet and Ethernet QoS, are described in other documents. See the
“Ethernet Configuration Guide” and the “Ethernet QoS Configuration Guide” for more information.
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1| Introduction
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2| VLAN Overview
2 VLAN Overview
What is a VLAN?
A VLAN is a Layer 2 method of creating independent logical networks within a single physical network. Hosts
in the same VLAN behave as if they are connected to the same LAN segment, even though they may be
physically connected to different LAN segments.
The primary use of VLANs is to split large switched networks, which are large broadcast domains. While
traditional LAN segmentation adds routers to the network to split a broadcast domain, VLAN segmentation
adds VLAN-aware switches. Routers are only needed to communicate between two VLANs.
Following illustration shows the difference between traditional physical LAN segmentation and logical VLAN
segmentation:
Advantages of using VLANs
The use of VLANs is very popular in today’s networks, because VLANs offer several advantages:
Increased performance:
VLANs increase the number of broadcast domains but reduce the size of each broadcast domain. As
this limits broadcast storms, multicast traffic, chatty protocols and so on, overall network traffic is
reduced.
VLAN-aware switches add no substantial latency compared to routers, as the amount of routing
(Layer 3 forwarding) is reduced.
Snooping is limited, which increases the network security.
Router
VLAN1 VLAN2
VLAN3
VLAN Switch
VLAN Switch
VLAN Switch
LAN3
Hub
Router
LAN1
Hub
LAN2
Hub
Traditional LAN segmentation VLAN segmentation
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2| VLAN Overview
Topological independence: the use of VLANs allows non-physical grouping of nodes that share similar
resources. This results in the creation of logical networks, independent of the physical location of the
involved nodes. Hardware requirements are reduced, as networks can be separated logically instead of
physically.
Ease of administration: the management efforts to create (logical) networks are reduced:
Nodes can easily change their VLAN membership.
Network topology changes, for example a host moving to another location, no longer require
hardware changes but can be done via software.
Cost-effectiveness is improved: less routers, which are costly, are needed and VLAN-aware switches are
used instead. Routers are only needed to communicate between two VLANs.
Additional features: the VLAN user priority allows Layer 2 traffic separation.
VLAN-tagged frame format
In order to support VLANs, the Ethernet frame format is extended with a VLAN tag, indicated in red in the
following illustration:
A VLAN tag consists of following fields:
Tag Protocol Identifier (TPID): this field is located at the same place as the Length/Type field of untagged
frames. The value of the field is always equal to 0x8100, which indicates that the frame is tagged and that
the original Length/Type field is located after the VLAN tag.
Tag Control Information (TCI):
User Priority Field: this field indicates the 802.1p user priority.
Canonical Format Indicator (CFI)
VLAN Identifier (VID): this field identifies the VLAN to which the frame belongs.
Destination
MAC Address
Source
MAC Address
Length/
Type
TPID TCI
FCS
662 422
PadData/LLC
0 .. 1500 46 .. 0 bytes
Min. 46 bytes - Max. 1500 bytes
Min. 68 bytes - Max. 1522 bytes
Priority CFI VID
3 1 12 bits
VLAN tag
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2| VLAN Overview
Stacked VLAN frame format
VLAN stacking means that a frame contains two VLAN tags. An example of a stacked VLAN frame format is
shown in the following illustration:
An S-tag can be distinguished from a C-tag as follows:
The value of the TPID field of an S-tag is set to 0x88a8.
An S-tag contains a DEI (Drop Eligible Indicator) field instead of a CFI field.
Destination
MAC Address
Source
MAC Address
Length/
Type
TPID TCI
FCS
662 422
PadData/LLC
0 .. 1500 46 .. 0 bytes
Min. 46 bytes - Max. 1500 bytes
Min. 72 bytes - Max. 1526 bytes
TPID TCI
22
Customer
VLAN tag
= C-tag
Service Provider
VLAN tag
= S-tag
Priority DEI VID
3 1 12 bits
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2| VLAN Overview
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