Black Box LBG1000A User manual

JANUARY 2002
LBG1000A
LBG1001C
Managed Express Switch
Customer Support Information:
To order or for technical support: Call 724-746-5500 or fax [phone]
Technical support and fax orders 24 hours a day 7 days a week
Phone orders 24 hours, 7 A.M. Monday to midnight Friday; Saturday 8 to 4 (Eastern)
Mail order: Black Box Corporation 1000 Park Drive Lawrence PA 15055-1018
Web site: http://www.blackbox.com · E-mail: info blackbox.

FEDERAL COMMUNICATIONS COMMISSION AND
CANADIAN DEPARTMENT OF COMMUNICATIONS
RADIO FREQUENCY INTERFERENCE STATEMENT
Class B Digital Device. This equipment has been tested and found to comply with the limits for a Class B computing
device pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against
harmful interference in a residential installation. However there is no guarantee that interference will not occur in a
particular installation. This equipment generates uses and can radiate radio frequency energy and if not installed
and used in accordance with the instructions may cause harmful interference to radio communications. If this
equipment does cause harmful interference to radio or telephone reception which can be determined by turning the
equipment off and on the user is encouraged to try to correct the interference by one of the following measures:
• Reorient or relocate the receiving antenna.
• Increase the separation between the equipment and receiver.
• Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
• Consult an experienced radio/TV technician for help.
Caution:
Changes or modifications not expressly approved by the party responsible for compliance could void the user’s
authority to operate the equipment.
To meet FCC requirements shielded cables and power cords are required to connect this device to a personal
computer or other Class B certified device.
This digital apparatus does not exceed the Class B limits for radio noise emission from digital apparatus set out in
the Radio Interference Regulation of the Canadian Department of Communications.
Le présent appareil numérique n’émet pas de bruits radioélectriques dépassant les limites applicables aux appareils
numériques de la classe B prescrites dans le Règlement sur le brouillage radioélectrique publié par le ministère des
Communications du Canada.
Normas Oficiales Mexicanas (NOM)
INSTRUCCIONES DE SEGURIDAD
1. Todas las instrucciones de seguridad y operación deberán ser leídas antes de que el aparato
eléctrico sea operado.
2. Las instrucciones de seguridad y operación deberán ser guardadas para referencia futura.
3. Todas las advertencias en el aparato eléctrico y en sus instrucciones de operación deben ser
respetadas.
4. Todas las instrucciones de operación y uso deben ser seguidas.
5. El aparato eléctrico no deberá ser usado cerca del agua—por ejemplo cerca de la tina de baño
lavabo sótano mojado o cerca de una alberca etc.
6. El aparato eléctrico debe ser usado únicamente con carritos o pedestales que sean
recomendados por el fabricante.
7. El aparato eléctrico debe ser montado a la pared o al techo sólo como sea recomendado por el
fabricante.
8. Servicio—El usuario no debe intentar dar servicio al equipo eléctrico más allá a lo descrito en las
instrucciones de operación. Todo otro servicio deberá ser referido a personal de servicio calificado.
9. El aparato eléctrico debe ser situado de tal manera que su posición no interfiera su uso. La
colocación del aparato eléctrico sobre una cama sofá alfombra o superficie similar puede bloquea la ventilación no
se debe colocar en libreros o gabinetes que impidan el flujo de aire por los orificios de ventilación.
10. El equipo eléctrico deber ser situado fuera del alcance de fuentes de calor como radiadores
registros de calor estufas u otros aparatos (incluyendo amplificadores) que producen calor.
11. El aparato eléctrico deberá ser connectado a una fuente de poder sólo del tipo descrito en el
instructivo de operación o como se indique en el aparato.
12. Precaución debe ser tomada de tal manera que la tierra fisica y la polarización del equipo no sea
eliminada.
13. Los cables de la fuente de poder deben ser guiados de tal manera que no sean pisados ni
pellizcados por objetos colocados sobre o contra ellos poniendo particular atención a los contactos y receptáculos
donde salen del aparato.
14. El equipo eléctrico debe ser limpiado únicamente de acuerdo a las recomendaciones del
fabricante.
15. En caso de existir una antena externa deberá ser localizada lejos de las lineas de energia.
16. El cable de corriente deberá ser desconectado del cuando el equipo no sea usado por un largo
periodo de tiempo.
2

17. Cuidado debe ser tomado de tal manera que objectos liquidos no sean derramados sobre la
cubierta u orificios de ventilación.
18. Servicio por personal calificado deberá ser provisto cuando:
A: El cable de poder o el contacto ha sido dañado; u
B: Objectos han caído o líquido ha sido derramado dentro del aparato; o
C: El aparato ha sido expuesto a la lluvia; o
D: El aparato parece no operar normalmente o muestra un cambio en su desempeño; o
3

Preface
This manual describes how to install and use LBG1000A. This switch introduced here is designed to deliver full
scalability with SNMP/RMON web-based management functions by providing 24x10/100BASE-TX fixed ports
and optional 2x1000BASE-SX/LX ports. For the two Gigabit ports, it allows options of fiber type and wavelength
at user’s discretion. This switch brings a simple answer to today’s complicated networking environments.
To get the most out of this manual, you should have an understanding of Ethernet networking concepts.
In this manual, you will find:
Features on the switch
Illustrative LED functions
Installation instructions
Management Configuration
SNMP DHCP IGMP…
Specifications
4

Table of Contents2/25/02
PREFACE........................................................................................................................................... 4
TABLE OF CONTENTS2 25 02............................................................................................................. 5
PRODUCT OVERVIEW..........................................................................................................................7
LBG1000A MANAGEABLE 24 + 2 GIGABIT SWITCH............................................................................................................7
PACKAGE CONTENTS.........................................................................................................................................................7
PRODUCT HIGHLIGHTS ......................................................................................................................................................9
Basic Features...................................................................................................................................................................................................................................................9
Management Support........................................................................................................................................................................................................................................9
FRONT PANEL DISPLAY ...................................................................................................................................................11
PHYSICAL PORTS...........................................................................................................................................................13
BASIC FUNCTIONS..........................................................................................................................................................14
Unicast Switching............................................................................................................................................................................................................................................15
Multicast Switching..........................................................................................................................................................................................................................................15
VLAN........................................................................................................................................................................17
Broadcast Containment...................................................................................................................................................................................................................................18
Multicast-Based Multimedia Applications........................................................................................................................................................................................................18
nhanced Security..........................................................................................................................................................................................................................................18
VLAN Membership..........................................................................................................................................................................................................................................19
VLAN CONFIGURATION................................................................................................................................................................................................................................19
Intra-VLAN Communication.............................................................................................................................................................................................................................19
Inter-VLAN Communication.............................................................................................................................................................................................................................19
CLASS-OF-SERVICE (COS) SUPPORT.................................................................................................................................20
GVRP.......................................................................................................................................................................20
IGMP SNOOPING AND IP MULTICAST FILTERING...................................................................................................................21
SWITCH MANAGEMENT....................................................................................................................................................23
Administration console via RS-232 serial port................................................................................................................................................................................................23
Web-based browser interface.........................................................................................................................................................................................................................23
xternal SNMP-based network management application...............................................................................................................................................................................23
INSTALLATION..................................................................................................................................24
SELECTING A SITE FOR THE SWITCH...................................................................................................................................24
CONNECTING TO POWER..................................................................................................................................................25
Power-on Self test (POST)..............................................................................................................................................................................................................................26
CONNECTING TO YOUR NETWORK......................................................................................................................................27
Cable Type & Length.......................................................................................................................................................................................................................................27
Cabling.............................................................................................................................................................................................................................................................28
SWITCH MANAGEMENT.....................................................................................................................29
MANAGEMENT ACCESS OVERVIEW......................................................................................................................................30
ADMINISTRATION CONSOLE...............................................................................................................................................31
Direct Access...................................................................................................................................................................................................................................................31
Modem Access................................................................................................................................................................................................................................................32
WEB MANAGEMENT........................................................................................................................................................33
Netscape Navigator.........................................................................................................................................................................................................................................33
Internet xplorer..............................................................................................................................................................................................................................................33
SNMP-BASED NETWORK MANAGEMENT............................................................................................................................34
PROTOCOLS..................................................................................................................................................................35
MANAGEMENT ARCHITECTURE............................................................................................................................................35
MENU-DRIVEN CONSOLE MANAGEMENT........................................................................................... 36
LOGGING ON TO THE SWITCH.............................................................................................................................................36
At the screen prompt.......................................................................................................................................................................................................................................36
SWITCH MANAGEMENT SCREEN.........................................................................................................................................37
Navigating Through the Console Interface......................................................................................................................................................................................................37
PERFORMING BASIC MANAGEMENT ACTIVITIES......................................................................................................................38
Start with Selection Menu................................................................................................................................................................................................................................38
General Management Configurations.............................................................................................................................................................................................................39
LAN Port Configurations..................................................................................................................................................................................................................................40
Console Port Configurations...........................................................................................................................................................................................................................46
PERFORMING ADVANCED MANAGEMENT ACTIVITIES.................................................................................................................48
Start with Selection Menu................................................................................................................................................................................................................................48
L2 Switching DataBase...................................................................................................................................................................................................................................50
5

IP Networking..................................................................................................................................................................................................................................................60
Bridging............................................................................................................................................................................................................................................................69
Static Filtering..................................................................................................................................................................................................................................................72
Spanning Tree Functions.................................................................................................................................................................................................................................75
SNMP Functions..............................................................................................................................................................................................................................................80
Other Protocols................................................................................................................................................................................................................................................82
Port Trunking...................................................................................................................................................................................................................................................84
Port Mirroring...................................................................................................................................................................................................................................................86
Sending and Receiving Files...........................................................................................................................................................................................................................88
LOGOUT.......................................................................................................................................................................92
SAVE SETTINGS.............................................................................................................................................................92
RESTORE DEFAULT SETTINGS...........................................................................................................................................92
REBOOT.......................................................................................................................................................................92
WEB-BASED BROWSER MANAGEMENT.............................................................................................. 93
LOGGING ON TO THE SWITCH.............................................................................................................................................93
UNDERSTANDING THE BROWSER INTERFACE..........................................................................................................................94
PERFORMING FILE ACTIVITIES...........................................................................................................................................95
Start with Selection Menu................................................................................................................................................................................................................................95
PERFORMING BASIC SETUP ACTIVITIES................................................................................................................................97
Start with Selection Menu................................................................................................................................................................................................................................97
LAN Port Configuration...................................................................................................................................................................................................................................99
Console Port Configuration...........................................................................................................................................................................................................................101
PERFORMING ADVANCED SETUP ACTIVITIES........................................................................................................................103
Start with Selection Menu..............................................................................................................................................................................................................................103
MAC Address Management..........................................................................................................................................................................................................................104
IP Networking................................................................................................................................................................................................................................................108
Per Port Statistics..........................................................................................................................................................................................................................................117
Port Priority....................................................................................................................................................................................................................................................118
Bridging..........................................................................................................................................................................................................................................................119
Static MAC Filter............................................................................................................................................................................................................................................120
IP Multicast Group.........................................................................................................................................................................................................................................123
VLAN Perspective.........................................................................................................................................................................................................................................124
Spanning Tree Perspective...........................................................................................................................................................................................................................128
SNMP............................................................................................................................................................................................................................................................131
Other Protocols..............................................................................................................................................................................................................................................133
Port Trunking.................................................................................................................................................................................................................................................134
Port Mirroring.................................................................................................................................................................................................................................................135
SNMP & RMON MANAGEMENT................................................................................................. 136
OVERVIEW..................................................................................................................................................................136
SNMP AGENT AND MIB-2 (RFC 1213).......................................................................................................................137
RMON MIB (RFC 1757) AND BRIDGE MIB (RFC 1493).............................................................................................138
RMON Groups Supported.............................................................................................................................................................................................................................138
Bridge Groups Supported..............................................................................................................................................................................................................................139
SPECIFICATIONS............................................................................................................................. 140
APPENDIX A – CONNECTOR PINOUTS.............................................................................................. 142
6

Product Overview
LBG1000A Manageable 24 + 2 Gigabit Switch
Front View
Pac age Contents
When you unpack the product package, you shall find the items listed below. Please inspect the contents, and report
any apparent damage or missing items immediately to your authorized reseller.
This Manageable Switch
 User’s Manual
AC power cord
RS232 cable
Rackmount brackets with screws

Manageable Gigabit Switch
Product Highlights
Basic Features
High port count:
24x10/100BASE-TX ports with RJ-45 connectors
plus options of 2x1000BASE-SX/LX ports with SC connectors
Auto-negotiation for speed and duplexity on all TX ports
Full wire-speed forwarding rate
Store-and-forward mechanism
Back-pressure and IEEE 802.3x compliant flow control
Supports 2K MAC addresses
Provides 8M bit memory buffer
Provides one uplink button for port 24X
Front panel reset button
Front panel port status LEDs
♦Standard 19” rackmount size one-unit-height
Management Support
VLAN
Port-based VLAN up to eight groups
802.1Q tagged VLAN
TRUNKING
MAC-based Trunking up to four groups with a maximum of four ports each group
Load sharing based on source and destination MAC addresses
PORT-SECURITY
Limit number of MAC addresses learned per port
Static MAC addresses stay in the filtering table
PORT-MIRRORING
Port-mirroring provided through dedicated ports Port 1 & Port 13
User’s Manual

COS (IEEE802.1p Classification of Service)
4-level transmission priorities: 4 queues per output port
Packet transmission scheduled using Weighted Round Robin (WRR)
User-defined weights
Classification of packet priority can be based on either a VLAN tag on packet or a user-definable port priority
INTERNETWORKING PROTOCOLS
Bridging:
802.1D Spanning Tree
802.1p/Q – GARP/GVRP
Routing:
RIP
RIP-2
DHCP-Relay
ICMP Router Discovery Message
IP Multicast:
IGMP Snooping
IP Multicast Packet Filtering
Maximum of 256 VLANs and IP multicast sessions
NETWORK MANAGEMENT METHODS
Console port access via RS-232 cable
Telnet remote access
SNMP agent:
MIB-2 (RFC1213)
Bridge MIB (RFC1493)
RMON MIB (RFC1757) – statistics history alarm and events
VLAN MIB (802.1Q/RFC2674)
Private MIB
Java applet-based MIB browser
Web browser support based on HTTP server and CGI parser
Kermit/TFTP software-upgrade capability

Front Panel Display
LNK/ACT
1 3 5 7 9 11 13 15
FDX/COL
RESET PWR
Ma n ag e ab le
G iga bit Sw itc h
2 4 6 8 10 12 14 16
LNK/ACT
FDX/COL
POWER
This LED comes on when the switch is properly connected to power and turned on.
Port Status LEDs
The LEDs are located at the left side of each section displaying status for each respective port. Please refer to the following table
for more details.
LED State Indication
LNK/ACT
On A valid network connection established.
LNK stands for LINK.
Flashing Transmitting or receiving data.
ACT stands for ACTIVITY.
FDX/COL
On Connection in full duplex mode.
FDX stands for FULL-DUPLEX.
Flashing Collision occurred.
COL stands for COLLISION.
Off Connection in half-duplex mode.

Gigabit Port Status LEDs
The LEDs are located at the left side of each Gigabit module displaying status for each respective port. Please refer to the
following table for more details.
LED State Indication
ACT
Flashing Transmitting or receiving data.
ACT stands for ACTIVITY.
Off No activity.
LNK On A valid network connection established.
LNK stands for LINK.
Off No connection.
Uplink button
The uplink button is located at the right side of port 24X on the switch. Connect port 24X to another switch or hub and depress the
button for the uplink function.

Physical Ports
The Manageable Gigabit LBG1000A Switch provides 24x10/100TX fixed ports and options of 2x1000SX/LX
ports.
CONNECTIVITY
- SC connectors on Gigabit ports
- RJ-45 connectors on TX ports
- One MDIX port for uplink
<Note> Refer to the table on page 27 for cabling requirements.
MODE SELECTION
• 10BASE-T full-duplex mode
• 10BASE-T half-duplex mode
• 100BASE-TX full-duplex mode
• 100BASE-TX half-duplex mode
• 1000BASE-SX/LX full-duplex mode
• Auto-negotiating mode
<Note>
i. Half-duplex mode uses back pressure flow control to prevent the receiving buffer from being overrun by data from a source
node.
ii. ull-duplex mode uses 802.3x flow control standard to prevent fast data traffic from overrunning slow data traffic.
iii. Auto-negotiating mode is in use after auto-negotiating with the other end of the link.
iv. Half-duplex mode is not allowed with Gigabit ports.

Basic Functions
In general, the LBG1000Aswitch is responsible for switching both VLAN tagged and untagged frames from a
receiving port to one or more transmitting ports. The switch performs multiple steps during the switching process:
VLAN CLASSIFICATION
LEARNING
FILTERING
FORWARDING
AGING
Below is additional information about tasks that the switch performs during unicast and multicast switching.

Unicast Switching
VLAN CLASSIFICATION
When the LBG1000A switch receives a frame it classifies the frame in one of two ways:
- If the frame is untagged the switch classifies the frame to an associated VLAN.
- If the frame is tagged the switch uses the tagged VLAN ID to identify the broadcasting domain of the frame.
LEARNING
After VLAN classification the switch checks the <source MAC address VLAN> pair in the switching database (SDB) to see
whether the <source MAC address VLAN> pair is known.
- If it is unknown the switch inserts the <source MAC address VLAN> into the SDB and learns the <source MAC address VLAN>.
- If it is known the switch checks the <source MAC address VLAN> for a mismatched port ID. If the port ID associated with the
<source MAC address VLAN> pair in the SDB is different than the receiving port the switch modifies the port ID in the SDB and
modifies its management database (MDB) accordingly.
FILTERING
After learning the address the switch checks:
- Whether the source port or destination port is in the forwarding state.
- Whether the source MAC address or destination MAC address is to be filtered.
- Whether the source port ID is the same as destination port ID.
If any of these conditions are met the switch drops the receiving. Otherwise it continues with the forwarding process described
below.
FORWARDING
During the forwarding process the switch checks whether the <destination MAC address VLAN> pair is unknown.
- If it is unknown the switch floods the receiving frame to all ports in the VLAN excluding the source port.
- If it is known the switch forwards the receiving frame to the port associated with the <destination MAC address VLAN> pair. At
the same time the switch ascertains the individual’s port’s VLAN tagging/untagging configuration and corresponding VLAN ID to
render the appropriate frame tagging when the frame is ready to be transmitted.
Multicast Switching
For multicast switching the LBG1000A switch checks whether the received frame is a BPDU. If a BPDU is received the
switch forwards the frame to the CPU for processing by the spanning tree protocol. Otherwise the switch performs the
following processes:
VLAN CLASSIFICATION
Same as for unicast switching.
LEARNING
Same as for unicast switching.
FILTERING
After learning the address the LBG1000A switch checks:
- Whether the source port or destination port is not in the forwarding state.
- Whether the source MAC address or destination MAC address is to be filtered.
- Whether the source port ID is the same as destination port ID.
If any of these conditions are met the LBG1000A switch drops the receiving. Otherwise it continues with the forwarding process
described below.

Manageable Gigabit Switch
FORWARDING
The LBG1000A switch floods the received multicast frame to all ports that are in forwarding state within the VLAN excluding the
source port. At the same time the switch ascertains the individual port’s VLAN tagging/untagging configuration and corresponding
VLAN ID to render the appropriate frame tagging when the frame is ready to be transmitted.
AGING
The LBG1000A switch performs the aging process for the <MAC addresses VLAN> pair in the switching database. Once a <MAC
address VLAN> pair is aged out the SDB is modified.
SPANNING TREE
The LBG1000A switch supports one Spanning Tree per bridged network.
User’s Manual 16

VLAN
A virtual LAN (VLAN) is a network of computers that behave as if they are connected to the same wire, even
though they may actually be physically located on different segments of a LAN. VLANs are analogous to a group
of end stations, perhaps on multiple physical LAN segments that are not constrained by their physical location and
can communicate as if they were on a common LAN.
VLANs are configured through software rather than hardware, which makes them extremely flexible. One of the
biggest advantages of VLANs is that when a computer is physically moved to another location, it can stay on the
same VLAN without any hardware reconfiguration.
Because VLANs are not limited by the hardware constraints that physically connect traditional LAN segments to a
network, they can define a network into various logical configurations. For example, VLANs can define a network
by application. In this scenario, a company might create one VLAN for multimedia users and another for email
users. VLANs can also define a network by department. For example, a company might have one VLAN for its
Engineering Department, another for its Marketing Department, and another for its Account Payable Department.
VLANs can also be set up according to the organization structure within a company. For example, the company
president might have his/her own VLAN, the executive staff might have a different VLAN, and the remaining
employees might have yet a different VLAN.
As these examples show, VLANs offer unparalleled flexibility. The following sections describe how deploying
VLANs can benefit organizations and reduce administration costs.

Broadcast Containment
In traditional networks traffic broadcasts to all network devices whether they are the intended recipients or not. However
VLANs can be set up to contain only those devices that need to communicate with each other. As a result VLANs
significantly reduce network congestion. In addition VLANs prevent broadcast storms from causing network meltdown due
to volumes of traffic.
Multicast-Based Multimedia Applications
Multimedia applications such as interactive training video conferencing and news-video transmissions require large
amounts of bandwidth. These applications are also extremely sensitive to variable delays which are unavoidable on a
shared Ethernet network. By defining a VLAN based on the IP multicast address for all subscribing members on the VLAN
sufficient bandwidth will be available for these application providing true multimedia on Ethernet.
Enhanced Security
Because VLANs are self-contained only the devices within the same VLAN can communicate with each other. If a device in
one VLAN wants to communicate with a device in another VLAN the traffic must go through a router.

VLAN Membership
VLAN implementation allows:
- Up to 256 VLANs in one switch.
- VLANs across multiple switches by using explicit or implicit tagging and the GARP/GVRP protocol defined in IEEE802.1p
and 802.1Q.
- An end station’s network interface card belong to multiple VLANs.
- A switch port to be associated with multiple VLANs.
DEFINITIONS OF VLAN MEMBERSHIP
VLAN implementation allows VLAN membership to be defined based on ports. Port-based VLANs are organized by physical port
number. For example switch ports 1 2 4 and 6 can be grouped on VLAN while server ports 3 5 7 and 8 can be on another
VLAN. Broadcasts from servers within each group would only go to the members of its own VLAN. This ensures that broadcast
storms cannot cause a network meltdown due to volumes of traffic.
VLAN MEMBERSHIP LEARNING
Port-based VLAN is defined using a static binding between a VLAN and its associated ports. The switch’s forwarding decision is
based on the destination MAC address and its associated port ID. Therefore to make valid forwarding and flooding decisions the
switch learns the relationship of the MAC address to its related port – and thus to the VLAN – at runtime.
REMOTE VLAN LEARNING
In addition to providing network management tools that allow network administrators to statically add and delete VLAN member
ports the switch also supports GVRP (GARP VLAN Registration Protocol). GVRP allows for dynamic registration of VLAN port
members within switch and across multiple switches.
Other than supporting dynamic updating of registration entries in a switch GVRP is used to communicate VLAN registration
information to other VLAN-aware switches so that a VLAN member can cover a wide span of switches on a network.
GVRP allows both VLAN-aware workstations and switches to issue and revoke VLAN memberships. VLAN-aware switches
register an propagate VLAN membership to all ports that belong to the active topology of the VLAN.
VLAN CONFIGURATION
The LBG1000A switch provides a Local/Remote Management Console Interface for VLAN configuration and management
An SNMP-based VLAN MIB is also provided.
Intra-VLAN Communication
The LBG1000A switch supports intra-VLAN communication through hardware as described in “Basic Functions” section.
Inter-VLAN Communication
The LBG1000A switch supports inter-VLAN communication using CPU-based routing software.

Class-of-Service (CoS) Support
The LBG1000A switch provides four transmit queues on each port, with a weighted round-robin scheme. These
functions can be used to provide independent priorities for various types of data including real-time video, real-time
voice, and best-effort data.
Priority assignment to packet-based switches is accomplished through explicit assignment by end stations, which
have applications that require a higher priority than best-effort data. This mechanism utilizes the IEEE802.1p and
802.1Q tag structure, which the switch uses to decide priority assignments for the received packets.
GVRP
In addition to network management tools that allow network administrators to statically add and delete VLAN
member ports, the routing switch supports GARP VLAN Registration Protocol (GVRP). GVRP supports dynamic
registration of VLAN port members within a switch and across multiple switches.
In addition to dynamically updating registration entries within a switch, GVRP is used to communicate VLAN
registration information to other VLAN-aware switches, so that members of a VLAN can cover a wide span of
switches on a network.
GVRP allows both VLAN-aware workstations and switches to issue and revoke VLAN memberships. VLAN-
aware switches register and propagate VLAN membership to all ports that are part of the active topology of the
VLAN.