PLANET Web Switch Family Wgsw800.GIF (6460 bytes)

Web / SNMP Intelligent Products

WGSW-2402

24-Port Fast Ethernet Routing Switch with GbE Uplink


    Introduction

The PLANET WGSW-2402 switch is a flexible, high-speed, state-of-the-art routing switch that offers a combination of Ethernet, Fast Ethernet, and Gigabit Ethernet solutions.

This chapter introduce you the key features of the Switch and some basic concepts of how the WGSW-2402 works.

1.1 Using This User’s Manual

This User’s Manual contains all the information you need to install, configure, and troubleshoot the Switch.

In the following sections and Chapter, the term “Switch”, will indicates the WGSW-2402, “WebSwitch” shows PLANET range of Web Switch family, and “switch” for third party switches.


1.2 Package Contents

The WGSW-2402, routing switch package contains the followings:

If any of the above items missed, please contact with your local dealer immediately!


1.3 Product Features

The WGSW-2402 Switch provides the following key features.

- 6.54 Mpps maximum forwarding rate per system

- 148800pps on all Fast Ethernet ports

- 1488000pps on both Gigabit ports

- 2 K internal cache MAC address table

- Port-based VLAN

- 802.1Q tagged VLAN

- Limit number of MAC addresses learned per port

- Static MAC addresses stay in the filtering table

- Two 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

- Supports four groups total, maximum of eight ports per group

- Load sharing based on source and destination MAC

addresses

- 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

- SNMP agent: -MIB-2

- Bridge MIB (RFC1286)

- RMON MIB (RFC1757) -statistics, history, alarms, and events

- VLAN MIB (802.1Q)

- Java applet-based MIB browser


1.4 Physical Ports

The WGSW-2402 Switch supports 10Base-T/100Base-TX, and 1000Base-FX/1000Base-T ports.

1.4.1 10Base-T/100Base-TX Ports

The 10Base-T/100Base-TX ports use RJ-45 connectors and can operate in the following modes:

Half-duplex mode uses back-pressure flow control to prevent the receiving buffer from being overrun by data from a source node. Full-duplex mode uses the 802.3X flow control standard to prevent fast data traffic from over-running slow data traffic.

Auto-sensing mode automatically determines whether full-duplex or half-duplex mode is used after auto-negotiating with the other end of the link.

1.4.2 1000Base-FX Ports

1000Base-FX ports use fiber connections to provide links to high-speed network segments or individual workstations. Auto mode and Full-duplex mode supported for the fiber optic port.

When AUTO mode enabled, the port will detect the transfer mode automatically

1.4.3 1000Base-T Ports

1000Base-T ports use RJ-45 connections to provide links to high-speed network segments or individual workstations. The accepted wiring is 4-pair Category 5 or above UTP/STP cable, please refers to the module's guide for the details.

When AUTO mode enabled, the port will detect the transfer mode automatically


1.5 Basic Functions of Layer-2 Switching

If the <Destination MAC Address, Source MAC Address> of a receiving frame exists in the switch’s Distributed Flow Cache (DFC), the incoming frame is switched to the output port. Otherwise, the switch is responsible for switching both VLAN tagged and untagged frames

from a receiving port to one or more transmitting ports.

During the switching process, the switch performs multiple steps, including:

The following sections provide additional information about the tasks that the switch performs during unicast and multicast switching.

1.5.1 Unicast Switching

The following sections describe VLAN classification, learning, filtering, and forwarding for unicast switching.

1.5.1.1 VLAN Classification

When the switch receives a frame, it classifies the frame in one of two ways:

1.5.1.2 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.

1.5.1.3 Filtering

After learning the address, the switch checks:

1.5.1.4 Forwarding

During the forwarding process, the switch checks whether the <destination MAC address, VLAN> pair is unknown.

1.5.2 Multicast Switching

For a multicast switching, the switch checks whether the received frame is a BPDU. If a BPDU is received, the switch forwards the frame to for processing by the spanning tree protocol. Otherwise, the switch performs the following processes:

- Whether the source port or destination port is not in the for-warding state.

- The source MAC address is to be filtered.

- The source port ID is the same as destination port ID.

If any of these conditions are met, the switch drops the receiving frame. Otherwise, the switch performs the forwarding process.


1.6 VLAN

Virtual LANs (VLANs) are logical, independent workgroups within a network. These workgroups communicate as if they had a physical connection to the network. However, VLANs are not limited by the hardware constraints that physically connect traditional LAN segments to a network. As a result, VLANs can define a network into various logical configurations.

For example, VLANs can define a network by application. For instance, a company might create one VLAN for multimedia users and another for e-mail 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 Accounts Payable Department.

VLANs can also be set up according to the organization structure within a company. For example, the company president might have his own VLAN, his 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.

1.6.1 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 a network meltdown due to volumes of traffic.

1.6.2 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 applications, providing true multimedia on Ethernet.

1.6.3 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.

1.6.4 VLAN Membership

The WGSW-2402 VLAN implementation allows:

1.6.4.1 Definitions of VLAN Membership

WGSW-2402 VLAN implementation allows VLAN membership to be defined based on ports. That means, physical port numbers organizes port-based VLAN. For example, switch ports 1, 2, 4, and 6 can be one VLAN, while ports 3, 5, 7, and 8 can be another VLAN. Broadcasts from serves 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.

1.6.4.2 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 run-time.

1.6.4.3 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 a switch and across multiple switches.

In addition to supporting the 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 in a network.

GVRP allows both VLAN-aware workstations and Vertex switches to issue and revoke VLAN memberships. VLAN-aware WebSwitches register and propagate VLAN membership to all ports that belong to the active topology of the VLAN.

1.6.5 VLAN Configuration

PLANET currently provides a Local/Remote Management Console Interface for VLAN configuration and management. An SNMP-based VLAN MIB is also provided.

1.6.6 Intra-VLAN Communication

The Switch supports intra-VLAN communication using ASIC, as described in section 1.3

1.6.7 Inter-VLAN Communication

The Switch supports inter-VLAN communication using CPU-based routing software.


1.7 IEEE802.1p Support

The Switch provides two 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 a packet in the Switch is accomplished through explicit assignment by end stations, which have applications that require a higher priority than best-effort data. This mechanism utilizes the IEEE 802.1p and 802.1Q tag structure, which the switch uses to decide priority assignments for the received packets.


1.8 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 the 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 in a network.

GVRP allows both VLAN-aware workstations and the Switch 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.


1.9 IGMP Snooping and IP Multicast Filtering

The Internet Group Management Protocol (IGMP) runs between hosts and their immediately neighboring multicast routers. The protocol’s mechanisms allow a host to inform its local router that it wants to receive transmissions addressed to a specific multicast group.

Routers periodically query the LAN to determine if known group members are still active. If there is more than one router on the LAN performing IP multicasting, one of the routers is elected “querier” and assumes the responsibility of querying the LAN for group members. Based on the group membership information learned from the IGMP, a router can determine which (if any) multicast traffic needs to be for-warded to each of its “leaf” subnetworks. Multicast routers use this information, along with a multicast routing protocol, to support IP multicasting across the Internet.

IGMP provides the final step in an IP multicast packet delivery service since it is only concerned with the forwarding of multicast traffic from the local router to group members on directly attached subnetworks. The Switch support IP Multicast Filtering by:

The purpose of IP multicast filtering is to optimize a switched network's performance, so multicast packets will only be forwarded to those ports containing multicast group hosts members and routers instead of flooding to all ports in the subnet (VLAN).

The Switch with IP multicast filtering/switching capability not only passively monitor IGMP Query and Report messages, DVMRP Probe messages, PIM, and MOSPF Hello messages; they also actively send IGMP Query messages to learn locations of multi-cast routers and member hosts in multicast groups within each VLAN.

Note, however, IGMP neither alters nor routes any IP multicast packets. Since IGMP is not concerned with the delivery of IP multicast packets across subnets, an external IP multicast router is needed if IP multicast packets have to be routed across different subnets.

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Copyright (c) 2000, Planet Technology Corp.
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