Chapter 3
Switch Overview
LED Indicators and Port Descriptions
This chapter describes the function of the LEDs, and connectors of the front and back view of the switch.
All components of FS3-1600 on front and back panel are indicated in Figure 3- 1 and Figure 3- 2. More detailed descriptions are summarized in Table 3- 1.
Figure 3- 1: The Front View of FS3-1600
Table 3-1:
Components illustration of Front ViewItem | Label | Description |
1 | PWR | Green: DC power is available. |
2 | DIAG | Green: Self-Test OK. |
3 | FAN FAIL | Orange: FAN failure indication. |
4 | 1 ~ 16 | Prefixed port1 ~
port14 in the front end. MII Expansion port15 and port16 in the rear end. |
5 | 100 | Green: Represents the speed in 100Mbps. |
10 | Green: Represents the speed in 10Mbps. | |
6 | FDX / COL | Steady
Green: In full-duplex mode. Flashing Green : In half-duplex mode and appearing collisions. |
7 | ACT | Flashing Green: network activity. |
8 | 1 ~ 12 | Auto-sense 10/100M ports (MDI-X interface). |
9 | 13 ~ 14 | Auto-sense 10/100M ports (both MDI-X and MDI interfaces) |
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MDI-X | Default MDI-X interface. |
MDI | Press the push button to swap as MDI interface. |
Figure 3- 2: The Rear View of FS3-1600
Components illustration of Rear ViewItem | Label | Description |
1 | 100 Base FX/TX | Port 16: 100Base-FX or 100Base-TX MII Port |
2 | 100 Base FX/TX |
Port 15: 100Base-FX or 100Base-TX MII Port |
3 | Reset | Reset all of the registers of the switch and reboot the switch. |
4 | CONSOLE | Connect to the console port to operate the console management. The required RS-232 cable is bundled with the equipment. |
5 | FAN 1 | A fan for cooling
the internal components. (in rear end) |
FAN 2 & 3 | Fan 2 and 3 are located at the left side of rear end. | |
6 | 100-240V 50-60 Hz |
AC power receptacle - Accepts AC power cord (supplied) |
7 | ON | Flashing Green: network activity. |
The FS3-1600 switch supports 10Base-T and 10Base-T/100Base-TX ports.
10Base-T ports use RJ-45 connectors to attach to single end stations, 10Base-T hubs, or any 10Base-T-compatible device that uses standard 10Base-T adapters and wiring.
The 10Base-T ports can operate in half-duplex, full-duplex, or auto-sensing mode.
The 10Base-T ports are configured as MDI-X and provide a full 10Mbps bandwidth to attached devices. Maximum segment length is 100 meters (328 feet) over Category 3, 4 or 5 twisted-pair cable.
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.
The FS3-1600 switch supports trunk port and access port connection links. Any physical port can be defined as either a trunk port or an access port.
Trunk ports typically interconnect two switches. Packets sent from a trunk port are always VLAN tagged, unless overridden by a setting for a specific VLAN. A trunk port cannot be used to connect the FS3-1600 switch to another switch that does not support 802.1Q tagging.
Access ports typically connect the FS3-1600 switch to network nodes other than switches. Access ports can also connect the FS3-1600 switch to other switches that do not support 802.1Q tagging. Packets sent from an access port are always VLAN untagged, unless overridden by the specific setting for a specific VLAN.
Quality of Service (QoS) is one of the most important new functions in the evolution of networks. It provides the capability to prioritize and forward each packet in order to meet the needs of a variety of services - data, voice, and video simultaneously. This requires multiple priorities to be defined and recognized by the Layer-3 switch.
FS3-1600 switch is providing four transmit queues on each port, together with Weighted Fair Queuing. These functions could be used, for example, to provide independent priorities for real-time video, real-time voice, guaranteed-delivery data, and best-effort data. Some major industry players have already announced plans to assure four levels of priority on future products. And the IEEE 802.1p standards group is refining a standard for QoS based on multiple priorities.
Priority assignment in the FS3-1600 Switch is accomplished through explicit assignment by end stations, which have applications needing priority higher than best-effort data. This mechanism utilizes the IEEE 802.1p and 802.1Q tag structure. It requires only driver modification in end stations, which need to utilize QoS.
Additionally, implicit assignment of priorities is possible. This can be accomplished by intermediate devices, which could examine IP addresses and/or the TCP/UDP port numbers of packets in transit. However, this could be more difficult for network personnel to manage.
The FS3-1600 is designed to switch both VLAN-tagged and VLAN-untagged frames from a receiving port to one or more transmitting ports. The FS3-1600 performs a number of steps during the switching process, including:
- VLAN Classification
- Learning
- Filtering
- Forwarding
- Aging
VLAN-Aware Switches run a superset of micro-code used in the VLAN-Unaware Switches. When the FS3-1600 Switch performs frame-switching activities in a VLAN-aware environment, the Switch uses the <MAC Address, VLAN> pair instead of only using the MAC Address.
The following sections describe the VLAN Classification, Learning, Filtering, Forwarding, and Aging processes performed during unicast switching.
A receiving frame from an ingress port is classified to an associated VLAN, according to its source MAC address or ingress port number.
The classification is performed in the following sequence:
- Level-1 VLAN (port-based VLAN).
- If the frame is not associated with any Level-1 VLAN, it is classified into the default VLAN.
After VLAN classification, the FS3-1600 Switch Engine checks the <source MAC address, VLAN> pair in the switching database to see whether the <source MAC address, VLAN> pair is unknown.
- If the pair is unknown, the Switch Manager CPU is notified to learn the < source MAC address, VLAN> pair.
- If the pair is known, the Switch Engine checks whether the pair has a mismatched port ID.
If the port ID associated with the <source MAC address, VLAN> pair in the switching database is different than the receiving port, the Switch Engine modifies the port ID in the switching database and notifies the Switch Manager CPU about the new port change.
After performing the Learning process, the FS3-1600 Switch checks whether the:
- Source port or destination port is not in the forwarding state.
- The <source MAC address, VLAN> pair or <destination MAC address, VLAN> pair is to be filtered.
- Source port ID is the same as destination port ID.
If any of these conditions is met, the FS3-1600 Switch drops the receiving frame. Otherwise, the FS3-1600 Switch continues with the forwarding process (described below).
During the forwarding process, the FS3-1600 Switch checks whether the <destination MAC address, VLAN> pair is unknown.
- If the pair is unknown, the receiving frame floods to all ports except the source port.
- Otherwise, the receiving frame is forwarded to the port associated with the <destination MAC address, VLAN> pair.
The following sections describe the Multicast Switching process for VLAN-aware switches.
During multicast switching, FS3-1600 Switch checks whether the received frame is a BPDU (Bridge Protocol Data Unit).
A frame received from an ingress port is classified to an associated VLAN, according to its source MAC address or ingress port number. The classification is performed in the order of Level-1 VLAN (port-based VLAN). If the frame is not associated with any Level-1 VLAN, it is classified into the default VLAN.
If the <source MAC address, VLAN> pair of a received frame is unknown, the Switch Manager CPU learns the <source MAC address, VLAN> pair. Otherwise, the FS3-1600 Switch checks whether the <source MAC address, VLAN> pair has a mismatched port ID.
If the port ID associated with the <source MAC address, VLAN> pair in the switching database is different from the receiving port. The FS3-1600 Switch modifies the port ID in the switching database and notifies the Switch Manager CPU about the new port change.
If the source port is not in the forwarding state or the <source MAC address, VLAN> pair is to be filtered. Then the FS3-1600 Switch will discard the received multicast frame.
Otherwise, the received multicast frame floods to all ports in the VLAN, except the source port.
The FS3-1600 Switch also performs the aging process for the <MAC address, VLAN> pair in the switching database. Once a <MAC address, VLAN> pair is aged out, the switching database is modified and the Switch Manger CPU will perform house cleaning.
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 an extreme flexibility to organize your network on demand. The following sections describe how deploying VLANs can benefit organizations and reduce administration costs.
VLANs offer more cost-effective broadcast containment than routers.
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. Therefore, VLANs significantly reduce network congestion. In addition, VLANs prevent broadcast storms from causing a network meltdown due to volumes of traffic.
Reduced Cost of Network Administration
In traditional networks, administrators spend a great deal of time adding, moving, and deleting network users. For example, if users move to a different IP subnet location on the network, the administrator must manually revise the IP addresses of each end station. If users are deleted from the network, their IP address must also be deleted.
VLANs simplify these administrative activities. For example, if an end station in a VLAN moves to a different port in the network, an administrator can specify the new port assignment quickly and easily using the FS3-1600 Switch console management. This simplicity gives network administrators time to handle more important matters.
Enhanced Flexibility for Portable Network Users
LAN routers make it very difficult to support mobile users on a network. This is because a routers addressing scheme always expects to find a given address on a given segment. If that address moves to another segment, the routers tables need to be manually changed. This is a very time-consuming process, so user mobility is discouraged in a router-based network.
VLANs, on the other hand, use either MAC addresses (Level-2 VLANs) or network addresses (Level-3 VLANs) to decide who connects to whom and can therefore build up virtual teams of users based on MAC addresses. Regardless of location, the FS3-1600 Switch in a VLAN configuration allows users of predefined workgroups to communicate.
In this way, VLANs eliminate the limitation in a traditional router environment that requires all end stations sharing the same broadcast domain to reside in the same physical segment. Consequently, virtual workgroups can be dynamically reassigned according to changing needs over time, without having to move hardware or manually reconfigure the network.
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
.
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.
The FS3-1600 switchs VLAN implementation allows:
- Up to 32 VLANs in one switch.
- VLANs across multiple switches by using explicit or implicit tagging.
- An end stations network interface card to belong to multiple VLANs.
- A switch port to be associated with multiple VLANs.
Definitions of VLAN Membership
The FS3-1600 switchs VLAN implementation allows VLAN membership to be defined based on ports.
Level-1 VLAN is defined using static binding between a VLAN and its associated ports. The FS3-1600 switchs forwarding decision is based on the destination MAC address and its associated port ID. Therefore, to make valid forwarding and flooding decisions, the FS3-1600 Switch learns the relationship of the MAC address to its related port -- and thus to the VLAN -- at run-time.
To reduce the chance of uplink flooding, the FS3-1600 Switch supports remote VLAN learning within the FS3-1600 Switching Domain. The learning of remote VLANs is accomplished by piggybacking the VLAN ID in BPDUs used by the Spanning Tree Protocol.
When the FS3-1600 Switch receives an explicitly tagged BPDU, it learns the remote VLAN membership of a source link, while the STP ignores the VLAN Tag and processes as usual. All FS3-1600 Switches can then learn remote VLANs quickly and efficiently, and the VLAN membership binding will be known promptly to minimize unnecessary flooding.
VLAN Membership Distribution and Management
The IEEE 802.1Q committee is working on the Generic Attribute Registration Protocol (GARP) mechanism, defined by the 802.1P sub-working group, as a centralized way to dynamically register and deregister VLAN membership.
In addition, the 802.1Q committee is creating VLAN-related MIBs, which can be utilized as a way to globally distribute the VLAN definitions and membership across switches from different vendors.
Planet has been closely monitoring and actively participating in the 802.1Q committee, and plans to implement the standards for VLAN membership distribution and management as soon as they stabilize.
The FS3-1600 switch currently provides a Local/Remote Management Console Interface and Web Browser-based Interface for VLAN configuration and management. In addition, FS3-1600 implements Planets VLAN MIB for SNMP management. A standard VLAN MIB solution will be provided via firmware upgraded when the 802.1Q committee stabilizes its VLAN MIB standard proposal.
The FS3-1600 Switch supports intra-VLAN communication using ASIC with Cut-Through Switching or Store-and-Forward Switching. The forwarding decision of a packet will be affected by the filter setting, and by the Spanning Tree state of the source and destination ports.
The FS3-1600 Switch doesnt support inter-VLAN communications. FS3-1600 supports inter-VLAN communications using software-based routing with RIP protocol.
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