DGS-3224TG Managed 24-Port Gigabit Ethernet Switch User’s Guide First Edition (May 2002) 651TG3224015 Printed In Taiwan RECYCLABLE
Wichtige Sicherheitshinweise 1. Bitte lesen Sie sich diese Hinweise sorgfältig durch. 2. Heben Sie diese Anleitung für den spätern Gebrauch auf. 3. Vor jedem Reinigen ist das Gerät vom Stromnetz zu trennen. Vervenden Sie keine Flüssig- oder Aerosolreiniger. Am besten dient ein angefeuchtetes Tuch zur Reinigung. 4. Um eine Beschädigung des Gerätes zu vermeiden sollten Sie nur Zubehörteile verwenden, die vom Hersteller zugelassen sind. 5. Das Gerät is vor Feuchtigkeit zu schützen. 6.
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Attenzione! Il presente prodotto appartiene alla classe A. Se utilizzato in ambiente domestico il prodotto può causare interferenze radio, nel cui caso è possibile che l`utente debba assumere provvedimenti adeguati.
Table of Contents About This Guide .................................................................................................................................. 1 Overview of this User’s Guide ............................................................................................................. 1 Introduction .......................................................................................................................................... 2 Features .......................................
Ingress Filtering ............................................................................................................................. 26 DHCP ............................................................................................................................................... 27 Configuring the Switch Using the Console Interface ............................................................................ 29 Before You Start .................................................................
Management..................................................................................................................................... 99 Security IP ..................................................................................................................................... 99 SNMP Manager .............................................................................................................................. 99 Trap Manager.............................................................
DGS-3224TG Gigabit Ethernet Switch User’s Guide A BOUT T HIS G UIDE This User’s guide tells you how to install your DGS-3224TG, how to connect it to your Gigabit Ethernet network, and how to set its configuration using the built-in console interface. Overview of this User’s Guide • Chapter 1, “Introduction.” Describes the Switch and its features. • Chapter 2, “Unpacking and Setup.” Helps you get started with the basic installation of the Switch. • Chapter 3, “Identifying External Components.
DGS-3224TG Gigabit Ethernet Switch User’s Guide 1 I NTRODUCTION This section describes the features of the DGS-3224TG. Features The DGS-3224TG was designed for departmental and enterprise connections. As an all-gigabit-port switch, it is ideal for backbone and server connection.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Management • RS-232 console port for out-of-band network management via a console terminal. • Spanning Tree Algorithm Protocol for creation of alternative backup paths and prevention of network loops. • SNMP V.1. • Fully configurable either in-band or out-of-band control via SNMP based software. • Flash memory for software upgrades. This can be done in-band via TFTP or out-of-band via the console.
DGS-3224TG Gigabit Ethernet Switch User’s Guide 2 U NPACKING AND S ETUP This chapter provides unpacking and setup information for the Switch. Unpacking Open the shipping carton of the switch and carefully unpack its contents.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 2-1. Installing rubber feet for desktop installation Rack Installation The DGS-3224TG can be mounted in an EIA standard-sized, 19-inch rack, which can be placed in a wiring closet with other equipment. To install, attach the mounting brackets on the switch’s side panels (one on each side) and secure them with the screws provided. Figure 2- 2A.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 2-2B. Installing in an equipment rack Power on The switch can be used with AC power supply 100-240 VAC, 50 - 60 Hz. The switch’s power supply will adjust to the local power source automatically and may be powered on without having any or all LAN segment cables connected. After the switch is plugged in, the LED indicators should respond as follows: • All LED indicators will momentarily blink.
DGS-3224TG Gigabit Ethernet Switch User’s Guide 3 I DENTIFYING E XTERNAL C OMPONENTS This chapter describes the front panel, rear panel, side panels, and LED indicators of the DGS-3224TG. Front Panel The front panel of the switch consists of LED indicators, an RS-232 communication port, 20 1000BASE-T ports, and 4 GBIC ports. Figure 3-1. Front panel view • An RS-232 DCE console port for setting up and managing the switch via a connection to a console terminal or PC using a terminal emulation program.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Side Panels The right side panel of the switch contains two system fans (see the top part of the diagram below). The left side panel contains heat vents. Figure 3-3. Side panel views of the Switch • The system fans are used to dissipate heat. The sides of the system also provide heat vents to serve the same purpose. Do not block these openings, and leave at least 6 inches of space at the rear and sides of the switch for proper ventilation.
DGS-3224TG Gigabit Ethernet Switch User’s Guide 4 C ONNECTING T HE S WITCH This chapter describes how to connect the DGS-3224TG to your Gigabit Ethernet network. Switch to End Node End nodes include PCs outfitted with a 10, 100 or 10/100 Mbps RJ-45 Ethernet/Fast Ethernet Network Interface Card (NIC) and most routers. An end node can be connected to the switch via a two-pair Category 3, 4, 5, or 5e UTP/STP cable—for optimal performance, Category 5e is recommended.
DGS-3224TG Gigabit Ethernet Switch User’s Guide • A 10BASE-T hub or switch can be connected to the switch via a two-pair Category 3, 4, 5, or 5e UTP/STP cable. • A 100BASE-TX hub or switch can be connected to the switch via a two-pair Category 5 or 5e UTP/STP cable. • A 1000BASE-T switch can be connected to the switch via four-pair straight Category 5 or 5e UTP/STP cable. Figure 4-2.
DGS-3224TG Gigabit Ethernet Switch User’s Guide 5 S WITCH M ANAGEMENT AND O PERATING C ONCEPTS This chapter discusses many of the concepts and features used to manage the switch, as well as the concepts necessary for the user to understand the functioning of the switch. Further, this chapter explains many important points regarding these features. Configuring the switch to implement these concepts and make use of its many features is discussed in detail in the next chapters.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Make sure the terminal or PC you are using to make this connection is configured to match these settings. If you are having problems making this connection on a PC, make sure the emulation is set to VT100. If you still don’t see anything, try hitting + r to refresh the screen.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 5-2. Switch Information menu In addition, you can also set an IP address for a gateway router. This becomes necessary when the network management station is located on a different IP network from the switch, making it necessary for management packets to go through a router to reach the network manager, and vice-versa. For security, you can set in the switch a list of IP Addresses of the network managers that allow you to manage the switch.
DGS-3224TG Gigabit Ethernet Switch User’s Guide from a factory reset in that configuration settings saved to non-volatile RAM used to reconfigure the switch. • Authentication Failure – This trap signifies that someone has tried to logon to the switch using an invalid SNMP community string. The switch automatically stores the source IP address of the unauthorized user.
DGS-3224TG Gigabit Ethernet Switch User’s Guide • • Collecting information about the status and current configuration of network devices. Modifying the configuration of network devices. The DGS-3224TG has a software program called an ‘agent’ that processes SNMP requests, but the user program that makes the requests and collects the responses runs on a management station (a designated computer on the network). The SNMP agent and the user program both use the UDP/IP protocol to exchange packets.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Each port on the switch is a unique collision domain and the switch filters (discards) packets whose destination lies on the same port as where it originated. This keeps local packets from disrupting communications on other parts of the network. For intrusion control, whenever a switch encounters a packet originating from or destined to a MAC address entered into the filter table, the switch will discard the packet.
DGS-3224TG Gigabit Ethernet Switch User’s Guide (Not userconfigurable except by setting priority below) address.
DGS-3224TG Gigabit Ethernet Switch User’s Guide • The path cost to the root from the transmitting port • The port identifier of the transmitting port The switch sends BPDUs to communicate and construct the spanning-tree topology. All switches connected to the LAN on which the packet is transmitted will receive the BPDU.
DGS-3224TG Gigabit Ethernet Switch User’s Guide • Disabled – the port only responds to network management messages and must return to the blocking state first A port transitions from one state to another as follows: • From initialization (switch boot) to blocking • From blocking to listening or to disabled • From listening to learning or to disabled • From learning to forwarding or to disabled • From forwarding to disabled • From disabled to blocking Figure 5-3.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Port cost 19 Bridge Priority 32,768 Table 5-3. Default STP Parameters User-Changeable STP Parameters The factory default setting should cover the majority of installations. However, it is advisable to keep the default settings as set at the factory, unless it is absolutely necessary. The user changeable parameters in the Switch are as follows: • Priority – A Priority for the switch can be set from 0 to 65535. 0 is equal to the highest Priority.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Setting-up STP using values other than the defaults can be complex. Therefore, you are advised to keep the default factory settings and STP will automatically assign root bridges/ports and block loop connections. Influencing STP to choose a particular switch as the root bridge using the Priority setting, or influencing STP to choose a particular port to block using the Port Priority and Port Cost settings is, however, relatively straight forward. Figure 5-4.
DGS-3224TG Gigabit Ethernet Switch User’s Guide The switch with the lowest Bridge ID (switch C) was elected the root bridge, and the ports were selected to give a high port cost between switches B and C. Note also that the example network topology is intended to provide redundancy to protect the network against a link or port failure – not a switch failure or removal. For example, a failure of switch A would isolate LAN 1 from connecting to LAN 2 or LAN 3.
DGS-3224TG Gigabit Ethernet Switch User’s Guide IEEE 802.1Q (tagged) VLANs are implemented on the DGS-3224TG. 802.1Q VLANs require tagging, which enables them to span the entire network (assuming all switches on the network are IEEE 802.1Q-compliant). VLANs allow a network to be segmented in order to reduce the size of broadcast domains. All packets entering a VLAN will only be forwarded to the stations (over IEEE 802.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 5-6. IEEE 802.1Q Packet Forwarding 802.1Q VLAN Tags The figure below shows the 802.1Q VLAN tag. There are four additional octets inserted after the source MAC address. Their presence is indicated by a value of 0x8100 in the EtherType field. When a packet’s EtherType field is equal to 0x8100, the packet carries the IEEE 802.1Q/802.1p tag.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 5-7. IEEE 802.1Q Tag The EtherType and VLAN ID are inserted after the MAC source address, but before the original EtherType/Length or Logical Link Control. Because the packet is now a bit longer than it was originally, the Cyclic Redundancy Check (CRC) must be recalculated. Figure 5-8. Adding an IEEE 802.1Q Tag Port VLAN ID Packets that are tagged (are carrying the 802.1Q VID information) can be transmitted from one 802.
DGS-3224TG Gigabit Ethernet Switch User’s Guide destination address (found in the switch’s forwarding table). If the PVID of the port that received the packet is different from the PVID of the port that is to transmit the packet, the switch will drop the packet. Within the switch, different PVIDs mean different VLANs (remember that two VLANs cannot communicate without an external router). So, VLAN identification based upon the PVIDs cannot create VLANs that extend outside a given switch (or switch stack).
DGS-3224TG Gigabit Ethernet Switch User’s Guide If the packet is not tagged with VLAN information, the ingress port will tag the packet with its own PVID as a VID. The switch then determines if the destination port is a member of the same VLAN (has the same VID) as the ingress port. If it does not, the packet is dropped. If it has the same VID, the packet is forwarded and the destination port transmits it on its attached network segment.
DGS-3224TG Gigabit Ethernet Switch User’s Guide 28
DGS-3224TG Gigabit Ethernet Switch User’s Guide 6 C ONFIGURING THE S WITCH U SING THE C ONSOLE I NTERFACE Your 24-port Gigabit Ethernet switch supports a console management interface that allows you to set up and control your switch, either with an ordinary terminal (or terminal emulator), or over the network using the TCP/IP Telnet protocol. You can use this facility to perform many basic network management functions.
DGS-3224TG Gigabit Ethernet Switch User’s Guide You can also access the same functions over a Telnet interface. Once you have set an IP address for your switch, you can use a Telnet program (in VT-100 compatible terminal mode) to access and control the switch. All of the screens are identical, whether accessed from the console port or from a Telnet interface. Console Usage Conventions The console interface makes use of the following conventions: 1.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-1. Initial screen, first time connecting to the switch Note: There is no initial username or password. Leave the Username and Password fields blank. Press Enter in both the Username and Password fields. You will be given access to the main menu shown below: Figure 6-2. Main menu Note: The first user automatically gets Root privileges (See Table 6-1). It is recommended to create at least one Root-level user for the switch.
DGS-3224TG Gigabit Ethernet Switch User’s Guide User Accounts Management To create a new user account, highlight User Accounts Management from the main menu and press Enter: Figure 6-3. Main menu Figure 6-4.
DGS-3224TG Gigabit Ethernet Switch User’s Guide From the main menu, highlight User Accounts Management and press Enter, then the Setup User Accounts screen appears. 1. Toggle the Action field to using the space bar. This will allow the addition of a new user. The other options are - this allows the deletion of a user entry, and - this allows for changes to be made to an existing user entry. 2. Enter the new user name, assign an initial password, and then confirm the new password.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Save Changes The DGS-3224TG has two levels of memory; normal RAM and non-volatile or NV-RAM. Configuration changes are made effective by highlighting APPLY and pressing Enter. When this is done, the settings will be immediately applied to the switching software in RAM, and will immediately take effect. Some settings, though, require you to restart the switch before they will take effect.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-6. Save changes screen Once the switch configuration settings have been saved to NV-RAM, they become the default settings for the switch. These settings will be used every time the Switch is rebooted. Factory Reset The only way to change the configuration stored in NV-RAM is to save a new configuration using Save Changes, or to execute a Load Factory Default Configuration from the System Reboot menu (under Reboot on the main menu).
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-7. Main menu Highlight Reboot from the main menu and press Enter. Figure 6-8. System Reboot menu Highlight the appropriate choice and press Enter to reset the switch’s NV-RAM to the factory default settings (or just reboot the switch).
DGS-3224TG Gigabit Ethernet Switch User’s Guide purchased. The Load Factory Default Configuration Except IP Address option is used when the switch will be managed by the Telnet manager, which requires knowledge of the switch’s IP address to function. Logging Onto The Switch Console To log in once you have created a registered user, from the login screen: 1. Type in your Username and press Enter. 2. Type in your Password and press Enter. 3.
DGS-3224TG Gigabit Ethernet Switch User’s Guide 5. If the privilege level is to be changed, toggle the Access Level field until the appropriate level is displayed – Root, User+ or User. 6. Highlight APPLY and press Enter to make the change effective. 7. You must enter the configuration changes into the non-volatile ram (NV-RAM) using Save Changes from the main menu if you want the configuration to be used after a switch reboot. Only a user with Root privileges can make changes to user accounts.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-10. Configuration menu Configure IP Address Some settings must be entered to allow the switch to be managed from an SNMP-based Network Management System such as SNMP v1 or to be able to access the switch using the Telnet protocol. The Remote Management Setup screen lets you specify how the switch will be assigned an IP address to allow the switch to be identified on the network.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-11. Remote Management Setup screen The switch needs to have an IP address assigned to it so that an in-band network management system (e.g. Telnet) client can find it on the network. The Remote Management Setup screen allows you to change the settings for the two different management interfaces used on the switch: the Ethernet interface used for in-band communication, and the SLIP interface used over the console port for out-ofband communication.
DGS-3224TG Gigabit Ethernet Switch User’s Guide IP Address – Determines the IP address used by the switch for receiving SNMP and Telnet communications. These fields should be of the form xxx.xxx.xxx.xxx, where each xxx is a number (represented in decimal) between 0 and 255. This address should be a unique address on a network assigned to you by the central Internet authorities.
DGS-3224TG Gigabit Ethernet Switch User’s Guide You can also enter the name of the System, its location, and the name and telephone number of the system administrator. It is recommended that the person responsible for the maintenance of the network system that this switch is installed on be listed here. Configure Advanced Switch Features Select ADVANCED SETTINGS at the bottom of the Switch Information menu and press Enter to access the following Configure Advanced Switch Features menu: Figure 6-13.
DGS-3224TG Gigabit Ethernet Switch User’s Guide • Scheduling Mechanism for CoS Queues: – There are two Class of Service queue options, RoundRobin and Strict. If Strict is selected, when the highest priority queue is full, those packets will be the first to be forwarded. If RoundRobin is selected, the forwarding is based on the settings made on the Class of Service Configuration screen.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-15. Configure Ports screen Toggle the View Ports field, using the space bar, to view the configuration of either ports 1 through 12, 13 through 20, or 21 through 24. To configure a specific port, toggle the Configure Port from [ ] to [ ] field until the appropriate port number or port range appears. Toggle the State field to either enable or disable a given port.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-16. Configure Spanning Tree menu The Spanning Tree Protocol (STP) operates on two levels: on the switch level, the settings are globally implemented. On the port level, the settings are implemented on a per user-defined group basis. Note: The factory default settings should cover the majority of installations. Therefore, it is advisable to keep the default settings as set at the factory unless it is absolutely necessary to change them.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Note: Observe the following formulas when setting the above parameters: Max. Age ≤ 2 x (Forward Delay - 1 second) Max. Age ≥ 2 x (Hello Time + 1 second) Port Spanning Tree Settings In addition to setting Spanning Tree parameters for use on the switch level, the DGS-3224TG allows for the configuration of Spanning Tree Protocol on individual ports. To define individual ports, highlight Port Settings on the Configure Spanning Tree menu above and press Enter.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-18. Configure Static (Destination-Address Forwarding) Table menu Setup Unicast Forwarding Table Highlight Configure Static Forwarding Table on the menu above to access the following screen: Figure 6-19. Setup Unicast Forwarding Table screen The Action field can be toggled between Add/Modify and Delete using the space bar.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Address field. There are two static unicast forwarding types to select from, Permanent and DeleteOnReset. Enter the port number in the Port field. Highlight APPLY and press Enter to make the changes current. Use Save Changes from the main menu to enter the changes into NV-RAM. Setup Static Multicast Forwarding Table To edit the IEEE 802.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Note: The DGS-3224TG supports a maximum of 16K multicast MAC address entities. Configure VLANs The switch reserves one VLAN, VID = 1, called the DEFAULT_VLAN for internal use. The factory default setting assigns all ports on the switch to the DEFAULT_VLAN. As new VLANs are configured, their respective member ports are removed from the DEFAULT_VLAN. If the DEFAULT_VLAN is reconfigured, all ports are again assigned to it.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-22. 802.1Q Static VLAN Settings screen To create an 802.1Q VLAN, enter a VLAN ID number in the VID field and a name for the new VLAN in the VLAN Name field. To set the 802.1Q VLAN membership status of a port: To enter the 802.1Q VLAN status for a port, highlight the first field of Egress/Forbidden. Each port’s 802.
DGS-3224TG Gigabit Ethernet Switch User’s Guide with the PVID (Port VLAN Identifier – see below). When a tagged packet exits the port, the packet header is unchanged. If the port is attached to a device that is not IEEE 802.1Q VLAN compliant (VLAN-tag unaware), then the port should be set to U – Untagged. If the port is attached to a device that is IEEE 802.1Q VLAN compliant, (VLAN-tag aware), then the port should be set to T – Tagged.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Ingress Filter Settings To set ingress filtering on a port, highlight Configure Port Ingress Filter on the IEEE 802.1Q VLANs Configuration menu and press Enter: Figure 6-24. Ingress Filter Settings screen Highlight the Configure Port from [1 ] to [1 ] field and enter the range of port numbers you want to configure. Then use the space bar to toggle between On and Off in the Ingress Filter field.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-25. Port GVRP Settings screen This screen allows you to enable or disable GARP VLAN Registration Protocol (GVRP), where GARP is the Generic Attribute Registration Protocol, on individual ports. Enter the range of ports to be configured in the first two fields and then toggle the GVRP State to On. Press APPLY to let your changes take effect. GVRP updates dynamic VLAN registration entries and communicates the new VLAN information across the network.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-26. IGMP Snooping Settings screen To configure IGMP Snooping: Toggle the Switch IGMP Snooping field to Enabled. Toggle the Querier State field to the appropriate choice between Non-Querier, V1-Querier, and V2-Querier to determine the version of IGMP that is used in your network. A value between 1 and 255 can be entered for the Robustness Variable (default is 2). The Query Interval can be set between 1 and 65500 seconds (default is 125 seconds).
DGS-3224TG Gigabit Ethernet Switch User’s Guide • Max Response:[10] – Sets the maximum amount of time allowed before sending an IGMP response report. A value between 1 and 25 seconds can be entered, with a default of 10 seconds. Configure Trunk To configure a port trunking group, highlight Configure TRUNK on the Configuration menu and press Enter. Figure 6-27. Link Aggregation screen Link aggregation, or port trunking, allows several ports to be grouped together and to act as a single link.
DGS-3224TG Gigabit Ethernet Switch User’s Guide on the Switch, STP will block one entire group – in the same way STP will block a single port that has a redundant link. The user-changeable parameters in the switch are as follows: • Group ID:[1] – This field is for a group ID number for the port trunking group. • Group Name:[ • Member ports – Toggle between M to indicate membership of the port trunking group, or a dash (–) to indicate non-membership.
DGS-3224TG Gigabit Ethernet Switch User’s Guide monitoring/troubleshooting device such as a sniffer or an RMON probe. Finally, toggle the Mirror Status field to Enabled, highlight APPLY, and press Enter. Note: You cannot mirror a fast port onto a slower port. For example, if you try to mirror the traffic from a 100 Mbps port onto a 10 Mbps port, this can cause throughput problems.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-30. Class of Service Configuration menu This menu allows you to set the following features: • Max. Packets – Use the space bar in this column to select the maximum number of packets the Class of Service priority queue can hold. The range of values is from 0 to 512 packets. • Max. Latency – The maximum allowable time a packet will stay in the CoS queue, in microseconds and seconds.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-31. Port Maxlimit Drop Settings screen The Switch divides the buffer into four parts: Queue0, Queue1, Queue2, and Queue3. Queue0 is the highest priority and Queue3 is the lowest. Press APPLY to let the change take effect. Port Default Priority assignment Select Configure Default Priority and press Enter to access the following screen: Figure 6-32.
DGS-3224TG Gigabit Ethernet Switch User’s Guide This screen allows you to set a default priority for packets that have not already been assigned a priority value. After filling out the two fields offered, press APPLY to let your changes take effect. Traffic Class Configuration Select Configure Traffic of Class and press Enter to access the following screen: Figure 6-33.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-34. Serial Port and SLIP Settings screen The following fields can then be set: • Baud Rate:<9600> – Sets the serial bit rate that will be used to communicate the next time the switch is restarted. Available speeds are 9600, 19200, 38400 and 115200 bits per second. The default setting is 9600. • Data Bits:<8> – Select 7 or 8. The default is 7. • Parity: – Choose from None, Even or Odd. The default is None. • Stop Bits:<1> – Select 1 or 2.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-35. Network Monitoring Menu Port Utilization To view the port utilization of all the ports on the switch, highlight Port Utilization on the Network Monitoring Menu and press Enter: Figure 6-36.
DGS-3224TG Gigabit Ethernet Switch User’s Guide The Port Utilization screen shows the number of packets transmitted and received per second and calculates the percentage of the total available bandwidth being used on the port (displayed under %Util.). Highlight CLEAR COUNTER and press Enter to reset the counters. Port Error Packets To view the error statistics for a port, highlight Port Error Packets on the Network Monitoring Menu and press Enter: Figure 6-37.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-38. Packet Analysis screen In addition to the size of packets received or transmitted by the selected port, statistics on the number of unicast, multicast, and broadcast packets are displayed. Highlight CLEAR COUNTER and press Enter to reset the counters.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-39. Browse Address Table screen The Browse By field can be toggled between ALL, MAC Address, Port, and VLAN. This sets a filter to determine which MAC addresses from the forwarding table are displayed. ALL specifies no filter. To search for a particular MAC address: Toggle the Browse By field to MAC Address. A MAC Address field will appear. Enter the MAC address in the field and press Enter.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-40. Switch History screen IGMP Snooping This allows the switch’s IGMP Snooping table to be viewed. IGMP Snooping allows the switch to read the Multicast Group IP address and the corresponding MAC address from IGMP packets that pass through the switch. The ports where the IGMP packets were snooped are displayed, signified with an M. The number of IGMP reports that were snooped is also displayed in the Reports field.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-41. IGMP Snooping Status screen Enter a VLAN ID number in the first field and press GO to display the desired IGMP Snooping Status screen. Browse Multicast Status Figure 6-42.
DGS-3224TG Gigabit Ethernet Switch User’s Guide This read-only screen displays the VLAN ID, group address, and static/IGMP snooping port list for multicast addresses. VLAN Status This allows the status for each of the switch’s VLANs to be viewed. To view the VLAN Status table, highlight VLAN Status on the Network Monitoring Menu and press Enter. Figure 6-43. VLAN Status screen This read-only screen displays VLAN information.
DGS-3224TG Gigabit Ethernet Switch User’s Guide The SNMP allows up to four different community names to be defined. The community name public is defined by default; you can change this name in addition to adding others. You will need to coordinate these names with the community name settings you use in your network management system. Choose SNMP Manager Configuration to access the third item on the main menu. The following screen appears: Figure 6-44.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-45. Switch Utilities menu Note: Trivial File Transfer Protocol (TFTP) services allow the switch firmware to be upgraded by transferring a new firmware file from a TFTP server to the Switch. A configuration file can also be loaded into the Switch from a TFTP server, switch settings can be saved to the TFTP server, and a history log can be uploaded from the Switch to the TFTP server.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-46. Upgrade Firmware screen Enter the IP address of the TFTP server in the Server IP Address field. Note: The TFTP server must be on the same IP subnet as the switch. Enter the path and the filename to the firmware file on the TFTP server. Note: The TFTP server must be running TFTP server software to perform the file transfer. TFTP server software is a part of many network management software packages, or can be obtained as a separate program.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-47. Use Configuration File on TFTP Server screen Enter the IP address of the TFTP server and specify the location of the switch configuration file on the TFTP server. Highlight APPLY and press Enter to record the IP address of the TFTP server. Use Save Changes from the main menu to enter the address into NV-RAM Highlight START and press Enter to initiate the file transfer.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-48. Save Settings to TFTP Server screen Enter the IP address of the TFTP server and the path and filename of the settings file on the TFTP server and press APPLY. Highlight START and press Enter to initiate the file transfer. Save History Log to TFTP Server To save a History Log on a TFTP server, highlight Save History Log to TFTP Server and press Enter.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-49. Save Log to TFTP Server screen Enter the IP address of the TFTP server and the path and filename for the history log on the TFTP server. Highlight APPLY and press Enter to make the changes current. Highlight START and press Enter to initiate the file transfer. Ping Test To test the connection with another network device using Ping, highlight Ping Test and press Enter.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-50. Ping screen Enter the IP address of the network device to be Pinged and the number of test packets to be sent (3 is usually enough). Highlight START and press Enter to initiate the Ping program. Reboot The DGS-3224TG has several reboot options. To reboot the switch from the console, highlight Reboot from the main menu and press Enter.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-51. System Reboot menu The reboot options are as follows: • Reboot – Simply restarts the switch. Any configuration settings not saved using Save Changes from the main menu will be lost. The switch’s configuration will be restored to the last configuration saved in NV-RAM. • Save Configuration & Reboot – Saves the configuration to NV-RAM (identical to using Save Changes) and then restarts the switch.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 6-52. System Reboot confirmation screen To reboot the switch, in the mode entered above, highlight Yes and press Enter.
DGS-3224TG Gigabit Ethernet Switch User’s Guide 7 W EB -B ASED N ETWORK M ANAGEMENT Introduction The DGS-3224TG offers an embedded Web-based (HTML) interface allowing users to manage the switch from anywhere on the network through a standard browser, such as Opera, Netscape Navigator/Communicator, or Microsoft Internet Explorer. The Web browser acts as a universal access tool and can communicate directly with the switch using the HTTP protocol.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Click OK as there is no preset user name or password on the switch. This opens the main page in the management module. The top panel shows a real-time front panel display of the DGS-3224TG. Clicking on an individual port on this display will connect you to the Rx Packets Analysis window (see Monitoring→Packets→ Received(RX)) for a detailed description) The panel on the left-hand side contains the main menu.
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DGS-3224TG Gigabit Ethernet Switch User’s Guide These are the major categories for switch management. If the sub-menus for each main category do not appear, click on the small square hyperlink to the left of the folder icon. The switch management features available in the Web-based are explained below.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Configuration The first category includes: IP Address, Switch Information, Advanced Settings, Port Configuration, Port Mirroring, Port Trunking, IGMP Snooping, Spanning Tree, Static Forwarding Table, VLANs, Port Default Priority, Class of Traffic, Class of Service, and RS232&SLIP, as well secondary screens. IP Address Figure 7-1.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Switch Information Figure 7-2. Switch Information (Basic Settings) window To set basic switch settings, enter a System Name in the first field, the physical location of the switch in the System Location field, and the name of the contact person responsible for the switch in the System Contact field. Then click Apply. The information is described as follows: • Device Type – A description of the switch type.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Advanced Settings Figure 7-3. Switch Information (Advanced Settings) window After making the desired advanced setting Layer 2 changes, click Apply to let them take effect. The information in the window is described as follows: • Auto-Logout [Never] – This sets the time the interface can be idle before the switch automatically logs-out the user. The options are 2 minutes, 5 minutes, 10 minutes, 15 minutes, or Never.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Port Configuration Figure 7-4. Port Configuration window Select the port you want to configure by using the drop-down menus in the From and To fields. Follow these steps: 1. Enable or disable the port. If you choose Disabled in the State field, devices connected to that port cannot use the switch, and the switch purges their addresses from its address table after the MAC address aging time elapses. 2.
DGS-3224TG Gigabit Ethernet Switch User’s Guide capabilities of the device at the other end. The other selections allow you to force the port to operate in the specified manner. Select 1000M/Full for port operation at 1000 Mbps and full duplex. Select 100M/Half for port operation at 100 Mbps and half duplex Select 100M/Full for port operation at 100 Mbps and full duplex. Select 100M/Half for port operation at 100 Mbps and half duplex. Select 10M/Full for port operation at 10 Mbps and full duplex.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Port Trunking Figure 7-6. Port Trunking Settings window The Switch supports up to 6 trunk groups. Trunks are groups of ports that are banded together to form a single, logical, high-bandwidth data pipe. The maximum number of member ports for a trunk group is 16. To create or modify a trunk group, enter a name in the first field, check the ports that will compose the port trunk, and change the Status field to Enabled. Click Apply to activate your settings.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Internet Group Management Protocol (IGMP) snooping allows the switch to recognize IGMP queries and reports sent between network stations or devices and an IGMP host. When enabled for IGMP snooping, the switch can open or close a port to a specific device based on IGMP messages passing through the switch. To set up IGMP snooping, enter a VLAN ID number in the first field and change the State field to Enabled.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 7-8. Switch Spanning Tree Settings window Click Apply after making changes to the window above. Parameters that you can change are: • Spanning Tree Protocol – This drop-down menu allows you to enable the Spanning Tree Protocol setting. • Bridge Max Age (6-40 Sec) <20> – The Maximum Age can be from 6 to 40 seconds.
DGS-3224TG Gigabit Ethernet Switch User’s Guide STP Port Settings Figure 7-9. STP Port Settings window To configure Spanning Tree Protocol functions for individual ports, enter the desired information in the fields on this window (see the descriptions below for assistance) and then click Apply. The information on the window is described as follows: • From – Enter the first port to be configured. • To – Enter the last port to be configured.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Static Forwarding Table Static Unicast Forwarding Figure 7-10. Add Static Forward window The window above allows you to set up static packet forwarding on the switch. The information on the window is described as follows: • MAC Address – The MAC address from which packets will be statically filtered. • VID – The VLAN ID number of the VLAN to which the MAC address belongs. • Type – Select the filter type, Permanent or DeleteOnReset.
DGS-3224TG Gigabit Ethernet Switch User’s Guide • Port Map – Allows the selection of ports that will be members of the static multicast group and ports that have no restrictions from joining dynamically. VLANs This section includes Static VLAN Entry and Port VLAN ID (PVID). Static VLAN Entry Figure 7-12. 802.1Q Static VLANs window To add an entry to this table, click New and then fill in the appropriate information in the window below. To delete an entry, click the icon in the Delete column.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 7-14. 802.1Q Static VLAN Setup window To modify an entry, click the pointer icon next to the appropriate table entry on the 802.1Q Static VLANs window and then complete the appropriate information on the window above. Click Apply to let your changes take effect. To delete an entry, click the X icon next to the appropriate table entry on the 802.1Q Static VLANs window and then click Apply.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Port VLAN ID (PVID) Figure 7-15. 802.1Q Port Settings window This window allows you to assign a Port VLAN ID (PVID) number, enable or disable the ingress filtering check, and enable or disable GVRP for individual ports. Ingress filtering means that a receiving port will check to see if it is a member of the VLAN ID in the packet before forwarding the packet.
DGS-3224TG Gigabit Ethernet Switch User’s Guide create and manage VLANs on switches connected through 802.1Q ports. Click Apply to let your changes take effect. The information on the window is described as follows: • PVID – PVID is used to decide whether received tagged packets belong to a VLAN. • Ingress – Ingress filtering is used to check if the received port is a member port of the VLAN whose VID is equal to the VID of incoming packets.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 7-16. Default Port Priority assignment window This window allows you to set a default priority for packets that have not already been assigned a priority value. After filling out the two fields offered, click Apply to let your changes take effect. Class of Traffic Figure 7-17.
DGS-3224TG Gigabit Ethernet Switch User’s Guide can be entered in this field are from 1 to 255. Entering zero instructs the switch to continue processing packets until there are no more packets in the CoS transaction queue. • Max. Latency – The maximum allowable time a packet will stay in the CoS queue, in microseconds and seconds. The packets in this queue are not delayed more than the maximum allowable latency entered in this field. Maximum latency takes precedence over the CoS scheduling algorithm.
DGS-3224TG Gigabit Ethernet Switch User’s Guide The switch divides the buffer into four parts: Queue0, Queue1, Queue2, and Queue3. Queue0 is the highest priority and Queue3 is the lowest. Use the window above to select the ports for each of the four queue priorities. Turn the Class State to On for the specified range of ports and then click Apply to let your changes take effect. RS232 & SLIP Figure 7-20.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Management This category includes: Security IP, SNMP Manager, Trap Manager, and User Accounts. Security IP Figure 7-21. Security IP Management window Use this window to specify IP addresses that are allowed to access the switch. SNMP Manager Figure 7-22. SNMP Manager Configuration window To use the functions on this window, enter the appropriate SNMP information. You may enter up to four entries. Click Apply to put the settings into effect.
DGS-3224TG Gigabit Ethernet Switch User’s Guide • Community String – A user-defined SNMP community name. • Access Right – The permitted access of Read-Only or Read-Write using the SNMP community name. • Status – Option to set the current community string to Valid or Invalid. Trap Manager Figure 7-23. SNMP Trap Manager Configuration window A trap receiving station is a device that constantly runs a network management application to receive and store traps. You may enter up to four entries.
DGS-3224TG Gigabit Ethernet Switch User’s Guide • Access Right – Displays the current access level assigned to each corresponding user. There are three access levels: User, User+, and Root. A Root user has full read/write access, while a User has read only access. A User+ has the same privileges as a User, but with the added ability to restart the switch. • New – Select this hyperlink to add a new user to the table. User Account Modify Table Figure 7-25.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 7-26. Utilization of Port window The information is described as follows: • Time Interval – Select the desired setting between 1s and 60s, where “s” stands for seconds. The default value is one second. • Record Number – Select number of times the switch will be polled between 20 and 200. The default value is 20. • Show/Hide – Check whether or not to display Utilization.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Received (RX) Figure 7-27.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 7-28. Rx Packets Analysis window (Table) The information is described as follows: • Time Interval – Select the desired setting between 1s and 60s, where “s” stands for seconds. The default value is one second. • Record Number – Select number of times the switch will be polled between 20 and 200. The default value is 20. • Bytes – Counts the number of bytes received on the port. • Packets – Counts the number of packets received on the port.
DGS-3224TG Gigabit Ethernet Switch User’s Guide UMB-cast (RX) Figure 7-29.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 7-30. Rx Packets Analysis window for UMB_cast (Table) The information is described as follows: • Time Interval – Select the desired setting between 1s and 60s, where “s” stands for seconds. • Record Number – Select number of times the switch will be polled between 20 and 200. • Multicast – Counts the total number of good packets that were received by a multicast address.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Transmitted (TX) Figure 7-31.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 7-32. Tx Packets Analysis window (Table) The information is described as follows: • Time Interval – Select the desired setting between 1s and 60s, where “s” stands for seconds. The default value is one second. • Record Number – Select number of times the switch will be polled between 20 and 200. The default value is 20. • Bytes – Counts the number of bytes successfully sent from the port.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Received (RX) Figure 7-33. Rx Error Analysis window (Line Chart) Figure 7-34.
DGS-3224TG Gigabit Ethernet Switch User’s Guide • Time Interval – Select the desired setting between 1s and 60s, where “s” stands for seconds. The default value is one second. • Record Number – Select number of times the switch will be polled between 20 and 200. The default value is 20. • CRCError – Counts otherwise valid frames that did not end on a byte (octet) boundary. • UnderSize – The number of frames detected that are less than the minimum permitted frame size of 64 bytes and have a good CRC.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Transmitted (TX) Figure 7-35.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 7-36. Packet Analysis window (Table) The information is described as follows: • Time Interval – Select the desired setting between 1s and 60s, where “s” stands for seconds. The default value is one second. • Record Number – Select number of times the switch will be polled between 20 and 200. The default value is 20. • LateColl – Counts the number of times that a collision is detected later than 512 bit-times into the transmission of a packet.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Size The Web Manager allows packets transmitted and received by the switch, arranged in six groups, to be viewed as either a line graph or a table. The two windows offered are as follows: Packet Size Figure 7-37.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 7-38. Packet Analysis window (Table) The information is described as follows: • Time Interval – Select the desired setting between 1s and 60s, where “s” stands for seconds. The default value is one second. • Record Number – Select number of times the switch will be polled between 20 and 200. The default value is 20.
DGS-3224TG Gigabit Ethernet Switch User’s Guide • View Table – Clicking this button instructs the switch to display a table rather than a line graph. • View Line Chart – Clicking this button instructs the switch to display a line graph rather than a table. MAC Address Table The Web Manager allows the switch’s MAC address table (sometimes referred to as a forwarding table) to be viewed: Figure 7-39.
DGS-3224TG Gigabit Ethernet Switch User’s Guide The information is described as follows: • Search by VLAN ID – Allows the forwarding table to be browsed by VLAN ID (VID). • Search by MAC Address – Allows the forwarding table to be browsed by MAC Address. • Search by Port – Allows the forwarding table to be browsed by port number. • Jump – Allows the user to move to a sector of the database corresponding to a user defined port, VLAN, or MAC address. • Find – Click the icon to find the data entry.
DGS-3224TG Gigabit Ethernet Switch User’s Guide VLAN Multicast Table This read-only table displays the VLAN multicast table for each VLAN ID on the switch. Figure 7-41. VLAN Multicast Table window IGMP Multicast Table This read-only table displays the IGMP multicast table for each VLAN ID on the switch. Figure 7-42. IGMP Multicast Table window VLAN Status This table displays VLAN information for the specified VLAN. Figure 7-43.
DGS-3224TG Gigabit Ethernet Switch User’s Guide • Current Egress Ports – Displays the current egress ports on the VLAN. • Current Untagged Ports – Displays the current untagged ports on the VLAN. Maintenance This category includes TFTP Services (Update Firmware, Configuration File, Save Settings, and Save History Log), Switch History, Ping Test, Save Changes, Factory Reset, Restart System, Connection Timeout, and Logout.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 7-45. Use Configuration File on Server window Enter the IP address of the TFTP Server in the Server IP Address field and the complete path and file name of the firmware file for the switch. Click Apply to enter the server’s IP address into the switch’s RAM (use Save Changes to enter the address into the switch’s non-volatile RAM). Click Start to initiate the file transfer.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 7-47. Save Switch History To TFTP Server window Enter the IP address of the TFTP Server in the Server IP Address field and the complete path and file name of the firmware file for the switch. Click Apply to enter the server’s IP address into the switch’s RAM (use Save Changes to enter the address into the switch’s non-volatile RAM). Click Start to initiate the file transfer.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 7-48. Switch History window The switch can record event information in its own logs, to designated SNMP trap receiving stations, and to the PC connected to the console manager. Clicking Next at the bottom of the window will allow you to display all the switch Trap Logs. The information is described as follows: • Sequence – A counter incremented whenever an entry to the switch’s history log is made.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Figure 7-49. Ping Test window Enter the IP address of the network device to be Pinged in the first field and select the number of test packets to be sent (3 is usually enough). Click Start to initiate the Ping program. Save Changes Figure 7-50. Save Configuration window To save all the changes made in the current session to the switch’s flash memory, click the Save Configuration button.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Factory Reset Figure 7-51. Factory Reset to Default Value window A remote reset returns the switch to the initial parameters set at the factory. Click Reset to Factory Default to reset the switch. Restart System Figure 7-52. Restart System window To perform a reboot of the switch, which resets the system, click the Restart button.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Connection Timeout Figure 7-53. Web Timeout Setup window To use this Web timeout feature, enter the desired age-out time and then click Apply. Logout Figure 7-54. Logout Web Setups window To exit the setup pages and return to the main page, click Apply. Help Click this button to access the online help files for the switch.
DGS-3224TG Gigabit Ethernet Switch User’s Guide A T ECHNICAL S PECIFICATIONS General Standards: IEEE 802.3 10BASE-T Ethernet IEEE 802.3u 100BASE-TX Fast Ethernet IEEE 802.3z Gigabit Ethernet IEEE 802.1Q Tagged VLAN IEEE 802.1P Tagged Packets IEEE 802.3ab 1000BASE-T IEEE 802.3x Full-duplex Flow Control ANSI/IEEE 802.
DGS-3224TG Gigabit Ethernet Switch User’s Guide General meters max.) 9µm Single-mode Fiber-optics (10 km max.
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DGS-3224TG Gigabit Ethernet Switch User’s Guide B C ABLE L ENGTHS Use the following table to as a guide for the maximum cable lengths: Standard GBIC 1000BASE-T 100BASE-TX 10BASE-T Media Type 50/125µm Multimode Fiber 62.
DGS-3224TG Gigabit Ethernet Switch User’s Guide C R UNTIME S WITCHING S OFTWARE D EFAULT S ETTINGS Load mode Configuration update Firmware update Out-of-band baud rate RS232 mode IP address Subnet mask Default gateway BootP service TFTP server IP address Auto log-out User name Password MAC address aging time IGMP snooping Switch GVRP Telnet status Web status Device STP Port STP Port enable Scheduling mechanism for COS queues Trunk load sharing algorithm Bridge max age Bridge hello time Bridge forward delay
DGS-3224TG Gigabit Ethernet Switch User’s Guide D U NDERSTANDING AND T ROUBLESHOOTING THE S PANNING T REE P ROTOCOL When the spanning-tree algorithm determines a port should be transitioned to the forwarding state, the following occurs: • The port is put into the listening state where it receives BPDUs and passes them to the switch’s CPU. BPDU packets from the CPU are processed.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Listening State The listening state is the first transition for a port from the blocking state. Listening is an opportunity for the switch to receive BPDUs that may tell the switch that the port should not continue to transition to the forwarding state, but should return to the blocking state (that is, a different port is a better choice). There is no address learning or packet forwarding from a port in the listening state.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Learning State A port in the learning state prepares to participate in frame forwarding. The port enters the learning state from the listening state. A port in the learning state does the following: • Discards frames received from the network segment to which it is attached. • Discards packets sent from another port on the switch for forwarding. • Adds addresses to its forwarding database. • Receives BPDUs and directs them to the CPU.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Forwarding State A port in the forwarding state forwards packets. The port enters the forwarding state from the learning state when the forward delay timer expires. A port in the forwarding state does the following: • Forwards packets received from the network segment to which it is attached. • Forwards packets sent from another port on the switch for forwarding. • Incorporates station location information into its address database.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Disabled State A port in the disabled state does not participate in frame forwarding or STP. A port in the disabled state is virtually non-operational. A disabled port does the following: • Discards packets received from the network segment to which it is attached. • Discards packets sent from another port on the switch for forwarding. • Does not add addresses to its forwarding database. • Receives BPDUs, but does not direct them to the system CPU.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Troubleshooting STP Spanning Tree Protocol Failure A failure in the STA generally leads to a bridging loop. A bridging loop in an STP environment comes from a port that should be in the blocking state, but is forwarding packets.
DGS-3224TG Gigabit Ethernet Switch User’s Guide In this example, B has been elected as the designated bridge and port 2 on C is in the blocking state. The election of B as the designated bridge is determined by the exchange of BPDUs between B and C. B had a better BPDU than C. B continues sending BPDUs advertising its superiority over the other bridges on this LAN.
DGS-3224TG Gigabit Ethernet Switch User’s Guide In the above example, port 1 on B is configured as a full-duplex port and port 1 on A is either configured as a half-duplex port, or left in auto-negotiation mode. Because port 1 on B is configured as a full-duplex port, it does not do the carrier sense when accessing the link. B will then start sending packets even if A is using the link. A will then detect collisions and begin to run the flow control algorithm.
DGS-3224TG Gigabit Ethernet Switch User’s Guide state. If the failure exists at boot, STP will not converge and rebooting the bridges will have no effect. (Note: Rebooting would help temporarily in the previous example). This type of failure is difficult to detect because the Link-state LEDs for Ethernet links rely on the transmit side of the cable to detect a link.
DGS-3224TG Gigabit Ethernet Switch User’s Guide Although the STP can elect a root bridge, a well-designed network will have an identifiable root for each VLAN. Careful setup of the STP parameters will lead to the selection of this best switch as the root for each VLAN. Redundant links can then be built into the network. STP is well suited to maintaining connectivity in the event of a device failure or removal, but is poorly suited to designing networks. Know which links are redundant.
DGS-3224TG Gigabit Ethernet Switch User’s Guide In this example, the VLAN definitions are extended to switches A and B. This gives only a single blocked port per VLAN and allows the removal of all redundant links by removing switch A or B from the network.
DGS-3224TG Gigabit Ethernet Switch User’s Guide E B RIEF R EVIEW OF B ITWISE L OGICAL O PERATIONS AND The logical AND operation compares 2 bits and if they are both “1”, then the result is “1”, otherwise, the result is “0”. 0 1 0 1 0 0 0 1 OR The logical OR operation compares 2 bits and if either or both bits are otherwise, the result is “0”.
DGS-3224TG Gigabit Ethernet Switch User’s Guide I NDEX End Node .................................................................9 A F AC inputs ............................................................ 125 AC power cord ........................................................ 4 Access Rights read only ............................................................ 68 read/write ........................................................... 68 Accessory pack ................................................
DGS-3224TG Gigabit Ethernet Switch User’s Guide P subnet mask .....................................................40, 81 password ............................................................... 30 Port Mirroring ....................................................... 55 Port Priority..................................................... 20, 45 ports......................................................................... 2 Power ......................................................................
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