3Com 3848 Implementation Guide

3Com 3848 - SuperStack 3 Switch Manual

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  • 3Com 3848 | Implementation Guide - Page 1
    SuperStack® 3 Switch 3812, Switch 3824 and Switch 3848 Implementation Guide 3C17401 3C17400 3CR17402-91 http://www.3com.com/ Part No. DUA1740-0BAA02 Published September 2004
  • 3Com 3848 | Implementation Guide - Page 2
    provided in 3Com's standard commercial license for the Software. Technical data Guide. Unless otherwise indicated, 3Com registered trademarks are registered in the United States and may or may not be registered in other countries. 3Com, SuperStack and the 3Com logo are registered trademarks of 3Com
  • 3Com 3848 | Implementation Guide - Page 3
    Save and Restore 17 Multicast Filtering 18 Rapid Spanning Tree Protocol 18 Switch Database 19 Traffic Prioritization 19 Rate Limiting 19 RMON 20 Broadcast Storm Control 20 VLANs 20 Automatic IP Configuration 20 Port Security 21 2 OPTIMIZING BANDWIDTH Port Features 23 Duplex 23 Flow Control 24 Auto
  • 3Com 3848 | Implementation Guide - Page 4
    40 Rapid Spanning Tree Protocol (RSTP) 40 What is STP? 41 How STP Works 43 STP Requirements 43 STP Calculation 43 STP Configuration 44 STP Reconfiguration 44 How RSTP Differs to STP 45 STP Example 45 STP Configurations 46 Using STP on a Network with Multiple VLANs 48 5 USING THE SWITCH DATABASE What
  • 3Com 3848 | Implementation Guide - Page 5
    Benefits of VLANs 64 VLANs and Your Switch 65 The Default VLAN 65 Communication Between VLANs 66 Creating New VLANs 66 VLANs: Tagged and Untagged Membership 66 VLAN Configuration Examples 67 Using Untagged Connections 67 Using 802.1Q Tagged Connections 68 9 USING AUTOMATIC IP CONFIGURATION How Your
  • 3Com 3848 | Implementation Guide - Page 6
    85 Configuration Rules for Fast Ethernet 86 Configuration Rules with Full Duplex 87 B NETWORK CONFIGURATION EXAMPLES Simple Network Configuration Examples 90 Desktop Switch Example 90 C IP ADDRESSING IP Addresses 91 Simple Overview 91 Advanced Overview 92 Subnets and Subnet Masks 94 Default Gateways
  • 3Com 3848 | Implementation Guide - Page 7
    GLOSSARY INDEX
  • 3Com 3848 | Implementation Guide - Page 8
  • 3Com 3848 | Implementation Guide - Page 9
    ABOUT THIS GUIDE This guide describes the features of the following Switches: ■ 3Com® SuperStack® 3 Switch 3812 (3C17401) ■ 3Com® SuperStack® 3 Switch 3824 (3C17400) ■ 3Com® SuperStack® 3 Switch 3848 (3CR17402-91) It outlines how to use these features to optimize the performance of your network. The
  • 3Com 3848 | Implementation Guide - Page 10
    10 ABOUT THIS GUIDE Most user guides and release notes are available in Adobe Acrobat Reader Portable Document Format (PDF) or HTML on the 3Com World Wide Web site: http://www.3com.com/
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    bridge port detail When you see the word "enter" in this guide, you must type something, and then press Return or Enter. Do not press Return or Enter when an instruction simply ■ Identify menu names, menu commands, and software button names. Examples: From the Help menu, select Contents. Click OK.
  • 3Com 3848 | Implementation Guide - Page 12
    Switch 3824, and Switch 3848 Getting Started Guide This guide contains: ■ all the information you need to install and set up the Switch in its default state ■ information on how to access the management software to begin managing your Switch. ■ SuperStack 3 Switch 3812, Switch 3824, and Switch 3848
  • 3Com 3848 | Implementation Guide - Page 13
    ) Example: ■ SuperStack 3 Switch 3812, Switch 3824, and Switch 3848 Implementation Guide ■ Part number: DUA1740-0BAA02 ■ Page 12 Please note that we can only respond to comments and questions about 3Com product documentation at this e-mail address. Questions related to technical support or sales
  • 3Com 3848 | Implementation Guide - Page 14
    14 ABOUT THIS GUIDE
  • 3Com 3848 | Implementation Guide - Page 15
    Guide supplied in HTML format on the CD-ROM that accompanies your Switch. Your Switch can operate in its default state. However, to make full use of the features offered by the Switch, and to change and monitor the way it works, you have to access the management software that resides on the Switch
  • 3Com 3848 | Implementation Guide - Page 16
    management software provides you with the capability to change the default state of some of the Switch features. This section provides a brief overview of these features - their applications are explained in more detail later in this guide. For a list of the features supported by your Switch, please
  • 3Com 3848 | Implementation Guide - Page 17
    access level to be able to save and restore the Switch configuration. Important Considerations ■ 3Com recommends the Switch unit is reset to its factory default settings before you restore a configuration onto it. You can reset the Switch using the system control initialize CLI command or the
  • 3Com 3848 | Implementation Guide - Page 18
    effort" restore of the configuration. For example, LACP automatic aggregations with manually defined ports are restored as manual aggregations with manual ports. LACP automatic aggregations with automatic ports where the aggregated link is disabled and Spanning Tree Protocol is disabled are restored
  • 3Com 3848 | Implementation Guide - Page 19
    STP (Spanning Tree Protocol) and is fully compatible with STP systems. RSTP can restore a network connection quicker than the legacy STP feature. RSTP can detect if it is connected to a legacy device that only supports IEEE 802.1D STP and will automatically downgrade to STP on that particular port
  • 3Com 3848 | Implementation Guide - Page 20
    ■ Usage groups For more information about VLANs, see Chapter 8 "Setting Up Virtual LANs". Automatic IP Your Switch can have its IP information automatically configured using a Configuration DHCP server. Alternatively, you can manually configure the IP information. For more information about how
  • 3Com 3848 | Implementation Guide - Page 21
    can be learned on individual ports. ■ Network Login Connections are only allowed on a port once the client has been authenticated by a RADIUS server. The maximum number of permanent addresses on the Switch is 1000. For more information about how the automatic IP configuration feature works, see
  • 3Com 3848 | Implementation Guide - Page 22
    22 CHAPTER 1: SWITCH FEATURES OVERVIEW
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    that you require to manage the Switch please refer to the Management Interface Reference Guide supplied in HTML format on the CD-ROM that accompanies your Switch. Port Features The default state for all the features detailed below provides the best configuration for most users. In normal operation
  • 3Com 3848 | Implementation Guide - Page 24
    the devices at either end of a link do not support auto-negotiation, both ends must be manually set to full duplex or half duplex accordingly. Ports operating at 1000 Mbps support full duplex mode only. Flow Control All Switch ports support flow control, which is a mechanism that prevents packet
  • 3Com 3848 | Implementation Guide - Page 25
    link is broken, the other link will still pass traffic. The Switch 3812 and Switch 3824 support a maximum of 12 aggregated links; the Switch 3848 supports a maximum of 32. Your Switch supports aggregated links on the 10/100/1000 and SFP ports. An aggregation can be created by using two 10/100/1000
  • 3Com 3848 | Implementation Guide - Page 26
    Flows B A Switch Y Z Switch X X X B0 Physical Link 1 YA X B1 Physical Link 2 Aggregated Link The key benefits of 802.3ad link aggregation are: ■ Automatic configuration - Network management does not need to be used to manually aggregate links. ■ Rapid configuration and reconfiguration
  • 3Com 3848 | Implementation Guide - Page 27
    link (either manually or via LACP) it will adopt the configuration settings of the aggregated link. When a port leaves an aggregated link its original configuration settings are restored. ■ You Switch a single aggregated link comprising both 10/100/1000 ports, both SFP ports or one SFP port and one
  • 3Com 3848 | Implementation Guide - Page 28
    all the links, except one - if you do not, a loop may be created. ■ When manually creating an aggregated link between two devices, the ports in the aggregated link must not be physically connected together until the aggregated link has been correctly configured at both ends of the link. Failure to
  • 3Com 3848 | Implementation Guide - Page 29
    Figure 3 A 2 Gbps aggregated link between two Switch units To manually set up this configuration on a Switch 3848: 1 Prepare ports 5 and 7 on the core Switch for aggregated links. To do this: a Check that the ports have an identical configuration using your preferred management interface. b Add the
  • 3Com 3848 | Implementation Guide - Page 30
    with jumbo frames. ■ The software generating the traffic must be configured so that it only sends jumbo frames to devices capable of accepting them. Jumbo Frames - Figure 4 shows a simple network with four servers connected to a switch Simple Network supporting jumbo frames. Clients are connected
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    the network shown in Figure 4 1 Connect the servers to a jumbo frames compliant switch. In this example a Switch 3812 has been used. 2 Turn on the jumbo frames support for this switch. 3 Configure the servers connected to the switch to use jumbo frames to communicate with each other. CAUTION: The
  • 3Com 3848 | Implementation Guide - Page 32
    32 CHAPTER 2: OPTIMIZING BANDWIDTH
  • 3Com 3848 | Implementation Guide - Page 33
    Interface Reference Guide supplied in HTML format on the CD-ROM that accompanies your Switch. A multicast is a packet that is intended for "one-to-many" and "manyto-many" communication. Users explicitly request to participate in the communication by joining an endstation to a specific multicast
  • 3Com 3848 | Implementation Guide - Page 34
    address in the destination address field of the packet's IP header. Benefits of Multicast The benefits of using IP with other IP protocols and services, such as Quality of Service (QoS). specific multicast groups. With multicast filtering, network devices only forward multicast traffic to the ports
  • 3Com 3848 | Implementation Guide - Page 35
    and an IGMP device, typically a router, to find out the ports that wish to join a multicast group and then sets its filters accordingly Your Switch is compatible with any device that conforms to the IGMP v2 protocol. The Switch does not support IGMP v3. If you have an IGMP v3 network, you should
  • 3Com 3848 | Implementation Guide - Page 36
    than one IP router, then the one with the lowest IP address becomes the querier. 2 When an IP endstation receives a query packet, it sends a report packet back that identifies the multicast group that the endstation would like to join. 3 When the report packet arrives at a port on a Switch with IGMP
  • 3Com 3848 | Implementation Guide - Page 37
    report of the IP multicast groups that they wish to join or to which they already belong. The querier is always the device with the lowest IP address in the subnetwork. It can be a router or a Layer 2 switch. The network no longer exist and it prunes the interface for that source-group spanning tree.
  • 3Com 3848 | Implementation Guide - Page 38
    transmission for a specific group (perhaps by clicking a Go or Start button on the client interface tree. Role of IGMP in IP Multicast Filtering To further refine the IP multicast delivery process and maximize bandwidth efficiency, a Layer 3 module filters IP multicast packets on appropriate ports
  • 3Com 3848 | Implementation Guide - Page 39
    network downtime to a minimum. The Switch provides resilient links using the Rapid Spanning Tree Protocol (RSTP). The protocol configures itself automatically based on the surrounding network and is compatible with switches that use either the Spanning Tree Protocol (STP) or RSTP. For detailed
  • 3Com 3848 | Implementation Guide - Page 40
    .1w-2001. Some of the benefits of RSTP are: ■ Faster determination of the Active Spanning Tree topology throughout a bridged network. ■ Support for bridges with more than 256 ports. ■ Support for the Fast-Forwarding configuration of edge ports provided by the 'Fast Start' feature. Fast Start allows
  • 3Com 3848 | Implementation Guide - Page 41
    ports on a Switch to operate in RSTP (802.1w) mode, and other ports, for example those connected to a legacy Switch, to operate in STP (802.1D) mode. ■ you have an option to force your Switch to use the legacy 802.1D version of Spanning Tree traffic, so this configuration will work satisfactorily.
  • 3Com 3848 | Implementation Guide - Page 42
    2 flows through Bridge B. Figure 8 Traffic flowing through Bridge B STP determines which is the most efficient path between each bridged segment and a specifically assigned reference point on the network. Once the most efficient path has been determined, all other paths are blocked. Therefore, in
  • 3Com 3848 | Implementation Guide - Page 43
    as outlined in the sections below. STP Requirements Before it can configure the network, the STP system requires: ■ Communication between all the using the MAC address of the bridge and a priority defined for the bridge. The default priority of your Switch is 32768. ■ Each port to have a cost
  • 3Com 3848 | Implementation Guide - Page 44
    to detect the change sends out an SNMP trap. CAUTION: Network loops can occur if aggregated links are manually configured incorrectly, that is, the physical connections do not match the assignment of ports to an aggregated link. RSTP and STP may not detect these loops. So that RSTP and STP can
  • 3Com 3848 | Implementation Guide - Page 45
    which is why RSTP can carry out automatic configuration and restore a link faster than STP. STP Example Figure 9 shows a LAN that has STP enabled. The LAN has three segments, and each segment is connected using two possible links. Figure 9 Port costs in a network ■ Bridge A has the lowest Bridge
  • 3Com 3848 | Implementation Guide - Page 46
    is therefore selected as the Designated Bridge Port for LAN Segment 3. STP Configurations Figure 10 shows three possible STP configurations using SuperStack 3 Switch units. ■ Configuration 1 - Redundancy for Backbone Link In this configuration, the Switches both have STP enabled and are connected
  • 3Com 3848 | Implementation Guide - Page 47
    Figure 10 STP configurations 1 Switch Block 2 Switch How STP Works 47 Switch Block Block Switch Switch 3 Block 10Mbps Hub
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    VLAN configuration on your network takes into account the expected STP topology and alternative topologies that may result from link failures. For example, Figure 11 shows a network containing VLANs 1 and 2. They are connected using the 802.1Q-tagged link between Switch B and Switch C. By default
  • 3Com 3848 | Implementation Guide - Page 49
    to the Switch. ■ Port identifier, that is the port attached to the endstation that is sending the packet. ■ VLAN ID of the VLAN to which the endstation belongs. For details of the number of addresses supported by your Switch database, please refer to Chapter 1 of the Getting Started Guide that
  • 3Com 3848 | Implementation Guide - Page 50
    by ensuring that when an endstation is removed from the network, its entry is also removed from the database. ■ Learned entries are removed from the Switch Database if the Switch is reset or powered-down. ■ Non-aging learned - If the aging time is set to 0 seconds, all learned entries in the
  • 3Com 3848 | Implementation Guide - Page 51
    Your Switch has Port" on page 57. Traffic prioritization allows high priority data, such as time-sensitive and system-critical data to be transferred smoothly and with minimal delay over a network. Traffic prioritization is most useful for critical applications that require a high level of service
  • 3Com 3848 | Implementation Guide - Page 52
    in the service level directs the packet to the appropriate egress queue. When a packet comes in with both 802.1D and DSCP priority markings, the higher of the priorities will be used. Configuring traffic prioritization for CoS Switch QoS can be configured on your Switch using the 3Com Network
  • 3Com 3848 | Implementation Guide - Page 53
    Guide supplied in HTML format on the CD-ROM that accompanies your Switch. Configure Class of Service using 3Com Network service levels. 4 Apply CoS profile After a CoS profile has been created, it can be assigned to the Port(s). When the profile is assigned to the port(s), the QoS configuration
  • 3Com 3848 | Implementation Guide - Page 54
    is able to carry VLAN identification and user priority information. The information is carried in a header field immediately following the destination MAC address, and Source MAC address. 802.1D Priority Levels The traffic prioritization feature supported by the Switch at layer 2 is compatible with
  • 3Com 3848 | Implementation Guide - Page 55
    Ingress Port Switch Traffic Classification 802.1D Service supported traffic queues. DiffServ traffic classification DiffServ is an alternative method of classifying traffic so that different levels of service can be applied to it on a network. DiffServ is a layer 3 function; and the service
  • 3Com 3848 | Implementation Guide - Page 56
    13 illustrates how DiffServ code point (DSCP) service levels are mapped to the eight Traffic Queues. IP Port traffic The Switch supports classification of traffic from legacy devices by classification classifying traffic by its IP port number. When an IP packet is transmitted it is always tagged
  • 3Com 3848 | Implementation Guide - Page 57
    the Rate of a Port 57 The Switch uses the following queuing mechanisms: ■ Weighted Round Robin (WRR) - This method services all the traffic queues is the default method. ■ Strict Priority Queuing (SPQ) - This method guarantees that traffic on a higher priority queue will always be serviced ahead of
  • 3Com 3848 | Implementation Guide - Page 58
    are best used together if the egress rate rather than the ingress rate is limited on a port; the traffic rate leaving the Switch is limited rather than the traffic arriving at the Switch. This ensures that the traffic is prioritized before rate limiting is applied and the lowest priority packets
  • 3Com 3848 | Implementation Guide - Page 59
    Switch please refer to the Management Interface Reference Guide supplied in HTML format on the CD-ROM that accompanies your Switch. Using the RMON capabilities of a Switch VLANs. RMON is an integrated part of the Switch software agent and continually collects statistics about a LAN segment or VLAN,
  • 3Com 3848 | Implementation Guide - Page 60
    This section describes the four groups supported by the Switch, and details how you can use patterns and trends on a LAN segment or VLAN, and for establishing the normal operating parameters of are used to inform you of network performance problems and they can trigger automated responses through the
  • 3Com 3848 | Implementation Guide - Page 61
    is detailed in Table 4. Table 4 RMON support supplied by the Switch RMON group Statistics History Support supplied by the Switch A new or initialized Switch has one Statistics session per port. A new or initialized Switch has two History sessions per port. These sessions provide the data for the
  • 3Com 3848 | Implementation Guide - Page 62
    62 CHAPTER 7: STATUS MONITORING AND STATISTICS Table 4 RMON support supplied by the Switch RMON group Alarms Events Support supplied by the Switch A new or initialized Switch has two Alarm sessions per port For more information about the alarms setup on the Switch, see "Alarm Events" on page 62.
  • 3Com 3848 | Implementation Guide - Page 63
    What are VLANs? ■ Benefits of VLANs ■ VLANs and Your Switch ■ VLAN Configuration Examples For detailed descriptions of the Web interface operations and the Command Line Interface (CLI) commands that you require to manage the Switch please refer to the Management Interface Reference Guide supplied in
  • 3Com 3848 | Implementation Guide - Page 64
    dealing with moves and changes. If users move to a different subnetwork, the addresses of each endstation must be updated manually. With a VLAN setup, if an endstation in VLAN Marketing for example is moved to a port in another part of the network, and retains its original subnet membership, you
  • 3Com 3848 | Implementation Guide - Page 65
    Switch contains a single VLAN, the Default VLAN. This VLAN has the following definition: ■ VLAN Name - Default VLAN ■ 802.1Q VLAN ID - 1 (if tagging required) All the ports are initially placed in this VLAN, and it is the only VLAN that allows you to access the management software of the Switch
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    Layer 3 Switch and redirected to ports in VLAN Marketing. Router or Layer 3 Switch Creating New VLANs If you want to move a port from the Default VLAN to another VLAN, you must first define information about the new VLAN on your Switch. VLANs: Tagged and Untagged Membership Your Switch supports
  • 3Com 3848 | Implementation Guide - Page 67
    can identify which packets belong in which VLANs. To communicate between VLANs a router must be used. VLAN Configuration Examples This section contains examples of VLAN configurations. It describes how to set up your Switch to support simple untagged and tagged connections. Using Untagged
  • 3Com 3848 | Implementation Guide - Page 68
    in Figure 16: 1 Configure the VLANs Define VLAN 2 on the Switch. VLAN 1 is the default VLAN and already exists. 2 Add ports to the VLANs Add ports 10, 11 and 12 of the Switch as untagged members to VLAN 2. You can use the Switch Web Interface to change VLAN configuration. VLAN configuration can be
  • 3Com 3848 | Implementation Guide - Page 69
    link to Switch 2. 4 Configure the VLANs on Switch 2 Define VLAN 2. VLAN 1 is the default VLAN and already exists. 5 Add endstation ports on Switch 2 to the VLANs Place the endstation ports in the appropriate VLANs as untagged members. 6 Add port 11 on Switch 2 to the VLANs Add port 11 on Switch 2 as
  • 3Com 3848 | Implementation Guide - Page 70
    70 CHAPTER 8: SETTING UP VIRTUAL LANS 7 Check the VLAN membership for both Switches The relevant ports should be listed in the VLAN members summary. 8 Connect the Switches Connect port 12 on Switch 1 to port 11 on Switch 2. The VLANs are now configured and operational and the endstations in both
  • 3Com 3848 | Implementation Guide - Page 71
    IP addresses and how the automatic configuration option works. It covers the following topics: ■ How Your Switch Obtains IP Information ■ How Automatic IP Configuration Works ■ Important Considerations For detailed information on setting up your Switch for management, see the Getting Started Guide
  • 3Com 3848 | Implementation Guide - Page 72
    ways to obtain its IP address information: ■ Automatic IP Configuration (default) - The Switch attempts to configure itself by communicating with a DHCP server on the network. ■ Manual IP Configuration - You can manually input the IP information (IP address, subnet mask, and default gateway). If you
  • 3Com 3848 | Implementation Guide - Page 73
    contains some important points to note when using the automatic IP configuration feature. The dynamic nature of automatically configured IP information means that a Switch may change its IP address whilst in use. Server Support Your Switch has been tested to interoperate with DHCP servers that use
  • 3Com 3848 | Implementation Guide - Page 74
    74 CHAPTER 9: USING AUTOMATIC IP CONFIGURATION
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    using the Secure Sockets Layer (SSL) of HTTP. If your network traffic is intercepted, no passwords or configuration information will be visible in the data. To use HTTPS you need the following: ■ A browser that supports SSL ■ A digital certificate installed on the Switch The Switch generates its own
  • 3Com 3848 | Implementation Guide - Page 76
    /SSH client. You do not need a digital certificate as your Switch can generate its own. To administer your Switch using SSH, start your Telnet/SSH client and enter the IP address of your Switch. If your Telnet/SSH application supports both encrypted and unencrypted modes, make sure that you have SSH
  • 3Com 3848 | Implementation Guide - Page 77
    speed using layer 3 destination IP addresses and VLANs. How Access Control List Rules Work IP addresses and are defined by the destination IP address and a mask. If a match is found in the access list the appropriate action is taken. By default, if no access list has been defined for a VLAN, all IP
  • 3Com 3848 | Implementation Guide - Page 78
    Your Switch supports the following port security modes, which you can set for an individual port or a range of ports: ■ No Security Port security is disabled and all network traffic is forwarded through the port without any restrictions. ■ Learning Off All currently learnt addresses on the port are
  • 3Com 3848 | Implementation Guide - Page 79
    to the Switch port. In addition to providing protection against unauthorized network access, Network Login also allows the user of a port to be identified. This user identification information can be used for service accounting or billing, or to help network administrators resolve problems. Network
  • 3Com 3848 | Implementation Guide - Page 80
    Switch receives either an authentication succeeded or failed message from the server, and then configures the port to forward or filter traffic as appropriate. If access is granted, the Spanning Tree Protocol places the port into the forwarding state and the client device can obtain an IP address
  • 3Com 3848 | Implementation Guide - Page 81
    Some client devices that are connected to the Switch port may not support the authentication service, for example printers. You should configure the Switch port to operate in Automatic Learning mode, so that network traffic that does not match the MAC address for the client device is filtered. ■ You
  • 3Com 3848 | Implementation Guide - Page 82
    is enabled, the network administrator must have local access to each Switch to securely change user name and password information. This can be time consuming, tedious and often results in bad configurations and lapses in security. RADIUS authentication provides centralized, secure access and
  • 3Com 3848 | Implementation Guide - Page 83
    . ■ Before you enable RADIUS authentication you must ensure that: ■ The Switch is configured with a static IP address. ■ RADIUS has been configured on the Switch. ■ The RADIUS server in your network is operational. ■ If the Switch is unable to contact the RADIUS server, the Command Line Interface
  • 3Com 3848 | Implementation Guide - Page 84
    84 CHAPTER 10: MAKING YOUR NETWORK SECURE
  • 3Com 3848 | Implementation Guide - Page 85
    CONFIGURATION RULES Configuration The different types of Gigabit Ethernet media and their specifications are detailed in Table 6. Table 6 Gigabit Ethernet 500 400 500 N/A 160 120 400 500 N/A Lengths Supported Specified by IEEE (meters) 2-550 2-550 2-550 2-5000 2-220 2-275 2-500 2-550 100
  • 3Com 3848 | Implementation Guide - Page 86
    86 APPENDIX A: CONFIGURATION RULES Configuration Rules for Fast Ethernet The topology rules and provides examples of how they allow for large-scale Fast Ethernet networks. Figure 20 Fast Ethernet configuration rules The key topology rules are: ■ Maximum UTP cable length is 100 m (328 ft) over
  • 3Com 3848 | Implementation Guide - Page 87
    example, a 225 m (738 ft) fiber link from a repeater to a router or switch, plus a 100 m (328 ft) UTP link from a repeater out to the endstations. Configuration Rules The Switch provides full duplex support for all its ports. Full duplex allows with Full Duplex packets to be transmitted and received
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    88 APPENDIX A: CONFIGURATION RULES
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    B NETWORK CONFIGURATION EXAMPLES This chapter contains the following section: ■ Simple Network Configuration Examples ■ Desktop Switch Example
  • 3Com 3848 | Implementation Guide - Page 90
    B: NETWORK CONFIGURATION EXAMPLES Simple Network Configuration Examples The following illustrations show some simple examples of how the Switch 3812, Switch 3824, or Switch 3848 can be used in your network. Desktop Switch The example in Figure 21 shows how a Switch 3848 and a Switch 4200 Example
  • 3Com 3848 | Implementation Guide - Page 91
    This chapter provides some background detail on the IP information that needs to be assigned to your Switch to enable you to manage it across a network. The topics covered are: ■ IP Addresses ■ Subnets and Subnet Masks ■ Default Gateways IP addressing is a vast topic and there are white papers
  • 3Com 3848 | Implementation Guide - Page 92
    parts depends on the class of IP network. IP addresses differ from Ethernet MAC addresses, which are unique hardware-configured 48-bit addresses. A central agency, such as the InterNIC Registration Services mentioned above, assigns the network part of the IP address, and you assign the host part
  • 3Com 3848 | Implementation Guide - Page 93
    network part and the host part depends on the class that the central agency assigns to your network. The three primary classes of IP addresses are as follows: ■ Class A address - Uses 8 bits for the network part and 24 bits for the host part. Although only a few Class A networks can be created, each
  • 3Com 3848 | Implementation Guide - Page 94
    Subnets and Subnet Masks You can divide your IP network into sub-networks also known as subnets. Support for subnets is important because the number of bits assigned to the device part of an IP address limits the number of devices that may be addressed on any given network. For example, a Class
  • 3Com 3848 | Implementation Guide - Page 95
    the host number, as shown in Figure 25. Figure 25 Extending the Network Prefix Take the IP address IP address Network Subnet and Host Apply the subnet mask Subnet mask 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Many Internet Service Providers (ISPs) now use this notation to denote the subnet mask. See Table
  • 3Com 3848 | Implementation Guide - Page 96
    . This hop-by-hop process continues until the IP packets reach the remote destination. If manually configuring IP information for the Switch, enter the IP address of the default gateway on the local subnet in which the Switch is located. If no default gateway exists on your network, enter the
  • 3Com 3848 | Implementation Guide - Page 97
    a group of ports to carry traffic between the switches. auto-negotiation A feature on twisted pair ports that allows them to advertise their capabilities for speed, duplex and flow control. When connected to a port that also supports auto-negotiation, the link can automatically configure itself to
  • 3Com 3848 | Implementation Guide - Page 98
    Ethernet operation, but a sudden prolonged increase in the number of collisions can indicate a problem with a device, particularly if it is not accompanied by a general increase in traffic centrally manage and automate the assignment of Internet Protocol (IP) addresses in an organization's network.
  • 3Com 3848 | Implementation Guide - Page 99
    , instead of its IP address. endstation A computer, printer or server that is connected to a network. Ethernet A LAN specification developed jointly by Xerox is caused when devices send traffic to an already overloaded port on a Switch. Flow control prevents packet loss by inhibiting devices from
  • 3Com 3848 | Implementation Guide - Page 100
    802.1D, 1998 Edition. IEEE Std 802.1Q-1998 A standard that defines VLAN tagging. IEEE Std 802.3ad A standard that defines link aggregation. 802.3ad is standard that defines Rapid Spanning Tree Protocol (RSTP) behavior. IEEE Std 802.1X-2001 A standard that defines port-based network access control
  • 3Com 3848 | Implementation Guide - Page 101
    of protocols that describe the routing of packets to addressed devices. IPX Internetwork Packet Exchange. IPX is a layer 3 and 4 network protocol designed for networks that use Novell® Netware®. IP address Internet Protocol address. A unique identifier for a device attached to a network using TCP
  • 3Com 3848 | Implementation Guide - Page 102
    used by the Simple Network Management Protocol (SNMP) to gather information about the devices on a network. The Switch contains its own internal MIB. multicast A packet sent to a specific group of endstations on a network. multicast filtering A system that allows a network device to only forward
  • 3Com 3848 | Implementation Guide - Page 103
    monitor LANs by addressing up to nine different groups of information. router A router is a device on your network which is used to forward IP packets to a remote destination. An alternative name for a router is a gateway. RSTP See Rapid Spanning Tree Protocol. SAP Service Access Point. A well
  • 3Com 3848 | Implementation Guide - Page 104
    network services such as port in the link fails. STP See Spanning Tree Protocol (STP). subnet mask A subnet mask is used to divide the device part of the IP address into two further parts. The first part identifies the subnet number. The second part identifies the device on that subnet. switch
  • 3Com 3848 | Implementation Guide - Page 105
    , as well as the address of the destination network. Telnet A TCP/IP application protocol that provides a virtual terminal service, letting a user log forwarded through a switch without being obstructed by other data. unicast A packet sent to a single endstation on a network. VLAN Virtual LAN. A
  • 3Com 3848 | Implementation Guide - Page 106
    106 GLOSSARY
  • 3Com 3848 | Implementation Guide - Page 107
    notice icons, About This Guide 11 text, About This Guide 11 CoS configuring traffic 52 creating profiles 53 How traffic is processed to provide CoS 52 service levels 53 INDEX 107 traffic classification 53 D default gateway 96 Default VLAN 65 Designated Bridge 44 Designated Bridge Port 44 E event
  • 3Com 3848 | Implementation Guide - Page 108
    33 N network addresses 91 security 75 network configuration examples 90 network login 78 non-aging learned SDB entries 50 O obtaining registered IP address 92 P path costs. See port costs permanent SDB entries 50 port costs, default 43 port security 21, 75, 78 port trunks example 29 priority
  • 3Com 3848 | Implementation Guide - Page 109
    94 sub-networks. See subnets Switch Database 49 switch management login 75 T topology rules for Fast Ethernet 86 topology rules with full duplex 87 traffic classification 802.1D 54 traffic prioritization 19, 51 802.1D 54 queues 56 V VLANs 63 benefits 64 Default 65 defining the information for 66
  • 3Com 3848 | Implementation Guide - Page 110
    110 INDEX
  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 8
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Part No. DUA1740-0BAA02
Published September 2004
SuperStack
®
3 Switch 3812, Switch 3824 and
Switch 3848
Implementation Guide
3C17401
3C17400
3CR17402-91