Related Manuals for 3Com 3824
Summary of Contents for 3Com 3824
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Page 1: Switch 3812 And Switch 3824
Switch 3812 and Switch 3824 Implementation Guide 3C17401, 3C17400 http://www.3com.com/ Part No. DUA1740-0BAA01 Published May 2003... - Page 2 3Com Corporation reserves the right to revise this documentation and to make changes in content from time California 95052-8145 to time without obligation on the part of 3Com Corporation to provide notification of such revision or change. 3Com Corporation provides this documentation without warranty, term, or condition of any kind, either implied or expressed, including, but not limited to, the implied warranties, terms or conditions of merchantability, satisfactory quality, and fitness for a particular purpose.
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Page 3: Table Of Contents
ONTENTS BOUT UIDE Conventions Related Documentation Documentation Comments Product Registration WITCH EATURES What is Management Software? Switch Features Explained Automatic IP Configuration Port Security Aggregated Links Auto-negotiation Multicast Filtering Spanning Tree Protocol and Rapid Spanning Tree Protocol Switch Database Traffic Prioritization RMON Broadcast Storm Control VLANs... - Page 4 Aggregated Links and Your Switch Aggregated Link — Manual Configuration Example SING ULTICAST What is an IP Multicast? Benefits of Multicast Multicast Filtering Multicast Filtering and Your Switch IGMP Multicast Filtering SING ESILIENCE Resilience Feature Overview Spanning Tree Protocol (STP) Rapid Spanning Tree Protocol (RSTP) What is STP? How STP Works...
- Page 5 Traffic Re-Marking Traffic Prioritization Traffic Queues Important QoS Considerations Default QoS Configurations TATUS ONITORING AND RMON What is RMON? The RMON Groups Benefits of RMON RMON and the Switch Alarm Events ETTING IRTUAL What are VLANs? Benefits of VLANs VLANs and Your Switch The Default VLAN Communication Between VLANs Creating New VLANs...
- Page 6 ONFIGURATION Configuration Rules for Gigabit Ethernet Configuration Rules for Fast Ethernet Configuration Rules with Full Duplex ETWORK ONFIGURATION Simple Network Configuration Examples Desktop Switch Example Advanced Network Configuration Examples Improving the Resilience of Your Network Enhancing the Performance of Your Network IP A DDRESSING IP Addresses...
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Page 7: About This Guide
Managed Gigabit) and 3Com Switch 3824 (24-port, Managed Gigabit). It outlines how to use these features to optimize the performance of your network. The term Switch 3812 and Switch 3824 is used when referring to the 3Com Switch 3812 (12-port, Managed Gigabit) and 3824 (24-port, Managed Gigabit). -
Page 8: Conventions
BOUT UIDE Conventions Table 1 Table 1 Notice Icons Table 2 Text Conventions Convention Screen displays This typeface represents information as it appears on the Syntax Commands The words “enter” and “type” Keyboard key names If you must press two or more keys simultaneously, the key Words in italics Table 2 list conventions that are used throughout this guide. -
Page 9: Related Documentation
Command Line Interface that enable you to manage the Switch. It is supplied in HTML format on the CD-ROM that accompanies the Switch. Switch 3812 and Switch 3824 Management Quick Reference Guide This guide contains: a list of the features supported by the Switch. -
Page 10: Product Registration
Product You can now register your Switch on the 3Com Web site: Registration http://www.3com.com/register/ You will need your product part number (3Cxxxxx), product serial number and date and place of purchase to register your 3Com product. -
Page 11: Switch Features
This chapter contains introductory information about the Switch 3812 and Switch 3824 management software and supported features. It covers the following topics: 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 HTML format on the CD-ROM that accompanies your Switch. -
Page 12: Automatic Ip Configuration
1: S HAPTER WITCH EATURES 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 the automatic IP configuration feature works, see Port Security Your Switch supports the following port security modes, which you can set for an individual port or a range of ports:... -
Page 13: Multicast Filtering
For details of the auto-negotiation features supported by your Switch, please refer to the Management Quick Reference Guide that accompanies your Switch. Duplex Full duplex mode allows packets to be transmitted and received simultaneously and, in effect, doubles the potential throughput of a link. Flow Control All Switch ports support flow control, which is a mechanism that minimizes packet loss during periods of congestion on the network. -
Page 14: Switch Database
1: S HAPTER WITCH EATURES RSTP is an enhanced version of the STP feature and is enabled by default. 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. -
Page 15: Broadcast Storm Control
Departmental groups Hierarchical groups Usage groups 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 System >... - Page 16 The configuration of the Switch must only be restored or saved by a single user at a time. When using the Configuration Save and Restore feature, 3Com recommends that aggregated links are configured as either: Manual aggregations with Link Aggregation Configuration Protocol (LACP) disabled on the ports that are to be manually placed in the aggregated link.
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Page 17: Optimizing Bandwidth
There are many ways you can optimize the bandwidth on your network and improve network performance. If you utilize certain Switch features you can provide the following benefits to your network and end users: 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 HTML format on the CD-ROM that accompanies your Switch. -
Page 18: Flow Control
2: O HAPTER PTIMIZING ANDWIDTH 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 loss during periods of congestion on the network. -
Page 19: Aggregated Links
Aggregated Links Aggregated links are connections that allow devices to communicate using up to eight member links in parallel. Aggregated links provide the following benefits: Figure 1 containing four member links. If all ports on both Switch units are configured as 1000BASE-TX and they are operating in full duplex, the potential maximum bandwidth of the connection is 8 Gbps. -
Page 20: Implementing 802.3Ad Aggregated Links
2: O HAPTER PTIMIZING ANDWIDTH failed — almost instantaneously. As a result, aggregated link configurations are extremely resilient and fault-tolerant. Figure 2 Dynamic Reassignment of Traffic Flows The key benefits of 802.3ad link aggregation are: Implementing LACP can be enabled or disabled on a per port basis. You can implement 802.3ad Aggregated 802.3ad aggregated links in two ways: Links... -
Page 21: Aggregated Links And Your Switch
Aggregated Links and Your Switch member of an aggregated link for Switch A in error, LACP (if it is enabled) will detect this and place the port in the aggregated link for Switch B, thus overriding the manual configuration. Figure 3 Aggregated Link — Example LACP Automatic Aggregations —... - Page 22 2: O HAPTER PTIMIZING ANDWIDTH Figure 4 How LACP works on a Switch with multiple aggregated links When setting up an aggregated link, note that: The Switch only supports a maximum of eight active ports in any individual aggregation. If multiple links are connected between a unit and more than six other devices as shown in assigned to aggregated links.
- Page 23 The member link ports can be mixed media, that is fiber and/or twisted pair ports within the same aggregated link. The member link ports must have the same configuration. Member links must retain the same groupings at both ends of an aggregated link.
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Page 24: Aggregated Link - Manual Configuration Example
2: O HAPTER PTIMIZING ANDWIDTH Traffic Distribution and Link Failure on Aggregated Links To maximize throughput, all traffic is distributed across the individual links that make up an aggregated link. Therefore, when a packet is made available for transmission down an aggregated link, a hardware-based traffic distribution mechanism determines which particular port in the link should be used. - Page 25 Figure 6 An 8 Gbps aggregated link between two Switch units To manually set up this configuration: 1 Prepare ports 2, 4, 6 and 8 on the upper Switch for aggregated links. To do this: a Check that the ports have an identical configuration using your preferred management interface.
- Page 26 2: O HAPTER PTIMIZING ANDWIDTH...
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Page 27: Using Multicast Filtering
Multicast filtering improves the performance of networks that carry multicast traffic. This chapter explains multicasts, multicast filtering, and how multicast filtering can be implemented on your Switch. It covers the following topics: 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 HTML format on the CD-ROM that accompanies your Switch. -
Page 28: Benefits Of Multicast
3: U HAPTER SING ULTICAST A multicast packet is identified by the presence of a multicast group address in the destination address field of the packet’s IP header. Benefits of Multicast The benefits of using IP multicast are that it: There are situations where a multicast approach is more logical and efficient than a unicast approach. -
Page 29: Multicast Filtering And Your Switch
IP address in the subnetwork to which it belongs. IGMP querying is disabled by default on the Switch 3812 and Switch 3824. This helps prevent interoperability issues with core products that may not follow the lowest IP address election method. -
Page 30: Igmp Multicast Filtering
Switch to automatically negotiate with compatible devices on VLAN 1 to become the querier. The Switch 3812 and Switch 3824 are compatible with any device that conforms to the IGMP v2 protocol. The Switch does not support IGMP v3. - Page 31 IGMP Multicast Filtering Enabling IGMP Multicast Learning You can enable or disable multicast learning and IGMP querying using the snoopMode command on the Web interface. For more information about enabling IGMP multicast learning, please refer to the Management Interface Reference Guide supplied on your Switch CD-ROM. If IGMP multicast learning is not enabled then IP multicast traffic is always forwarded, that is, it floods the network.
- Page 32 3: U HAPTER SING ULTICAST ILTERING...
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Page 33: Using Resilience Features
SING Setting up resilience on your network helps protect critical links against failure, protects against network loops, and reduces network downtime to a minimum. This chapter explains the features supported by the Switch that provide resilience for your network. It covers the following topics: Spanning Tree Protocol (STP) Rapid Spanning Tree Protocol (RSTP) STP feature. -
Page 34: Resilience Feature Overview
Table 3 Spanning Tree Protocols — Key Differences 3Com recommends that you use the Rapid Spanning Tree Protocol feature (default enabled) to provide optimum performance for your network and ease of use. -
Page 35: Rapid Spanning Tree Protocol (Rstp)
The protocol is a part of the IEEE Std 802.1D, 1998 Edition bridge specification. To explain STP more effectively, your Switch will be referred to as a bridge. Rapid Spanning Tree The Rapid Spanning Tree (RSTP) is an enhanced Spanning Tree feature. Protocol (RSTP) RSTP implements the Spanning Tree Algorithm and Protocol, as defined in the IEEE Std 802.1w-2001. - Page 36 4: U HAPTER SING ESILIENCE EATURES As an example, Figure 8 shows a network containing three LAN segments separated by three bridges. With this configuration, each segment can communicate with the others using two paths. Without STP enabled, this configuration creates loops that cause the network to overload. Figure 8 A network configuration that creates loops Figure 9 shows the result of enabling STP on the bridges in the...
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Page 37: How Stp Works
If a link failure is detected, as shown in reconfigures the network so that traffic from LAN segment 2 flows through Bridge B. Figure 10 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. -
Page 38: Stp Calculation
4: U HAPTER SING ESILIENCE Table 4 Default port costs Port Speed 10 Mbps 100 Mbps 1000 Mbps STP Calculation The first stage in the STP process is the calculation stage. During this stage, each bridge on the network transmits BPDUs that allow the system to work out: STP Configuration After all the bridges on the network have agreed on the identity of the... -
Page 39: Stp Reconfiguration
How STP Works bridge is configured to forward traffic only between its Root Port and the Designated Bridge Ports for the respective network segments. All other ports are blocked, which means that they are prevented from receiving or forwarding traffic. STP Reconfiguration Once the network topology is stable, all the bridges listen for Hello BPDUs transmitted from the Root Bridge at regular intervals. - Page 40 4: U HAPTER SING ESILIENCE EATURES Figure 11 Port costs in a network Bridge A has the lowest Bridge Identifier in the network, and has therefore been selected as the Root Bridge. Because Bridge A is the Root Bridge, it is also the Designated Bridge for LAN segment 1.
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Page 41: Stp Configurations
STP Configurations Figure 12 Switch units. Bridge C has been selected as the Designated Bridge for LAN segment 3, because it offers the lowest Root Path Cost for LAN Segment 3: the route through Bridges C and B costs 200 (C to B=100, B to A=100) the route through Bridges Y and B costs 300 (Y to B=200, B to A=100). - Page 42 4: U HAPTER SING ESILIENCE EATURES Figure 12 STP configurations...
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Page 43: Using Stp On A Network With Multiple Vlans
Using STP on a The IEEE Std 802.1D, 1998 Edition does not take into account VLANs Network with when it calculates STP information — the calculations are only performed Multiple VLANs on the basis of physical connections. For this reason, some network configurations can result in VLANs being subdivided into a number of isolated sections by the STP system. - Page 44 4: U HAPTER SING ESILIENCE EATURES...
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Page 45: Using The
What is the Switch The Switch Database is used by the Switch to determine where a packet Database? should be forwarded to, and which port should transmit the packet if it is to be forwarded. The database contains a list of entries — each entry contains three items: For details of the number of addresses supported by your Switch database, please refer to Chapter 1 of the Getting Started Guide that accompanies your Switch. -
Page 46: Switch Database Entry States
5: U HAPTER SING THE WITCH Switch Database Databases entries can have three states: Entry States ATABASE Learned — The Switch has placed the entry into the Switch Database when a packet was received from an endstation. Note that: Learned entries are removed (aged out) from the Switch Database if the Switch does not receive further packets from that endstation within a certain period of time (the aging time). -
Page 47: Using Traffic Prioritization
Default QoS Configurations Basic traffic prioritization is the default level of QoS supported by the Switch 3812 and Switch 3824. For a list of the features supported by your Switch, please refer to the Management Quick Reference Guide that accompanies your Switch. -
Page 48: What Is Traffic Prioritization
You can provide predictable throughput for multimedia applications such as video conferencing or voice over IP platforms like the 3Com NBX, as well as minimizing traffic delay and jitter. You can improve network performance as the amount of traffic grows, which also reduces the need to constantly add bandwidth to the network, therefore saving cost. -
Page 49: Traffic Classification
Traffic prioritization in your Switch may be applied dependent upon following factor: A QoS network can differentiate between time critical data, business critical data and opportunistic data (such as email, File Transfer Protocol (FTP) and Web traffic). A QoS network also has the ability to stop unauthorized usage of the network, such as online gaming. -
Page 50: Traffic Marking
6: U HAPTER SING RAFFIC Table 5 Attributes on which incoming traffic can be classified (identified) OSI Layer and Protocols Layer 2 Layer 3 Layer 4 Traffic Marking After traffic has been identified through classification, it must be Marked to ensure that other devices such as Layer 2 switches or routers on the network know how to prioritize the application, device or user that generated it. - Page 51 determines the level of service that type of traffic should receive. Refer to Table 6 for an example of how different traffic types can be mapped to the eight IEEE 802.1p priority levels. Table 6 IEEE recommendation for mapping 802.1p priority levels to 802.1D traffic types IEEE 802.1p IEEE 802.1D...
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Page 52: Traffic Re-Marking
IEEE 802.1Q 4-byte tag, and therefore traffic will only contain 802.1p priority markings if the network is configured with VLANs and VLAN tagging. The Switch 3812 and Switch 3824 both support basic traffic prioritization. The traffic flow through the Switch is as follows: 1 A packet received by the Switch may or may not have an 802.1p tag... - Page 53 The mapping from 802.1p level to traffic queue in the Switch is proprietary and is slightly different to the recommended IEEE mapping. Figure 14 IEEE 802.1p priority levels and recommended IEEE 802.1D traffic types Switch 3812 and Switch 3824 Traffic Classification Ingress Port 802.1D...
- Page 54 6: U HAPTER SING RAFFIC Figure 14 will check a packet received at the ingress port for IEEE 802.1D traffic classification, and then prioritize it based upon the IEEE 802.1p value (service levels) in that tag. It is this 802.1p value that determines which traffic queue the packet is mapped to.
- Page 55 Figure 15 Advanced traffic prioritization and marking Switch 3812 and Switch 3824 Service Levels Classification DSCP Ingress Port EtherType 1 The packet received at the ingress port is checked for any of the supported traffic classification methods (DSCP, Ethertype, Protocol) to identify the traffic.
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Page 56: Traffic Queues
Traffic queues cannot be enabled on a per-port basis on the Switch 3812 and Switch 3824. Important QoS Before implementing QoS on your network you need to consider the... - Page 57 Has eight traffic queues, but it is important to note that not all Switches have the same number of priority queues. QoS is about providing a consistent, predictable data delivery service. It should not be used as an alternative to deploying sufficient bandwidth.
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Page 58: Default Qos Configurations
Default QoS The Switch is pre-configured with the following settings: Configurations Table 7 Default traffic classifiers configured in your Switch RIORITIZATION Classifier Classifier Protocol Name Type Identifier 3Com NBX EtherType 0x8868 Voice-LAN 3Com NBX DSCP Voice-IP Internet DSCP Network Control Network... -
Page 59: Status Monitoring And Statistics
This chapter contains details of the Remote Monitoring (RMON) feature that assists you with status monitoring and statistics. 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 HTML format on the CD-ROM that accompanies your Switch. - Page 60 7: S HAPTER TATUS ONITORING AND TATISTICS Statistics The Statistics group provides traffic and error statistics showing packets, bytes, broadcasts, multicasts and errors on a LAN segment or VLAN. Information from the Statistics group is used to detect changes in traffic and error patterns in critical areas of your network.
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Page 61: Benefits Of Rmon
Benefits of RMON Using the RMON features of your Switch has three main advantages: RMON and the The RMON support provided by your Switch 3812 and Switch 3824 is Switch detailed in Table 8 RMON support supplied by the Switch... -
Page 62: Alarm Events
7: S HAPTER TATUS ONITORING AND Table 8 RMON support supplied by the Switch RMON group Alarms Events When using the RMON features of the Switch, note the following: Alarm Events You can define alarms for the Switch. The events that you can define for each alarm and their resulting actions are listed in Table 9 Alarm Events Event... -
Page 63: Setting U P Virtual Lans
Setting up Virtual LANs (VLANs) on your Switch increases the efficiency of your network by dividing the LAN into logical, rather than physical, segments which are easier to manage. This chapter explains more about the concept of VLANs and explains how they can be implemented on your Switch. -
Page 64: Benefits Of Vlans
8: S HAPTER ETTING IRTUAL Figure 16 A network setup showing three VLANs Benefits of VLANs The main benefit of VLANs is that they provide a network segmentation system that is far more flexible than any traditional network. Using VLANs also provides you with three other benefits: Backbone connecting multiple switches Switch A... -
Page 65: Vlans And Your Switch
VLANs and Your Your Switch provides support for VLANs using the IEEE Std 802.1Q-1998. Switch This standard allows traffic from multiple VLANs to be carried across one physical link. The IEEE Std 802.1Q-1998 allows each port on your Switch to be placed The standard requires that you define the following information about each VLAN on your Switch before the Switch can use it to forward traffic: The Default VLAN... -
Page 66: Creating New Vlans
8: S HAPTER ETTING IRTUAL Figure 17 Two VLANs connected via a router 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 Your Switch supports 802.1Q VLAN tagging, a system that allows traffic Untagged... -
Page 67: Vlan Configuration Examples
identify which packets belong in which VLANs. To communicate between VLANs a router must be used. VLAN This section contains examples of VLAN configurations. It describes how Configuration to set up your Switch to support simple untagged and tagged Examples connections. -
Page 68: Using 802.1Q Tagged Connections
8: S HAPTER ETTING IRTUAL To set up the configuration shown in 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 conguration. - Page 69 To set up the configuration shown in 1 Configure the VLANs on Switch 1 Define VLAN 2. VLAN 1 is the default VLAN and already exists. 2 Add endstation ports on Switch 1 to the VLANs Place the endstation ports in the appropriate VLANs as untagged members.
- Page 70 8: S HAPTER ETTING IRTUAL...
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Page 71: Using Automatic Ip Configuration
SING ONFIGURATION This chapter explains more about 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 that accompanies your Switch. -
Page 72: How Your Switch Obtains Ip Information
9: U HAPTER SING UTOMATIC How Your Switch Your Switch has two ways to obtain its IP address information: Obtains IP Information If you select an option for no IP configuration the Switch will not be accessible from a remote management workstation on the LAN. In addition, the Switch will not be able to respond to SNMP requests. -
Page 73: Server Support
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 the following operating systems: Microsoft Windows 2000 Server Microsoft Windows NT4 Server Sun Solaris v2.5.1 If you want DHCP to be the method for automatic configuration, make... - Page 74 9: U IP C HAPTER SING UTOMATIC ONFIGURATION...
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Page 75: Configuration Rules
Configuration Rules Gigabit Ethernet is designed to run over several media: for Gigabit Ethernet The different types of Gigabit Ethernet media and their specifications are detailed in Table 10 Gigabit Ethernet cabling ONFIGURATION Single-mode fiber optic cable, with connections up to 5 km (3.1 miles). -
Page 76: Configuration Rules For Fast Ethernet
A: C PPENDIX ONFIGURATION Configuration Rules The topology rules for 100 Mbps Fast Ethernet are slightly different to for Fast Ethernet those for 10 Mbps Ethernet. and provides examples of how they allow for large-scale Fast Ethernet networks. Figure 20 Fast Ethernet configuration rules The key topology rules are: ULES Figure 20... -
Page 77: Configuration Rules With Full Duplex
Configuration Rules The Switch provides full duplex support for all its ports, including with Full Duplex Expansion Module ports. Full duplex allows packets to be transmitted and received simultaneously and, in effect, doubles the potential throughput of a link. With full duplex, the Ethernet topology rules are the same, but the Fast Ethernet rules are: A total network span of 325 m (1066 ft) is allowed in single-repeater topologies (one hub stack per wiring closet with a fiber link to the... - Page 78 A: C PPENDIX ONFIGURATION ULES...
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Page 79: N Etwork C Onfiguration
ETWORK XAMPLES This chapter contains the following sections: Simple Network Configuration Examples Advanced Network Configuration Examples ONFIGURATION Desktop Switch Example Improving the Resilience of Your Network Enhancing the Performance of Your Network... -
Page 80: Network Configuration Examples
Example can be used for a group of users that require dedicated 10 Mbps 100 Mbps or 1000 Mbps connections to the desktop. Figure 21 Using the Switch 3812 and Switch 3824 in a desktop environment 1000 Mbps XAMPLES Figure 21... -
Page 81: Advanced Network Configuration Examples
Core Switch Advanced Network Configuration Examples shows how you can set up your network to improve its Switch 3824 Stack of four Switch 4200 units Server on Switch 3824 Stack of four Switch 4200 units Server on... -
Page 82: Enhancing The Performance Of Your Network
Flow control will help avoid packet loss during periods of network congestion. A Gigabit Ethernet backbone is set up between the Switch 3824 and each Switch in the workgroups to increase the bandwidth, and therefore the overall network performance. -
Page 83: Ip Addressing
0 and 255. An example IP address is ‘192.168.100.8’. The IP address can be split into two parts: If your network is internal to your organization only, you may use any arbitrary IP address. 3Com suggests you use addresses in the series DDRESSING IP Addresses... -
Page 84: Advanced Overview
C: IP A PPENDIX DDRESSING 192.168.100.X (where X is a number between 1 and 254) with a subnet mask 255.255.255.0. These suggested IP addresses are part of a group of IP addresses that have been set aside specially for use “in house” only. CAUTION: If your network has a connection to the external IP network, you must apply for a registered IP address. - Page 85 referred to as a field or an octet. Decimal notation converts the value of each field into a decimal number, and the fields are separated by dots. Figure 25 Dotted Decimal Notation for IP Addresses 10011110.01100101.00001010.00100000 The decimal value of an octet whose bits are all 1s is 255. Network Portion The location of the boundary between the network part and the host part depends on the class that the central agency assigns to your...
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Page 86: Subnets And Subnet Masks
C: IP A PPENDIX DDRESSING Subnets and Subnet You can divide your IP network into sub-networks also known as subnets. Masks 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. - Page 87 Subnets and Subnet Masks As shown in this example, the 32 bits of an IP address and subnet mask are usually written using an integer shorthand. This notation translates four consecutive 8-bit groups (octets) into four integers that range from 0 through 255.
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Page 88: Default Gateways
C: IP A PPENDIX DDRESSING Table 12 Subnet Mask Notation The subnet mask 255.255.255.255 is reserved as the default broadcast address. Default Gateways A gateway is a device on your network which is used to forward IP packets to a remote destination. An alternative name for a gateway is a Router. -
Page 89: Glossary
LOSSARY 3Com Network The 3Com network management application used to manage 3Com’s Supervisor networking solutions. 10BASE-T The IEEE specification for 10 Mbps Ethernet over Category 3, 4 or 5 twisted pair cable. 100BASE-FX The IEEE specification for 100 Mbps Fast Ethernet over fiber-optic cable. - Page 90 LOSSARY Fast Ethernet is 100 Mbps, and the bandwidth of Gigabit Ethernet is 1000 Mbps. baud The signalling rate of a line, that is, the number of transitions (voltage or frequency changes) made per second. Also known as line speed. bridge A device that interconnects two LANs of a different type to form a single logical network that comprises of two network segments.
- Page 91 endstation A computer, printer or server that is connected to a network. Ethernet A LAN specification developed jointly by Xerox, Intel and Digital Equipment Corporation. Ethernet networks use CSMA/CD to transmit packets at a rate of 10 Mbps over a variety of cables. Ethernet address See MAC address.
- Page 92 LOSSARY HTTP Hypertext Transfer Protocol. This is a set of rules for exchanging files (text, graphic images, sound, video, and other multimedia files) on the World Wide Web. IEEE Institute of Electrical and Electronics Engineers. This American organization was founded in 1963 and sets standards for computers and communications.
- Page 93 determine which if any multicast traffic needs to be forwarded to each of its subnetworks. Intranet An Intranet is an organization wide network using Internet protocols such as web services, TCP/IP, HTTP and HTML. An Intranet is normally used for internal communication and information, and is not accessible to computers on the wider Internet.
- Page 94 LOSSARY MAC address Media Access Control address; also called hardware or physical address. A layer 2 address associated with a particular network device. Most devices that connect to a LAN have a MAC address assigned to them as they are used to identify other devices in a network. MAC addresses are 6 bytes long.
- Page 95 Rapid Spanning Tree An enhanced version of the Spanning Tree Protocol that allows faster Protocol determination of Spanning Tree topology throughout the bridged network. repeater A simple device that regenerates LAN traffic so that the transmission distance of that signal can be extended. Repeaters are used to connect two LANs of the same network type.
- Page 96 LOSSARY 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 A device that interconnects several LANs to form a single logical LAN that comprises of several LAN segments.
- Page 97 Wide Area Network. A communications network that covers a wide area. A WAN can cover a large geographic area, and may contain several LANs within it.
- Page 98 LOSSARY...
- Page 99 NDEX addresses classes 85 IP 83 aggregated links 12, 19 aging time, definition 46 alarm events 62 Alarms (RMON group) 60, 61 automatic IP configuration 72 auto-negotiation 12, 18 Backup 15 bandwidth 17 BPDUs. See Bridge Protocol Data Units Bridge Identifier 37 Bridge Protocol Data Units 37 Broadcast Storm Control 15 cable...
- Page 100 NDEX learned SDB entries 46 MAC (Media Access Control) addresses IP address 84 manual configuration 72 masks subnet 86 Matrix (RMON group) 61 Max Age 39 multicast filtering 27 IGMP 30 multicasts, description 27 network addresses 83 network configuration examples 80, 81 non-aging learned SDB entries 46 obtaining registered IP address 84...
- Page 101 topology rules for Fast Ethernet 76 topology rules with full duplex 77 traffic prioritization 14, 47, 48 advanced 54 basic 52 classification 49 default configurations 58 differentiated services 50, 51 DiffServ Code Point (DSCP) 51 IEEE Std 802.1D, 1998 Edition 50 marking 50 queues 56 re-marking 52...
- Page 102 NDEX...