3Com 3 - Manual

8 A BOUT T HIS G UIDE Conventions Table 1 and Table 2 list conventions that are used throughout this guide. Table 1 Notice Icons Icon Notice Type Description Information note Information that describes important features or instructions Caution Information that alerts you to potential loss of data o...

Related Documentation 9 Related Documentation In addition to this guide, each Switch documentation set includes the following: ■ 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 manageme...

10 A BOUT T HIS G UIDE Please include the following information when contacting us: ■ Document title ■ Document part number (on the title page) ■ Page number (if appropriate) Example: ■ SuperStack 3 Switch Implementation Guide ■ Part number: DUA1730-0BAA0x ■ Page 25 Please note that we can only resp...

1 S WITCH F EATURES O VERVIEW This chapter contains introductory information about the SuperStack ® 3 Switch management software and supported features. It covers the following topics: ■ What is Management Software? ■ Switch Features Explained For detailed descriptions of the web interface operation...

14 C HAPTER 1: S WITCH F EATURES O VERVIEW Automatic IP Configuration By default the Switch tries to configure itself with IP information without requesting user intervention. It uses the following industry standard methods to allocate the Switch IP information: ■ Dynamic Host Configuration Protocol...

Switch Features Explained 15 For details of the auto-negotiation features supported by your Switch, please refer to the Getting Started Guide that accompanies your Switch. Ports operating at 1000 Mbps only support full duplex mode. Duplex Full duplex mode allows packets to be transmitted and receive...

16 C HAPTER 1: S WITCH F EATURES O VERVIEW Spanning Tree Protocol and Rapid Spanning Tree Protocol Spanning Tree Protocol (STP) and Rapid Spanning Tree Protocol (RSTP) are bridge-based systems that makes your network more resilient to link failure and also provides protection from network loops — on...

Switch Features Explained 17 This system is compatible with the relevant sections of the IEEE 802.1D/D17 standard (incorporating IEEE 802.1p). For more information about 802.1D and traffic prioritization, see Chapter 6 “Using Traffic Prioritization” . Quality of Service Traffic prioritization can be...

18 C HAPTER 1: S WITCH F EATURES O VERVIEW VLANs A Virtual LAN (VLAN) is a flexible group of devices that can be located anywhere in a network, but which communicate as if they are on the same physical segment. With VLANs, you can segment your network without being restricted by physical connections...

2 O PTIMIZING B ANDWIDTH 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: ■ In creased bandwidth ■ Quicker connections ■ Faster transfer of ...

20 C HAPTER 2: O PTIMIZING B ANDWIDTH If 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, whic...

Port Features 21 port and react accordingly. In other words, auto-negotiation may “agree” upon a configuration that the cable cannot sustain; smart auto-sensing can detect this and adjust the link accordingly. For example, smart auto-sensing can detect network problems, such as an unacceptably high ...

22 C HAPTER 2: O PTIMIZING B ANDWIDTH Aggregated Links Aggregated links are connections that allow devices to communicate using up to two links in parallel. Aggregated links are supported on the 10/100/1000BASE-T ports only . These parallel links provide two benefits: ■ They can potentially double t...

Aggregated Links 23 ■ If ports of a different speed are aggregated together, the higher speed links carry the traffic. The lower speed links only carry the traffic if the higher speed links fail. ■ The aggregated link does not support security. ■ Member links must retain the same groupings at both e...

24 C HAPTER 2: O PTIMIZING B 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 hardw...

Aggregated Links 25 Aggregated Link Example The example shown in Figure 3 illustrates an 2 Gbps aggregated link between two Switch units. Figure 3 A 2 Gbps aggregated link between two Switch units To set up this configuration: 1 Add the 1000BASE-T ports on the upper unit to the aggregated link. 2 Ad...

3 U SING M ULTICAST F ILTERING 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: ■ What is an IP Multicast? ■ Mul...

28 C HAPTER 3: U SING M ULTICAST F ILTERING 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: ■ Enables the simultaneous delivery of informati...

Multicast Filtering 29 Figure 4 The effect of multicast filtering Multicast Filtering and Your Switch Your Switch provides automatic multicast filtering support using IGMP (Internet Group Management Protocol) Snooping. It also supports IGMP query mode. Snooping Mode Snooping Mode allows your Switch ...

30 C HAPTER 3: U SING M ULTICAST F ILTERING command will configure the Switch 4200 Series to automatically negotiate with compatible devices on VLAN 1 to become the querier. The Switch 4200 Series is compatible with any device that conforms to the IGMP v2 protocol. IGMP Multicast Filtering IGMP is t...

4 U SING R ESILIENCE F EATURES 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...

34 C HAPTER 4: U SING R ESILIENCE F EATURES Rapid Spanning Tree Protocol (RSTP) The Rapid Spanning Tree (RSTP) is an enhanced Spanning Tree feature. RSTP implements the Spanning Tree Algorithm and Protocol, as defined in the IEEE 802.1w standard. 3Com recommends that you use the Rapid Spanning Tree ...

What is STP? 35 Figure 5 A network configuration that creates loops Figure 6 shows the result of enabling STP on the bridges in the configuration. STP detects the duplicate paths and prevents, or blocks , one of them from forwarding traffic, so this configuration will work satisfactorily. STP has de...

36 C HAPTER 4: U SING R ESILIENCE F EATURES Figure 7 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...

How STP Works 37 cost, the less efficient the link. Table 3 shows the default port costs for a Switch. Table 3 Default port costs 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 o...

38 C HAPTER 4: U SING R ESILIENCE F EATURES STP Configuration After all the bridges on the network have agreed on the identity of the Root Bridge, and have established the other relevant parameters, each bridge is configured to forward traffic only between its Root Port and the Designated Bridge Por...

How STP Works 39 Figure 8 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. Port 1 on Bridge A is therefore selected as the...

40 C HAPTER 4: U SING R ESILIENCE F EATURES ■ 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 ...

42 C HAPTER 4: U SING R ESILIENCE F EATURES Default Behavior This section contains important information to note when using the RSTP and Fast Start features, particularly if you already have existing Switch 4200 units in your network with an older version of software. RSTP Default Behavior When usin...

Using STP on a Network with Multiple VLANs 43 Figure 10 Configuration that separates VLANs To avoid any VLAN subdivision, it is recommended that all inter-Switch connections are made members of all available 802.1Q VLANs to ensure connectivity at all times. For example, the connections between Switc...

5 U SING THE S WITCH D ATABASE What is the Switch Database? The Switch Database is used by the Switch to determine where a packet 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: ■ M...

46 C HAPTER 5: U SING THE S WITCH D ATABASE Switch Database Entry States Databases entries can have three states: ■ 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 Da...

6 U SING T RAFFIC P RIORITIZATION Using the traffic prioritization capabilities of your Switch allows your network traffic to be prioritized to ensure that high priority data is transmitted with minimum delay. For a list of the features supported by your Switch, please refer to the Management Quick ...

48 C HAPTER 6: U SING T RAFFIC P RIORITIZATION ■ Resource planning applications — Used by organizations that require predictable and reliable access to enterprise resource planning applications such as SAP. ■ Financial applications — Used by Accounts departments that need immediate access to large f...

How Traffic Prioritization Works 49 You cannot alter the mapping of the priorities. These are fixed to the traffic types as shown in Figure 11 . Figure 11 IEEE 802.1D traffic types Figure 11 illustrates IEEE 802.1D traffic types as well as associated priority levels and how they are mapped to the tw...

50 C HAPTER 6: U SING T RAFFIC P RIORITIZATION Figure 12 DSCP Service Level Mapping Figure 12 illustrates how DiffServ code point (DSCP) service levels are mapped to the two Traffic Queues. The DSCP service level of the packet is not altered by the Switch 4200. Traffic Prioritization and your Switch...

Traffic Prioritization and your Switch 51 How traffic is processed to provide Quality of Service A received packet at the ingress port is checked for its DSCP and IEEE 802.1D attributes to determine the level of service that the packet should receive. 802.1D packets are categorized into the 8 traffi...

52 C HAPTER 6: U SING T RAFFIC P RIORITIZATION somewhere else in the network and not in the Switch 4200. Note also that 802.1D service levels are fixed and cannot be altered. 3 Create Profiles The next step is to create a profile, which associates classifiers with service levels. 4 Apply Qos profile...

7 S TATUS M ONITORING AND S TATISTICS This chapter contains details of the features that assist 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...

54 C HAPTER 7: S TATUS M ONITORING AND S TATISTICS the same network as the Switch and can manage the Switch by in-band or out-of-band connections. The RMON Groups The IETF define groups of Ethernet RMON statistics. This section describes the two groups supported by the Switch 4200 Series, and detail...

RMON and the Switch 55 addition, probes record the behavior of your network, so that you can analyze the causes of problems. ■ It reduces the load on the network and the management workstation Traditional network management involves a management workstation polling network devices at regular interva...

56 C HAPTER 7: S TATUS M ONITORING AND S TATISTICS Alarm Events You can define up to 200 alarms for the Switch. The events that you can define for each alarm and their resulting actions are listed in Table 5. The Default Alarm Settings A new or initialized Switch has the following alarm(s) defined f...

RMON and the Switch 57 The Audit Log The Switch keeps an audit log of all management user sessions, providing a record of a variety of changes, including ones relating to RMON. The log can only be read by users at the security access level using an SNMP Network Management application. Each entry in ...

58 C HAPTER 7: S TATUS M ONITORING AND S TATISTICS You can configure the email address to which you wish the notifications to be sent. However, you cannot change the factory default notification messages for event emails. RMON traps continue to be sent, in addition to any email notifications you may...

Hardware Status Monitoring 59 Figure 13 Example CLI screen text Figure 14 Example of an individual unit system summary screen ■ Via the web. On the Web interface, an indication of a general hardware failure will be provided through the top-level System Summary information screen. You should refer to...

60 C HAPTER 7: S TATUS M ONITORING AND S TATISTICS Figure 15 Example device summary web page ■ RMON Trap See “Events” on page 54 for details of this feature of your Switch. ■ RMON Event Notification. You can configure Event Notification for fan failure; refer to “Email Notification of Events” on pag...

8 S ETTING U P V IRTUAL LAN S Setting up Virtual LANs (VLANs) on your Switch reduces the time and effort required by many network administration tasks, and increases the efficiency of your network. This chapter explains more about the concept of VLANs and explains how they can be implemented on your...

62 C HAPTER 8: S ETTING U P V IRTUAL LAN S 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: ■ V...

VLANs and Your Switch 63 ■ VLANs help to control traffic With traditional networks, congestion can be caused by broadcast traffic that is directed to all network devices whether they require it or not. VLANs increase the efficiency of your network because each VLAN can be set up to contain only thos...

64 C HAPTER 8: S ETTING U P V IRTUAL LAN S VLANs: Tagged and Untagged Membership Your Switch supports 802.1Q VLAN tagging, a system that allows traffic for multiple VLANs to be carried on a single physical (backbone) link. When setting up VLANs you need to understand when to use untagged and tagged ...

VLANs and Your Switch 65 Connecting VLANS to Other VLANS If the devices placed in a VLAN need to communicate to devices in a different LAN, each VLAN requires a connection to a router or Layer 3 switching device. Communication between VLANs can only take place if they are all connected to a routing ...

66 C HAPTER 8: S ETTING U P V IRTUAL LAN S VLAN Configuration Examples This section contains examples of simple VLAN configurations. It describes how to set up your switch to support simple untagged and tagged connections. Using Untagged Connections The simplest VLAN operates in a small network usin...

VLAN Configuration Examples 67 2 Add ports to the VLANs Add ports 10, 11 and 12 of the Switch as untagged members to VLAN 2. Using 802.1Q Tagged Connections In a network where the VLANs are distributed amongst more than one Switch, you must use 802.1Q tagged connections so that all VLAN traffic can ...

9 U SING A UTOMATIC IP C 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...

70 C HAPTER 9: U SING A UTOMATIC IP C ONFIGURATION How Your Switch Obtains IP Information You can use one of the following methods to allocate IP information to your Switch (essential if you wish to manage your Switch across the network): ■ Automatic IP Configuration (default) — the Switch tries to ...

How Automatic IP Configuration Works 71 Automatic Process To detect its IP information using the automatic configuration process, the Switch goes through the following sequence of steps: 1 The DHCP client that resides in the Switch makes up to four attempts to contact a DHCP server on the network re...

72 C HAPTER 9: U SING A UTOMATIC IP C ONFIGURATION Important Considerations This section 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...

II A PPENDICES AND I NDEX Appendix A Configuration Rules Appendix B Network Configuration Examples Appendix C IP Addressing Glossary Index

A C ONFIGURATION R ULES Configuration Rules for Gigabit Ethernet Gigabit Ethernet is designed to run over several media: ■ Single-mode fiber optic cable, with connections up to 5 km (3.1 miles). Support for distances over 5 km is supported depending on the module specification. ■ Multimode fiber opt...

76 A PPENDIX A: C ONFIGURATION R ULES Configuration Rules for Fast Ethernet The topology rules for 100 Mbps Fast Ethernet are slightly different to those for 10 Mbps Ethernet. Figure 20 illustrates the key topology rules and provides examples of how they allow for large-scale Fast Ethernet networks....

Configuration Rules for Fast Ethernet 77 collapsed backbone). For 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 with Full Duplex The Switch provides full duplex support for all it...

B N ETWORK C ONFIGURATION E XAMPLES This chapter contains the following sections: ■ Simple Network Configuration Examples ■ Segmentation Switch Example ■ Collapsed Backbone Switch Example ■ Desktop Switch Example ■ Advanced Network Configuration Examples ■ Improving the Resilience of Your Network ■ ...

80 A PPENDIX B: N ETWORK C ONFIGURATION E XAMPLES Simple Network Configuration Examples The following illustrations show some simple examples of how the Switch 4200 family and 4900 family can be used in your network. Segmentation Switch Example The example in Figure 21 shows how a 10/100 Switch such...

Simple Network Configuration Examples 81 Collapsed Backbone Switch Example The example in Figure 22 shows how a Switch 4200 stack can act as a backbone for both shared and switched network segments. Figure 22 Using the Switch 4200 as a collapsed backbone Switch 4200 stack Endstations onswitched 10 M...

82 A PPENDIX B: N ETWORK C ONFIGURATION E XAMPLES Desktop Switch Example The example in Figure 23 shows how a Switch 4200 can be used for a group of users that require dedicated 10 Mbps or 100 Mbps connections to the desktop. The Switch 4200 stack has a 1000BASE-T Module fitted that allows it to pro...

Advanced Network Configuration Examples 83 Advanced Network Configuration Examples This section shows some network examples that illustrate how you can set up your network for optimum performance using some of the features supported by your Switch. Improving the Resilience of Your Network Figure 24 ...

84 A PPENDIX B: N ETWORK C ONFIGURATION E XAMPLES Enhancing the Performance of Your Network Figure 25 shows how you can set your network up to enhance its performance. All ports are auto-negotiating and smart auto-sensing and will therefore pass data across the network at the optimum available speed...

C IP A DDRESSING 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 w...

86 A PPENDIX C: IP A DDRESSING 192.168.100. X (where X is a number between 1 and 254) with a subnet mask 255.255.255.0. If you are using SLIP, use the default SLIP address of 192.168.101.1 with a subnet mask of 255.255.255.0. These suggested IP addresses are part of a group of IP addresses that have...

IP Addresses 87 Dotted Decimal Notation The actual IP address is a 32-bit number that is stored in binary format. These 32 bits are segmented into 4 groups of 8 bits — each group is referred to as a field or an octet . Decimal notation converts the value of each field into a decimal number, and the ...

88 A PPENDIX C: IP A DDRESSING 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 net...

Subnets and Subnet Masks 89 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. The subnet mask in the example is writt...

90 A PPENDIX C: IP A DDRESSING 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. “Remote” refers to a destina...

G LOSSARY 3Com Network Supervisor The 3Com network management application used to manage 3Com’s 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. ...

92 G 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 . BOOTP The BOOTP protocol allows you to automatically map an IP...

94 G LOSSARY gateway See router . GBIC Gigabit Interface Converter. Gigabit Ethernet IEEE standard 802.3z for 1000 Mbps Ethernet; it is compatible with existing 10/100 Mbps Ethernet standards. half duplex A system that allows packets to transmitted and received, but not at the same time. Contrast wi...

96 G LOSSARY loop An event that occurs when two network devices are connected by more than one path, thereby causing packets to repeatedly cycle around the network and not reach their destination. MAC Media Access Control. A protocol specified by the IEEE for determining which devices have access to...

99 TCP relates to the content of the data travelling through a network — ensuring that the information sent arrives in one piece when it reaches its destination. IP relates to the address of the endstation to which data is being sent, as well as the address of the destination network. Telnet A TCP/I...

I NDEX Numbers 802.1D priority levels 48traffic classification 48 802.1Q tagging 64 A addresses classes 87IP 85 aggregated links 14, 22 example 25 aging time, definition 46alarm events 56alarm settings, default 56Alarms (RMON group) 54, 55audit log 57auto-IP 14, 70automatic IP configuration 14, 70au...