KTI Networks KGS-2404, KGS-1604 User Manual
KGS-1604
Web Start 16-Port Gigabit Ethernet
Switch
UUsseerr’’ss MMaannuuaal
l
DOC.070710
Web Smart 16-Port Gigabit Ethernet Switch
User's Manual
Release 1.02
Table of Contents
Caution..................................................................................................................................vi
Electronic Emission Notices ................................................................................................. vi
1. Introduction....................................................................................................................... 2
1-1. Overview of 16-Port GbE Web Smart Switch................................................................ 2
1-2. Checklist ........................................................................................................................ 3
1-3. Features ........................................................................................................................ 3
1-4. View of 16-Port GbE Web Smart Switch ....................................................................... 5
1-4-1. User Interfaces on the Front Panel (Button, LEDs and Plugs).............................. 5
1-4-2. User Interfaces on the Rear Panel ........................................................................ 6
1-5. View of the Optional Modules........................................................................................ 7
2. Installation ........................................................................................................................ 8
2-1. Starting 16-Port GbE Web Smart Switch Up ................................................................. 8
2-1-1. Hardware and Cable Installation............................................................................ 8
2-1-2. Cabling Requirements ........................................................................................... 9
2-1-2-1. Cabling Requirements for TP Ports.............................................................. 10
2-1-2-2. Cabling Requirements for 1000SX/LX SFP Module .................................... 10
2-1-2-3. Switch Cascading in Topology.......................................................................11
2-1-3. Configuring the Management Agent of 16-Port GbE Web Smart Switch ............ 14
2-1-4. IP Address Assignment ........................................................................................ 16
2-2. Typical Applications ..................................................................................................... 21
3. Basic Concept and Management ................................................................................... 23
3-1. What’s the Ethernet ..................................................................................................... 23
3-2. Media Access Control (MAC) ...................................................................................... 26
3-3. Flow Control ................................................................................................................ 32
3-4. How does a switch work?............................................................................................ 35
3-5. Virtual LAN................................................................................................................... 39
3-6. Link Aggregation.......................................................................................................... 45
4. Operation of Web-based Management............................................................................. 47
4-1. Web Management Home Overview ............................................................................ 48
4-2. Configuration ............................................................................................................... 50
4-2-1. System Configuration........................................................................................... 51
4-2-2. Ports Configuration .............................................................................................. 54
4-2-3. VLAN Mode Configuration ................................................................................... 56
4-2-4. VLAN Group Configuration .................................................................................. 57
4-2-5. Aggregation .......................................................................................................... 60
4-2-6. LACP.................................................................................................................... 60
4-2-7. RSTP.................................................................................................................... 62
4-2-8. 802.1X.................................................................................................................. 64
4-2-9 IGMP Snooping..................................................................................................... 71
4-2-10. Mirror Configuration ........................................................................................... 73
4-2-11. QoS(Quality of Service) Configuration............................................................... 74
4-2-12 Filter .................................................................................................................... 77
4-2-13 Rate Limit ............................................................................................................ 79
4-2-14 Storm Control...................................................................................................... 80
4-2-15 SNMP.................................................................................................................. 82
4-3. Monitoring .................................................................................................................... 84
4-3-1. Statistics Overview............................................................................................... 84
4-3-2. Detailed Statistics................................................................................................. 85
ii
4-3-3. LACP Status......................................................................................................... 89
4-3-4. RSTP Status......................................................................................................... 90
4-3-5. IGMP Status......................................................................................................... 91
4-3-6. Ping Status........................................................................................................... 92
4-4. Maintenance ................................................................................................................ 94
4-4-1. Warm Restart ....................................................................................................... 95
4-4-2. Factory Default..................................................................................................... 96
4-4-3. Software Upgrade ................................................................................................ 97
4-4-4. Configuration File Transfer................................................................................... 98
4-4-5. Logout .................................................................................................................. 99
5. Maintenance..................................................................................................................... 100
5-1. Resolving No Link Condition ..................................................................................... 100
5-2. Q&A ........................................................................................................................... 100
Appendix A Technical Specifications .................................................................................... 101
Appendix B MIB Specifications ............................................................................................. 105
iii
Revision History
Release Date Revision
1.02 06/28/2007 A2
1.01 03/13/2007 A1
1.00 02/10/2007 A1
iv
v
Caution
Circuit devices are sensitive to static electricity, which can damage their delicate
electronics. Dry weather conditions or walking across a carpeted floor may cause you to
acquire a static electrical charge.
To protect your device, always:
• Touch the metal chassis of your computer to ground the static electrical charge before
you pick up the circuit device.
• Pick up the device by holding it on the left and right edges only.
Electronic Emission Notices
Federal Communications Commission (FCC) Statement
This equipment has been tested and found to comply with the limits for a class A
computing device pursuant to Subpart J of part 15 of FCC Rules, which are designed to
provide reasonable protection against such interference when operated in a commercial
environment.
European Community (CE) Electromagnetic Compatibility Directive
This equipment has been tested and found to comply with the protection requirements
of European Emission Standard EN55022/EN60555-2 and the Generic European Immunity
Standard EN50082-1.
EMC:
EN55022(1988)/CISPR-22(1985) class A
EN60555-2(1995) class A
EN60555-3
IEC1000-4-2(1995) 4K V CD, 8KV, AD
IEC1000-4-3(1995) 3V/m
IEC1000-4-4(1995) 1KV – (power line), 0.5KV – (signal line)
vi
About this user’s manual
This user’s manual provides instructions on how to install your Web Smart Switch.
This guide also covers management options and detailed explanation about
hardware and software functions.
Overview of this user’s manual
Chapter 1 “Introduction” describes the features of 16 Gigabit Web
Smart Switch
Chapter 2 “Installation”
Chapter 3 “Operating Concept and Management”
Chapter 4 “Operation of Web-based Management”
Chapter 5 “Maintenance”
Publication date: June, 2007
Revision A2
1
1. Introduction
1-1. Overview of 16-Port GbE Web Smart Switch
The 16-port Gigabit Web Smart Switch is a standard switch that meets all
IEEE 802.3/u/x/z Gigabit, Fast Ethernet specifications. The switch has 12
10/100/1000Mbps TP ports and 4 Gigabit TP/SFP transceiver slots. It supports
console, telnet, http and SNMP interface for switch management. The network
administrator can logon the switch to monitor, configure and control each port’s
activity. In addition, the switch implements the QoS (Quality of Service), VLAN, and
Trunking. It is suitable for office application.
In this switch, Port 13, 14, 15, 16 includes two types of media --- TP and SFP
Fiber (LC, BiDi…); this port supports 10/100/1000Mbps TP or 1000Mbps SFP Fiber
with auto-detected function. 1000Mbps SFP Fiber transceiver is used for highspeed connection expansion.
1000Mbps LC, Multi-Mode, SFP Fiber transceiver
1000Mbps LC, 10km, SFP Fiber transceiver
1000Mbps LC, 30km, SFP Fiber transceiver
1000Mbps LC, 50km, SFP Fiber transceiver
1000Mbps BiDi, 20km, 1550nm SFP Fiber WDM transceiver
1000Mbps BiDi, 20km, 1310nm SFP Fiber WDM transceiver
10/100/1000Mbps TP is a standard Ethernet port that meets all IEEE
802.3/u/x/z Gigabit, Fast Ethernet specifications. 1000Mbps SFP Fiber transceiver
is a Gigabit Ethernet port that fully complies with all IEEE 802.3z and 1000BaseSX/LX standards.
1000Mbps Single Fiber WDM (BiDi) transceiver is designed with an optic
Wavelength Division Multiplexing (WDM) technology that transports bi-directional
full duplex signal over a single fiber simultaneously.
Key Features in the Device
QoS:
The
switch offers powerful QoS function. This function supports 802.1p
VLAN tag priority and DSCP on Layer 3 of network framework.
VLAN:
Supports Port-based VLAN, IEEE802.1Q Tag VLAN. And supports 24 active
VLANs and VLAN ID 1~4094.
Port Trunking:
Allows one or more links to be aggregated together to form a Link
Aggregation Group by the static setting.
2
1-2. Checklist
Before you start installing the switch, verify that the package contains the
following:
A 12-Port GbE Web Smart Switch
Modules (optional)
Mounting Accessory (for 19” Rack Shelf)
This User's Manual in CD-ROM
AC Power Cord
Please notify your sales representative immediately if any of the aforementioned
items is missing or damaged.
1-3. Features
The 16-Port GbE Web Smart Switch, a standalone off-the-shelf switch,
provides the comprehensive features listed below for users to perform system
network administration and efficiently and securely serve your network.
Hardware
12 10/100/1000Mbps Auto-negotiation Gigabit Ethernet TP ports
4 10/100/1000Mbps TP or 1000Mbps SFP Fiber dual media auto sense
400KB on-chip frame buffer
Jumbo frame support
Programmable classifier for QoS (Layer 2/Layer 3)
8K MAC address and support VLAN ID (1~4094)
Per-port shaping, policing, and Broadcast Storm Control
IEEE802.1Q-in-Q nested VLAN support
Full-duplex flow control (IEEE802.3x) and half-duplex backpressure
Extensive front-panel diagnostic LEDs; System: Power, TP Port1-12: LINK/ACT,
10/100/1000Mbps, SFP Port 13, 14, 15, 16: SFP(LINK/ACT)
Management
Supports concisely the status of port and easily port configuration
Supports per port traffic monitoring counters
Supports a snapshot of the system Information when you login
Supports port mirror function
Supports the static trunk function
2
3
Supports 802.1Q VLAN
Supports user management and limits one user to login
Maximal packet length can be up to 9600 bytes for jumbo frame application
Supports Broadcasting Suppression to avoid network suspended or crashed
Supports to send the trap event while monitored events happened
Supports default configuration which can be restored to overwrite the current
configuration which is working on via Web UI and Reset button of the switch
Supports on-line plug/unplug SFP modules
Supports Quality of Service (QoS) for real time applications based on the
information taken from Layer 2 to Layer 3.
Built-in web-based management instead of using CLI interface, providing a more
convenient GUI for the user
4
1-4. View of 16-Port GbE Web Smart Switch
Fig. 1-1 Full View of 16-PORT GbE Web Smart Switch
1-4-1. User Interfaces on the Front Panel ( Butt on, LEDs and Plugs)
There are 12 TP Gigabit Ethernet ports and 4 SFP fiber ports for optional
removable modules on the front panel of the switch. LED display area, locating on
the left side of the panel, contains a Power LED, which indicates the power status
and 16 ports working status of the switch.
TP Port Status Indication LEDs
Gigabit Ethernet Port
SFP Fiber Port
Power Indication LED
Fiber Port Status Indication LEDs
Fig. 1-2 Front View of 16-Port GbE Web Smart Switch
RESET Button:
RESET button is used to
restore the system default
setting.
2
5
A
LED Indicators
LED Color Function
System LED
POWER Green
10/100/1000Ethernet TP Port 1 to 12 LED
LINK/ACT Green
10/100/1000Mbps
1000SX/LX Gigabit Fiber Port 13, 14, 15, 16 LED
SFP(LINK/ACT) Green
Green/
Amber
1-4-2. User Interfaces on the Rear Panel
Lit when +3.3V power is coming up
Lit when connection with remote device is good
Blinks when any traffic is present
Lit Green when TP link on 1000Mbps speed
Lit Amber when TP link on 100Mbps speed
Off when 10Mbps or no link occur
Blinks when any traffic is present
Lit when SFP connection with remote device is
good
Blinks when any traffic is present
Table1-1
C Line 100-240V 50/60 Hz
Fig. 1-3 Rear View of 16-Port GbE Web Smart Switch
6
1-5. View of the Optional Modules
In the switch, Port 13~16 includes two types of media --- TP and SFP Fiber
(LC, BiDi…); this port supports 10/100/1000Mbps TP or 1000Mbps SFP Fiber with
auto-detected function. 1000Mbps SFP Fiber transceiver is used for high-speed
connection expansion; nine optional SFP types provided for the switch are listed
below:
1000Mbps LC, MM, SFP Fiber transceiver
1000Mbps LC, SM 10km, SFP Fiber transceiver
1000Mbps LC, SM 30km, SFP Fiber transceiver
1000Mbps LC, SM 50km, SFP Fiber transceiver
1000Mbps LC, SM 70km, SFP Fiber transceiver
1000Mbps LC, SM 110km, SFP Fiber transceiver
1000Mbps BiDi, TX=1310nm, SM 20km, SFP Fiber WDM transceiver
1000Mbps BiDi, TX=1550nm, SM 20km, SFP Fiber WDM transceiver
1000Mbps LC, SM 10km, SFP Fiber transceiver with DDM
Fig. 1-4 Front View of 1000Base-SX/LX LC, SFP Fiber Transceiver
Fig. 1-5 Front View of 1000Base-LX BiDi SFP Fiber Transceiver
2
7
r
2. Installation
2-1. Starting 16-Port GbE Web Smart Switch Up
This section describes how to install the Web Smart Switch and its components,
and also includes the following information:
- Hardware and Cable Installation
- Management Station Installation
- Software booting and configuration
2-1-1. Hardware and Cable Installation
At the beginning, please do first:
⇒ Wear a grounding device to avoid the damage from electrostatic discharge
⇒ Be sure that power switch is OFF before you insert the power cord to power
source
Installing Optional SFP Fiber Transceivers to the 16-Port GbE Web Smart
Switch
Note: If you have no modules, please skip this section.
Connecting the SFP Module to the Chassis:
The optional SFP modules are hot swappable, so you can plug or unplug it
before or after powering on.
1. Verify that the SFP module is the right model and conforms to the chassis
2. Slide the module along the slot. Also be sure that the module is properly
seated against the slot socket/connector
3. Install the media cable for network connection
4. Repeat the above steps, as needed, for each module to be installed into
slot(s)
5. Have the power ON after the above procedures are done
Fig. 2-1 Installation of Optional SFP Fiber Transceive
8
TP Port and Cable Installation
⇒ In the switch, TP port supports MDI/MDI-X auto-crossover, so both types of
cable, straight-through (Cable pin-outs for RJ-45 jack 1, 2, 3, 6 to 1, 2, 3, 6 in
10/100M TP; 1, 2, 3, 4, 5, 6, 7, 8 to 1, 2, 3, 4, 5, 6, 7, 8 in Gigabit TP) and
crossed-over (Cable pin-outs for RJ-45 jack 1, 2, 3, 6 to 3, 6, 1, 2) can be used.
It means you do not have to tell from them, just plug it.
⇒ Use Cat. 5 grade RJ-45 TP cable to connect to a TP port of the switch and the
other end is connected to a network-aware device such as a workstation or a
server.
⇒ Repeat the above steps, as needed, for each RJ-45 port to be connected to a
Gigabit 10/100/1000 TP device.
Now, you can start having the switch in operation.
Power On
The switch supports 100-240 VAC, 50-60 Hz power supply. The power
supply will automatically convert the local AC power source to DC power. It does not
matter whether any connection plugged into the switch or not when power on, even
modules as well. After the power is on, all LED indicators will light up and then all off
except the power LED still keeps on. This represents a reset of the system.
Firmware Loading
After resetting, the bootloader will load the firmware into the memory. It will
take about 30 seconds, after that, the switch will flash all the LED once and
automatically performs self-test and is in ready state.
2-1-2. Cabling Requirements
To help ensure a successful installation and keep the network performance
good, please take a care on the cabling requirement. Cables with worse
specification will render the LAN to work poorly.
2
9
2-1-2-1. Cabling Requirements for TP Ports
⇒ For Fast Ethernet TP network connection
The grade of the cable must be Cat. 5 or Cat. 5e with a maximum length of
100 meters.
⇒ Gigabit Ethernet TP network connection
The grade of the cable must be Cat. 5 or Cat. 5e with a maximum length of
100 meters. Cat. 5e is recommended.
2-1-2-2. Cabling Requirements for 1000SX/LX SFP Module
It is more complex and comprehensive contrast to TP cabling in the fiber
media. Basically, there are two categories of fiber, multi mode (MM) and single
mode (SM). The later is categorized into several classes by the distance it supports.
They are SX, LX, LHX, XD, and ZX. From the viewpoint of connector type, there
mainly are LC and BIDI.
Gigabit Fiber with multi-mode LC SFP module
Gigabit Fiber with single-mode LC SFP module
Gigabit Fiber with BiDi 1310nm SFP module
Gigabit Fiber with BiDi 1550nm SFP module
The following table lists the types of fiber that we support and those else not
listed here are available upon request.
Multi-mode Fiber Cable and Modal Bandwidth
IEEE 802.3z
Gigabit Ethernet
1000SX 850nm
1000BaseLX/LHX/XD/ZX
1000Base-LX
Single Fiber
(BIDI)
Table2-1
Multi-mode 62.5/125µm Multi-mode 50/125µm
Modal
Bandwidth
160MHz-Km 220m 400MHz-Km 500m
200MHz-Km 275m 500MHz-Km 550m
Single-mode Fiber 9/125µm
Single-mode transceiver 1310nm 10Km
Single-mode transceiver 1550nm 30, 50Km
Single-Mode
Single-Mode
Distance
*20Km
*20Km
Modal
Bandwidth
TX(Transmit) 1310nm
RX(Receive) 1550nm
TX(Transmit) 1550nm
RX(Receive) 1310nm
Distance
10
2-1-2-3. Switch Cascading in Topology
Takes the Delay Time into Account
Theoretically, the switch partitions the collision domain for each port in switch
cascading that you may up-link the switches unlimitedly. In practice, the network
extension (cascading levels & overall diameter) must follow the constraint of the
IEEE 802.3/802.3u/802.3z and other 802.1 series protocol specifications, in which
the limitations are the timing requirement from physical signals defined by 802.3
series specification of Media Access Control (MAC) and PHY, and timer from some
OSI layer 2 protocols such as 802.1d, 802.1q, LACP and so on.
The fiber, TP cables and devices’ bit-time delay (round trip) are as follows:
1000Base-X TP, Fiber 100Base-TX TP 100Base-FX Fiber
Round trip Delay: 4096 Round trip Delay: 512
Cat. 5 TP Wire: 11.12/m Cat. 5 TP Wire: 1.12/m Fiber Cable: 1.0/m
Fiber Cable : 10.10/m TP to fiber Converter: 56
Bit Time unit : 1ns (1sec./1000 Mega bit)
Bit Time unit: 0.01µs (1sec./100 Mega bit)
Table 2-2
Sum up all elements’ bit-time delay and the overall bit-time delay of
wires/devices must be within Round Trip Delay (bit times) in a half-duplex network
segment (collision domain). For full-duplex operation, this will not be applied. You
may use the TP-Fiber module to extend the TP node distance over fiber optic and
provide the long haul connection.
Typical Network Topology in Deployment
A hierarchical network with minimum levels of switch may reduce the timing
delay between server and client station. Basically, with this approach, it will
minimize the number of switches in any one path; will lower the possibility of
network loop and will improve network efficiency. If more than two switches are
connected in the same network, select one switch as Level 1 switch and connect all
other switches to it at Level 2. Server/Host is recommended to connect to the Level
1 switch. This is general if no VLAN or other special requirements are applied.
11
2
Case1: All switch ports are in the same local area network. Every port can access
each other (See Fig. 2-2).
If VLAN is enabled and configured, each node in the network that can
communicate each other directly is bounded in the same VLAN area.
Here VLAN area is defined by what VLAN you are using. The switch
supports both port-based VLAN and tag-based VLAN. They are different in practical
deployment, especially in physical location. The following diagram shows how it
works and what the difference they are.
Case2a: Port-based VLAN (See Fig.2-3).
Fig. 2-2 No VLAN Configuration Diagram
1. The same VLAN members could not be in different switches.
2. Every VLAN members could not access VLAN members each other.
3. The switch manager has to assign different names for each VLAN groups
at one switch.
Fig. 2-3 Port-based VLAN Diagram
12
Case 2b: Port-based VLAN (See Fig.2-4).
Fig. 2-4 Port-based VLAN Diagram
1. VLAN1 members could not access VLAN2, VLAN3 and VLAN4 members.
2. VLAN2 members could not access VLAN1 and VLAN3 members, but they could
access VLAN4 members.
3. VLAN3 members could not access VLAN1, VLAN2 and VLAN4.
4. VLAN4 members could not access VLAN1 and VLAN3 members, but they could
access VLAN2 members.
Case3a: The same VLAN members can be at different switches with the same VID
(See Fig. 2-5).
Fig. 2-5 Attribute-based VLAN Diagram
2
13
2-1-3. Configuring the Management Agent of 16-Port GbE Web Smart
Switch
In the way of web, user is allowed to startup the switch management function.
Users can use any one of them to monitor and configure the switch. You can touch
them through the following procedures.
Section 2-1-3-1: Configuring Management Agent of 16-Port GbE Web Smart Switch
through Ethernet Port
14
2-1-3-1. Management through Ethernet Port
There are two ways to configure and monitor the switch through the switch’s
Ethernet port. They are Web browser and SNMP manager. We just introduce the
first type of management interface. Web-based UI for the switch is an interface in a
highly friendly way.
16-PORT GBE WEB SMART SWITCH
Default IP Setting:
IP = 192.168.1.1
Subnet Mask = 255.255.255.0
Default Gateway = 192.168.1.254
Ethernet LAN
Assign a reasonable IP address,
For example:
IP = 192.168.1.100
Subnet Mask = 255.255.255.0
Default Gateway = 192.168.1.254
Fig. 2-6
Managing 16-Port GbE Web Smart Switch through Ethernet Port
Before start using the switch, the IP address setting of the switch should be
done, then perform the following steps:
1. Set up a physical path between the configured the switch and a PC
by a qualified UTP Cat. 5 cable with RJ-45 connector.
Note: If PC directly connects to the switch, you have to setup the
same subnet mask between them. But, subnet mask may be
different for the PC in the remote site. Please refer to Fig. 2-6 about
the 16-Port GbE Web Smart Switch default IP address information.
2. Run web browser and follow the menu. Please refer to Chapter 4.
15
2
Fig. 2-7 the Login Screen for Web
2-1-4. IP Address Assignment
For IP address configuration, there are three parameters needed to be filled
in. They are IP address, Subnet Mask, Default Gateway and DNS.
IP address:
The address of the network device in the network is used for internetworking
communication. Its address structure looks is shown in the Fig. 2-8. It is “classful”
because it is split into predefined address classes or categories.
Each class has its own network range between the network identifier and
host identifier in the 32 bits address. Each IP address comprises two parts: network
identifier (address) and host identifier (address). The former indicates the network
where the addressed host resides, and the latter indicates the individual host in the
network which the address of host refers to. And the host identifier must be unique
in the same LAN. Here the term of IP address we used is version 4, known as IPv4.
Network identifier Host identifier
Fig. 2-8 IP address structure
32 bits
16
N
With the classful addressing, it divides IP address into three classes, class A,
class B and class C. The rest of IP addresses are for multicast and broadcast. The
bit length of the network prefix is the same as that of the subnet mask and is
denoted as IP address/X, for example, 192.168.1.0/24. Each class has its address
range described below.
Class A:
Address is less than 126.255.255.255. There are a total of 126 networks can
be defined because the address 0.0.0.0 is reserved for default route and
127.0.0.0/8 is reserved for loopback function.
Bit # 0 1 7 8 31
0
etwork address Host address
Class B:
IP address range between 128.0.0.0 and 191.255.255.255. Each class B
network has a 16-bit network prefix followed 16-bit host address. There are 16,384
(2^14)/16 networks able to be defined with a maximum of 65534 (2^16 –2) hosts
per network.
Bit # 01 2 15 16 31
10
Network address Host address
Class C:
IP address range between 192.0.0.0 and 223.255.255.255. Each class C
network has a 24-bit network prefix followed 8-bit host address. There are
2,097,152 (2^21)/24 networks able to be defined with a maximum of 254 (2^8 –2)
hosts per network.
Bit # 0 1 2 3 23 24 31
110
Network address Host address
2
17
t
N
k
Class D and E:
Class D is a class with first 4 MSB (Most significance bit) set to 1-1-1-0 and
is used for IP Multicast. See also RFC 1112. Class E is a class with first 4 MSB set
to 1-1-1-1 and is used for IP broadcast.
According to IANA (Internet Assigned Numbers Authority), there are three
specific IP address blocks reserved and able to be used for extending internal
network. We call it Private IP address and list below:
Class A 10.0.0.0 --- 10.255.255.255
Class B 172.16.0.0 --- 172.31.255.255
Class C 192.168.0.0 --- 192.168.255.255
Please refer to RFC 1597 and RFC 1466 for more information.
Subnet mask:
It means the sub-division of a class-based network or a CIDR block. The
subnet is used to determine how to split an IP address to the network prefix and the
host address in bitwise basis. It is designed to utilize IP address more efficiently and
ease to manage IP network.
For a class B network, 128.1.2.3, it may have a subnet mask 255.255.0.0 in
default, in which the first two bytes is with all 1s. This means more than 60
thousands of nodes in flat IP address will be at the same network. It’s too large to
manage practically. Now if we divide it into smaller network by extending network
prefix from 16 bits to, say 24 bits, that’s using its third byte to subnet this class B
network. Now it has a subnet mask 255.255.255.0, in which each bit of the first
three bytes is 1. It’s now clear that the first two bytes is used to identify the class B
network, the third byte is used to identify the subnet within this class B network and,
of course, the last byte is the host number.
Not all IP address is available in the sub-netted network. Two special
addresses are reserved. They are the addresses with all zero’s and all one’s host
number. For example, an IP address 128.1.2.128, what IP address reserved will be
looked like? All 0s mean the network itself, and all 1s mean IP broadcast.
10000000.00000001.00000010.1 0000000
etwor
25 bits
All 0s = 128.1.2.128
All 1s= 128.1.2.255
18
Subne
1 0000000
1 1111111
In this diagram, you can see the subnet mask with 25-bit long,
255.255.255.128, contains 126 members in the sub-netted network. Another is that
the length of network prefix equals the number of the bit with 1s in that subnet mask.
With this, you can easily count the number of IP addresses matched. The following
table shows the result.
Prefix Length No. of IP matched No. of Addressable IP
1 2 4 2
8 6
16 14
32 30
64 62
128 126
256 254
512 510
1024 1022
2048 2046
4096 4094
8192 8190
16384 16382
32768 32766
65536 65534
Table 2-3
According to the scheme above, a subnet mask 255.255.255.0 will partition a
network with the class C. It means there will have a maximum of 254 effective
nodes existed in this sub-netted network and is considered a physical network in an
autonomous network. So it owns a network IP address which may looks like
168.1.2.0.
With the subnet mask, a bigger network can be cut into small pieces of
network. If we want to have more than two independent networks in a worknet, a
partition to the network must be performed. In this case, subnet mask must be
applied.
2
19
For different network applications, the subnet mask may look like
255.255.255.240. This means it is a small network accommodating a maximum of
15 nodes in the network.
Default gateway:
For the routed packet, if the destination is not in the routing table, all the
traffic is put into the device with the designated IP address, known as default router.
Basically, it is a routing policy.
For assigning an IP address to the switch, you just have to check what the IP
address of the network will be connected with the switch. Use the same network
address and append your host address to it.
Fig. 2-9
First, IP Address: as shown in the Fig. 2-9, enter “192.168.1.1”, for instance.
For sure, an IP address such as 192.168.1.x must be set on your PC.
Second, Subnet Mask: as shown in the Fig. 2-9, enter “255.255.255.0”. Any
subnet mask such as 255.255.255.x is allowable in this case.
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