Bridging/Switching

  • Name and describe two switching methods.
    • Store-and-forward Switching - Provides error-free method of sending data. Copy the entire contents of the frame into the switch buffer and perform CRC. Typically used in high speed LAN to low speed LAN.
    • Cut-Through Switching - Doesn't check for frame errors. Read the first six-byte of destination address and won't copied the frame into buffer before sending out.
    • Fragmentfree Switching - Used modified version of Cut-Through.  Wait for the collision windows, which is 64 bytes long to pass before forwarding.
  • Distinguish between cut-through and store-and-forward LAN switching - cut-through doesn't check for errors therefore it is faster than store-and-forward and the bad part of cut-through method is that if your network has a high error rate, the switches won't know that and will continue to flood the network with bad frame. As that result bad frames can degrade overall performance by wasting bandwidth.
  • Describe the operation of the Spanning Tree Protocol and its benefits - To prevent routing loop in a network. e.g. If a router or hub has more than one path to the same destination, a routing problem could occur. Main function of STP is to provide redundant network path without suffering the effects of loops.
  • Describe the benefits of virtual LANs.
    • Simply moves, adds and changes
    • Reduce administrative cost
    • Better control of broadcasts
    • Tighten network security
    • Microsegment with scalability
    • Relocate server in secure location

OSI Reference Model & Layered Communications

  • Describe data link and network addresses and identify key differences between them - Provides reliable transit of data across a physical link. Concern with physical addressing, network topology, ine discipline, error notification, ordered delivery of frames and flow control.
  • Define and describe the function of the MAC address - Also known as a hardware address, a MAC-layer address, or a physical address. Required by every port or device that connects to a LAN. Other devices in the network use these addresses to locate specific ports in the network and to create a update routing tables and data structures. MAC addresses are 6 bytes long and are controlled by the IEEE.
  • List the key internetworking functions for the OSI Network layer.
    • Path determination - Choose the best path for data to reach the destination host.
    • Addressing - For any internetwork to function properly it must use a consistent network layer addressing scheme.
    • Routed versus routing protocols - Routed protocols can be any protocol suite that has sufficient information to allow movement through an internetwork. Routing Protocols is used to pass information about routing updates between routers.
    • Heterogeneous Routing - Maintain different routing table based on the protocols that are running on the internetwork.
  • Identify at least three reasons why the industry uses a layered model.
    • Clarify the general functions, rather than specifics on how to do it.
    • Makes the complexity of networking into more manageable sublayers.
    • Uses standard interfaces to enable ease of interoperability.
    • Developers can change the features of one layer without changing all the code.
    • Allows specialization which helps industry to progress.
    • Ease troubleshooting.
  • Describe the two parts of network addressing; then identify the parts in specific protocol address examples.
    • Physical Addressing - Unique address that is burned into each NIC card by the manufacturer.
    • Logical Addressing - Uses flat addressing scheme and sometime referred to as virtual addressing. e.g.
      • LAN protocols.
        • Ethernet
        • FastEthernet
        • Token Ring
      • WAN protocols.
        • PPP
        • X.25
        • Frame Relay
  • Define and explain the five conversion steps of data encapsulation.
    • Create the data - A user use an application to create some sort of message that needs to be sent over the network. e.g. email messages, ftp or web.
    • Get ready to transport the data - The session layer sends the data to the Transport layer, where the header is created before the data portion.
    • Add the logical address - The network layer prepares the information for its journey across the internetwork.
    • Add the MAC address - The source and destination physical address are added to the data. The data link also adds a trailer. This combination is known as frame.
    • Send the bits - Once the physical layer receives the frame, the last task is to put the signals on the wire.
  • Describe connection-oriented network service and connectionless network service, and identify their key differences.
    • Connection-oriented - A packet transmission delivery method design to guarantee that data is delivered without error.
    • Connectionless - A packet transmission delivery method design for high speed with no guarantee of data delivery.
  • Identify the parts in specific protocol address examples.
  • Describe the advantages of LAN segmentation. - Minimizes packet collisions by decreasing the number of workstations on the same physical segment. By keeping the traffic local to the network segment, users have more available bandwidth and enjoy better response time.
  • Describe LAN segmentation using bridges. - Breaks up networks into smaller segments to extend the overall length of LAN and better manage data traffics. Bridge work at MAC sublayer of Data Link layer. They create both physical and logical separate network segments to reduce traffic load.
  • Describe LAN segmentation using routers. - Unlike bridge or a switch router filters frames based on logical address. Works at network layer and are use to route packets to destination networks. Like bridge, use tables to make routing decisions, however routers keep information only on how to get to remote networks in their tables, not to the hosts.
  • Describe LAN segmentation using switches. - Uses MAC address in order to ensure that the packet is forwarded to the right outgoing port. Learn MAC address and store them in an internal lookup table. 
  • Describe the benefits of network segmentation with bridges. - Segmenting a logical network into multiple physical pieces, it ensure network reliability, availability and manageability.
  • Describe the benefits of network segmentation with routers.
    • Manageability - Multiple routing protocols give the network manager who's creating an internetwork a lot of flexibility.
    • Increase functionality - Cisco routers provide features addressing the issues of low, error and congestion control, plus fragmentation, reassembly and control over packet lifetime.
    • Multiple active paths - Using protocol, DSAPs, SSAP and path metrics, routers can informed routing decisions, as well as interpret the next layer protocols. Routers can have ore than one active link between devices.
  • Describe the benefits of network segmentation with switches. - Considerably higher port density at a lower cost than standard bridges. User enjoy instant access to the full available bandwidth.

Network Protocols

  • Describe the different classes of IP addresses (and subnetting).
Class Format Leading bit Pattern Decimal range of first byte of network address Maximum network Maximum nodes per network
A Net.Node.Node.Node.Node 0 1-127 127 16,777,214
B Net.Net.Node.Node 10 128-191 16,384 65,534
C Net.Net.Net.Node 110 192-223 2,097,152 254
  • Describe the different classes of IP addresses (and subnetting).
  • Identify the functions of the TCP/IP network-layer protocol. - Responsible for physical connection and for setting the rules as to how the bits will be put on the wire. Layer are broken into 2 categories LAN and WAN.
  • Identify the functions performed by ICMP. - Provides feedback about problems that may be occurring on the network.
  • Configure IP addresses. - Refer to http://www.certifyexpress.com/cisc/ccna2/subnetting-cramnotes.php for detail info.
  • Verify IP addresses.
  • List the required IPX address and encapsulation type.
    • Ethernet_802.3 - Default up to Netware 3.11
    • Ethernet_802.2 - Default since Netware 3.12
    • Ethernet_II - Support both TCP/IP and IPX
    • Ethernet_SNAP - AppleTalk, IPX and TCP/IP

Routing

  • Define flow control and describe the three basic methods used in networking. - Technique for ensuring that a transmitting entity, such as a modem, does not overwhelm a receiving entity with data.
    • Windowing - Each source host has a maximum data limit set that will let it send only that amount before an acknowledgement from the destination is received.
    • Buffering - Stores small bursts of data in a buffer area until the destination host can process them.
    • Multiplexing - Enable data from several layers to be transmitted onto a single physical link.
  • Add the RIP routing protocol to your configuration.
    1. From Global Configuration mode, enable RIP using the command router rip. This command transfers you to the routing protocol configuration mode. Your prompt changes to Router(config-router)#
    2. Specify the network addresses that should be advertised by RIP. Use the command network <network IP address>. The router can any networks that are directly connected to it.
  • Add the IGRP routing protocol to your configuration. - If your router is using RIP, you must first disable RIP. Use the no router rip command. Use router igrp <AS Number> command to enable IGRP.

WAN Protocols

  • Recognize key Frame Relay terms and features. - Upgrade from X.25 to be used where LAPB is no longer utilized. Does not use error correction. Uses SVCs, PVCs, and DLCIs for addressing.
  • List commands to configure Frame Relay LMIs, maps, and subinterfaces.
    • Command string to configure Frame Relay encapsulation - encapsulation frame-relay [ietf]
    • Command string to configure LMI type - frame-relay lmi-type { ansi | cisco | q933a }
    • Command string to configure subinterfaces on the first physical serial interface - interface serial 0.number
  • List commands to monitor Frame Relay operation in the router.
    • show interfaces [type number]
    • show frame-relay pvc
    • show frame-relay map
  • State a relevant use and context for ISDN networking. - Use existing copper wire. Able to deliver 123Kbps of digital data over the same pair of copper wires.
  • Identify ISDN protocols, function groups, reference points, and channels.
    • Protocols
      • E-series protocols deal with ISDN and telephone network.
      • I-series protocols are the concepts, terminology, and definitions.
      • Q-series protocols defines the way ISDN switching and signaling is performed.
    • Reference point - Identifies a section of the ISDN network between devices used for troubleshooting and conceptual purposes.
    • Channels
      • Basic-Rate Interface (BRI) - 128Kbps over 2 channels.
      • Primary Rate Interface (PRI) - 1.472Mbps over 23 channels in North America and 1.920Mbps over 30 channels in Europe.
  • Identify PPP operations to encapsulate WAN data on Cisco routers.
    • Supports level 3 protocols.
    • Binding multiple protocols over the same link
    • Compression and multilinking to increase throughput
    • Two methods of authentication PAP and CHAP
    • Dynamic address assignment
    • Synchronous as well as asynchronous communications

Network Management

1-99 IP standard access list
100-199 IP extended access list
1000-1099 IPX SAP access list
1100-1199 Extended 48-bit MAC address access list
1200-1299 IPX summary address access list
200-299 Protocol type-code access list
300-399 DECnet access list
600-699 Appletalk access list
700-799 48-bit MAC address access list
800-899 IPX standard access list
900-999 IPX extended access list
  • Configure standard access lists to figure IP traffic. - access-list 10 { permit | deny } (source addess)
  • Configure extended access lists to filter IP traffic. - access-list 110 { permit | deny } protocol (source address) (destination address) port
  • Monitor and verify selected access list operations on the router.
    • show access-1
    • show ip access-list
    • show ip intercase e0
    • show running-config

LAN Design

  • Describe full- and half-duplex Ethernet operation.
    • Full Duplex - Capability for simultaneous data transmission between a sending station and a receiving station.
    • Half Duplex - Capability for data transmission in only one direction at at time between a sending station and a receiving station.
  • Describe network congestion problem in Ethernet networks.
    • Collisions - When a collision occurs, it will cause all hosts to stop sending traffic.
    • Broadcasts - When there are too many hosts in a single segment, the amount of broadcast-based traffic will be more than the physical media can handle.
    • Latency - Occurs when a host is prepared to send traffic, but is required to wait for access to the wire or until an incoming frame is received.
  • Describe the features and benefits of Fast Ethernet.
    • Higher performance of 100Mbps
    • Use of existing cabling and network equipment
    • Dual-speed adapters and switches can be used for easy migration from 10Mbps to 100Mbps
    • Fast Ethernet is based on the proven CSMA/CD technology that is well defined
    • Migration is easy
  • Describe the guidelines and distance limitations of Fast Ethernet.
    • 100BaseFX - Ethernet over fiber at 100Mbps using 802.3 specs. 100 meters (328 feet). Half-Duplex: 412 meters (1351 feet) and Full-Duplex: 2000 meters (6561 feet)
    • 100BaseT4 - Using 802.3 specs, 100Mbps over category 3,4, or 5 cabling with standard RJ-45 connector. 100 Mb/s (full-duplex not supported). 100 meters (328 feet).
    • 100BaseTX - Fast Ethernet over category 5 cabling. 100 Mb/s (200 Mb/s in optional full-duplex mode). It's compatible with, and adheres to, 802.3 specs.  100 meters (328 feet).
    • 100BaseX - This refers to either the 100BaseTX or 100BaseFX media. This standard was approved to ensure compatibility between the Ethernet CSMA/CD and ANSI X3T9.5 standard.
    • 100VG AnyLan - IEEE movement into fast Ethernet and Token Ring that appears to be going nowhere fast, mostly because it's not compatible with the 802.3 standards and Cisco doesn't support it.

Cisco Basics, IOS & Network Basics

  • Examine router elements.
    • ROM - Used by router to store the bootstrap startup program, operating system and Power-On Self Test (POST). Can be replace and upgraded.
    • Flash - An erasable, re-programmable ROM that holds the operating system images and microcode. Flash is retained even when the router is turn off.
    • RAM - Provides caching and packet buffering, plus information like routing tables. Used to hold operating system when the router is powered on. It is cleared when the router is reset  or powered off.
    • NVRAM - nonvolatile RAM that stores the router's startup configuration file. Retain information even when the router is rebooted or shut down.
    • Interfaces - Located either on the motherboard or as a separate modules that ease replacement or upgrade.
    • sh ver - shows the current IOS.
  • Manage configuration files from the privilege EXEC mode.
    • Configuration command summary
Configure terminal Configure manually from the console terminal
Configure memory Load configuration information from NVRAM
Copy tftp running config Load configuration information from a network TFTP server.
Copy run startup config Store the current configuration in RAM into NVRAM.
Show running config Display the current configuration in RAM
Copy running config tftp Store the current configuration in RAM on a network TFTP server
Show startup config Display the saved configuration, which is the contents of NVRAM
Erase startup config Erase the contents of NVRAM.
  • Managing contents of NVRAM (Start Configuration)
configure memory Loads configuration information from NVRAM.
erase startup config or clear startup-config” Erases the contents of NVRAM
copy running config startup config Stores the current configuration in RAM into NVRAM
show startup config Display the saved configuration, which is the contents of NVRAM
  • NVRAM to RAM - A current copy of the startup configuration in NVRAM can be copied to RAM using the copy startup-config run command.
  • RAM to NVRAM - A current copy of the running configuration stored in RAM can be copied to NVRAM using the copy running-config start command.
  • TFTP server - A current copy of the configuration currently in RAM can be stored on a TFTP Server using the copy running-config tftp command. You can configure the router by retrieving the configuration file stored on one of your network server by entering the copy tftp running config command.
  • Control router passwords, identification, and banner.
    • Password
      • Router(config)#enable password mypassword
    • Identification
      • Router(config)#hostname myRouter
    • Banner
      • Router(config)#banner motd #
  • Identify the main Cisco IOS software commands for router startup.
Show start up config or show config Display the backup configuration files
Show running config Display the active configuration files
Clear startup config Delete the backup configuration file in NVRAM
Erase startup config Delete the backup configuration file in NVRAM
Reload The reload command will reboot the router through the entire configuration process
Setup The last command is used to enter setup mode from the privileged EXEC prompt
  • Log in to a router in both user and privilege modes.

Router> User Mode Prompt
Router>enable
Password:*******
Router#
Privileged mode prompt

  • Check an initial configuration using the setup command.
    • Router#show startup-config
  • Use the context-sensitive help facility.
    • Router>Clock?
    • Router>?
  • Use the command history and editing features.
<Crtl><A> Move to the beginning of the command line
<Crtl><E> Move to the end of the command line
<Crtl><F> Move forward one character
<Crtl><B> Move back one character
<Crtl><Z> Backs you out of configuration mode
<Crtl><P> Up arrow or last (previous) command line
<Crtl><N> Down arrow or more recent command recall
<Tab> Entry completion
<Esc><B> Move back one word
<Esc><F> Move forward one word
Show history Show command buffer
Terminal history size Set command buffer size
Terminal no editing Disable advanced editing features
Terminal editing Re-enable advanced editing
  • List the commands to load Cisco IOS software from: Flash memory, a TFTP server, or ROM.

Router# configure terminal

Router(config)# boot system flash {ios-filename}

Router(config)# boot system tftp {ios-filename} {tftp-address}

Router(config)# boot system rom

[Ctrl Z]

Router(config)# copy running config startup config

  • Prepare to backup, upgrade, and load a backup Cisco IOS software image.
    • Creating a Software Image Backup

      Router(boot)# copy flash tftp

      IP address of remote host (255.255.255.255]? 192.16.3.2111

      Filename to write on tftp host? C2500

       

    • Upgrading the Image from the Net

      Router(boot)# copy tftp flash

    IP address of remote host (255.255.255.255]? 192.16.3.211

    Filename to write on tftp host? C2500

     

    Cisco 2500 Series Router IOS Upgrade Steps

    Router# enable

    Router# config t

    Router (config)# config-register 0x2101

    Router (config)# CTRL Z

    Router# wr mem

    Router# reload

    Router(boot)> enable {should return with: (boot)router#}

    Router (boot)# copy tftp flash

    {Enter the necessary IP number of the tftp server}

    {Enter the name of the upgrade file}

    y

    y

    y

    Router (boot)# config t

    Router (boot) (config)# config-register 0x2102

    Router (boot)# CTRL Z

    Router (boot)# wr mem

    Router (boot)# reload

    Router #sho ver

  • List problems that each routing type encounters when dealing with topology changes, and describe techniques to reduce the number of these problems.
  • Prepare the initial configuration of your router and enable IP.

Router# setup

 

--- System Configuration Dialog ---

Continue with configuration dialog? [yes/no]: y

At any point you may enter a question mark '?' for help. Use ctrl-c to abort configuration dialog at any prompt. Default settings are in square brackets '[]'.

 

Basic management setup configures only enough connectivity for management of the system, extended setup will ask you to configure each interface on the system

 

Would you like to enter basic management setup? [yes/no]: y

Configuring global parameters:

 

Enter host name [Router]: Chicago

 

The enable secret is a password used to protect access to privileged EXEC and configuration modes. This password, after entered, becomes encrypted in the configuration.

 

Enter enable secret [<Use current secret>]: secret

 

The enable password is used when you do not specify an enable secret password, with some older software versions, and some boot images.

 

Enter enable password [password]: enable

 

The virtual terminal password is used to protect access to the router over a network interface. Enter virtual terminal password: cisco Configure SNMP Network Management? [no]: n

 

Current interface summary

Interface  IP-Address  OK?  Method  Status    Protocol

BRI0  unassigned  YES  unset  administratively down  down

BRI0:1  unassigned  YES  unset  administratively down  down

BRI0:2  unassigned  YES  unset  administratively down  down

Ethernet0  unassigned  YES  unset  administratively down  down

 

 

Enter interface name used to connect to the management network from the above interface summary: Ethernet0

 

Configuring interface Ethernet0:

Configure IP on this interface? [no]: y

IP address for this interface: 192.168.1.1

Subnet mask for this interface [255.255.255.0] : 255.255.255.0

Class C network is 192.168.1.0, 24 subnet bits; mask is /24

 

The following configuration command script was created:

 

hostname Chicago

enable secret 5 $1$/Hw9/

enable password enable

line vty 0 4

password cisco

no snmp-server

!

no ip routing

!

interface BRI0

shutdown

no ip address

!

interface Ethernet0

no shutdown

ip address 192.168.1.1 255.255.255.0

!

end

 

[0] Go to the IOS command prompt without saving this config.

[1] Return back to the setup without saving this config.

[2] Save this configuration to nvram and exit.

 

Enter your selection [2]: 2

Building configuration...

 

00:04:14: %LINK-3-UPDOWN: Interface BRI0:1, changed state to down

00:04:14: %LINK-3-UPDOWN: Interface BRI0:2, changed state to down

00:04:17: %LINK-3-UPDOWN: Interface Ethernet0, changed state to up

Use the enabled mode 'configure' command to modify this configuration.

 

Chicago#

 

}