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Origins and Understanding of Frame Relay
 Frame relay has emerged to provide higher throughput, higher
bandwidth, more cost-effective packet-style data transport, and
take advantage of new digital and fiber-optic transmission
facilities.
 Frame relay combines the advantages of both time division and
statistical multiplexing on a single-access circuit, while
maintaining low end-to-end network latency
 Frame relay allows speeds up to T1 (theoretically up to 45 Mbps)
while switching frames of fixed or variable size over PVCs and
SVCs
 Frame relay standards are derived from the ISDN Link Access
Procedure for the D-channel
Frame Relay Defined
 A FR user –access port connects to the FR network-access port
through the use of a FR user access circuit, also called a User-toNetwork Interface (UNI)
 One or multiple Permanent Virtual Circuits (PVCs) reside within a
single UNI.
 Each PVC is bidirectional and each direction has an assigned
Committed Information Rate (CIR).
 Each endpoint of the PVC has an identifier called a Data Link
Connection Identifier (DLCI)
 Refer to Figure 10.1 (p. 364)
FR User-Access Ports and Circuits (FR UNIs)
 The FR user access port is a physical port on the Customer
Premises Equipment (CPE) such as a router
 The FR user-access port is connected to a single FR access
circuit, typically a digital DS0, fractional T1, or a DS1
 This FR access circuit is then connected to a FR networkaccess port, which is the physical port on a FR switch at the
service provider’s premises
 This access circuit is named User-to-Network Interface (UNI)
 Refer to Figure 10.2 (p. 364)
Permanent Virtual Circuit (PVC)
 Each FR UNI supports one or more PVCs
 PVCs are virtual circuits, or virtual private lines, provisioned
point-to-point from one FR user-access port to another FR useraccess port
 While each end of the PVC will terminate on a FR switch port,
the user sees one end-to-end PVC from user port to user port.
 Refer to Figure 10.3a (p. 366)
 The user devices view a PVC from FR user-access port to useraccess port, when in reality they are defined between two FR
access ports
Permanent Virtual Circuit (PVC) (Continue…)
 Any data transmitted over PVC arrives in exact sequence as it
was sent, and end-to-end security of the circuit is the same
 PVCs are switched by FR switches within the FR network
 Refer to Figure 10.3b (p. 366)
 Refer to Figure 10.4 (p. 366)
 PVC does not consume bandwidth when it is not transmitting
data.
 Each FR access circuit can contain up to 1024 PVCs in theory,
but service providers and CPE typically support a maximum of
one hundred
Committed Information Rate (CIR)
 CIR is a quality-of-service measurement that provides a
“statistically guaranteed” minimum rate of throughput to its
PVC at any one period of time
 CIR rates are unidirectional, in that each PVC has a CIR rate
for each direction
 Refer to Figure 10.5 (p. 368)
 CIRs that are able to assign different rates to each direction of
the PVC are called unidirectional or simplex CIRs
Data Link Connection Identifier (DLCI)
 DLCI provides each PVC with a unique identifier at both the
CPE device and the FR switch
Frame Relay Functions – Putting it all together
 Frame relay provides an upgrade to existing packet switching
technology, by supporting speeds up to DS3 (45 Mbps)
 Frame relay supports PVCs for static user configurations and
SVCs for the infrequent user who requires virtual circuits-on
demand.
 Frame relay is a service that delivers frames in order with high
probability and can operate effectively only on low error-rate
media
 Frame relay acts as a data link protocol to higher layer
protocols, such as TCP/IP
Frame Relay Functions – Putting it all together
(Continue…)
 Frame relay virtual circuits (PVCs and SVCs) may be point-topoint or point-to-multipoint (called multicast)
 Frame relay virtual circuits may be arranged into closed user
groups for security purposes
Frame Relay Access to a FR Network
 Frame relay defines both a packet-access technique which
provides bandwidth-on-demand and a data link OSIRM layer 2
interface
 The interface transmits frames to a public or private network
service and on to a destination interface over a PVC.
 The end points of the PVCs are defined by a source and
destination address or Data Link Connection Identifier (DLCI)
 As an interface, Frame relay operates over BRI and PRI ISDN,
V-series, DDS and DDN, fractional T1, X.21, T3, and even
SONET
Frame Relay Access to a FR Network
(Continue…)
 Refer to Figure 10.7 (p. 371)
 The frame relay switch can either be at the LEC PoP, IXC PoP,
or service provider location.
 The local loop is typically DS0, fractional T1, or T1
 Frame Relay Access Device or Assembler/Disassembler
(FRAD) is used to combine mixed subrate protocols which are
aggregated into a single frame relay access circuit and
transmitted to the frame relay network
 Refer to Figure 10.8 (p. 371)
Frame Relay Access to a FR Network
(Continue…)
 Frame relay access provides a cost-effective solution for the
transport of bursty data, such as LAN traffic.
 FR’s statistical multiplexing capability makes it an ideal choice
for aggregation of multiple private lines up to T1 speeds
 Multiple logical circuits can be combined within a single
physical circuit
 Frame relay as a network access offers the following benefits
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Equipment and local loop services
Maximizes link efficiency
True international standard
Equipment and Local Loop Savings
 By allowing multiple users access to a single shared physical
access circuit, tremendous savings in network interface
equipment, local loops, and long distance IXC bandwidth costs
can be achieved
 Refer to Figure 10.11 (p. 374)
 Refer to Figure 10.12 (p. 375)
 Refer to Figure 10.13 (p. 375)
 Refer to Figure 10.14 (p. 376)
Maximizes Link Efficiency
 FR makes maximum use of physical circuit bandwidth by
statistically multiplexing multiple PVCs over a single physical
circuit.
Frame Relay as a Signaling Protocol
 The OSIRM layer 2 is split by frame relay standards into two
major areas: core services and user-defined services
 Benefits of using frame relay are
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In-band CPE management - Transparent to higher layer protocols
In-band link management - Improved performance over packet
switching
Protocol flexibility
- Flexibility of bandwidth allocation
Frame Relay as a Network Service
 Frame relay has become one of the primary LEC and IXC data
service offerings
 Frame relay service does provide the concentration and
statistical multiplexing of X.25 packet switching, while
providing the short delay and high speed switching of TDM
multiplexers
 Permanent Virtual Circuits (PVCs) and Switched Virtual
Circuits (SVCs) are established from one-to-one or many-toone (multicast) end points, with a dynamic route through the
“cloud”
Frame Relay as a Network Service (Continue…)
 A typical frame relay public data transport network will support a variety of
user access devices, including T1/E1 multiplexer, bridge, router, gateway,
front-end processor, an X.25 packet switch, and a Frame Relay Access
Device or Assembler/Disassembler (FRAD)
 Refer to Figure 10.16 (p. 380)
 Frame relay as a network service offers the following benefits:

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Circuit savings
Higher network availability
Latency increases or reductions
Lower WAN costs
- Higher circuit availability
- Prevention from technology discontinuity
– Dynamic circuit and network architecture
- Fills the need for high-speed LAN-toWAN connectivity
One network – multiple protocols - Managed service and guarantee of
availability
Frame Relay Protocol Structure in Relation to the
OSIRM
 Frame relay transport comprises only the first two layers of the
OSI model, the physical and data link layers
 Refer to Figure 10.19 (p. 385)
 The physical layer interface can range from a DS0, through
fractional T1, up to and including a full T1
 Layer 2 utilizes the ITU-T/CCITT link access procedure (LAPD) data link layer protocol
 Frames are transmitted between nodes at the OSI layer 2 data
link layer
Frame Relay Protocol Structure in Relation to the
OSIRM (Continue…)
 Frame relay checks for frame validity with the Frame Check
Sequence (FCS) and frames are discarded if in error
 FR nodes establish permanent virtual circuits and route the data
through this point-to-point serial connection
 Frames are routed by destination addresses (DLCI)
 Refer to Figure 10.20 (p. 386)
 FR switches operate at layer 2, while the transport of data
across the UNI operates at layer 1
 Refer to Figure 10.21 (p. 387)
Layer 2 Protocol Structure Details
 Frame relay service is concerned with two logically separate
levels of the data link layer, defined as the control plane (Cplane) and the user plane (U-plane)
 Refer to Figure 10.22 (p. 388)
 The U-plane provides the data transport of the user data via the
physical access line through logical links
 The control plane is involved with reporting on the status of
PVCs, or the establishments of SVCs
 The C-plane can perform frame relaying by two methods:
Virtual Calls (VCs) and Permanent Virtual Connections (PVCs)
Layer 2 Protocol Structure Details (Continue…)
 The U-plane is split into core functions and user-selectable
terminal functions
 The C-plane is also split into layer 2 and layer 3 services, or the
procedures necessary for signaling
Core Services
 Core services correspond to the U-plane functionality, which
defines user-selectable frame-relaying services
 Refer to Figure 10.25 (p. 391)
Procedural Sublayer Services
 The procedural sublayer defines procedures for data transport
from the user device to the network and between devices.
 This is where true signaling information is managed
Transmission Protocol Theory
Overview
 The high throughput of frame relay is achieved by removing
correction and foregoing addressing overhead functions found
resident in traditional packet-switching technologies
 Frame relay provides fast reconnect and statistical multiplexing
 Highly reliable digital facilities or fiber-optic transmission are
preferred in the frame relay environment because virtual errorfree transmission media is essential
 Frame relay differs from TDM and FDM multiplexer networks
in that the statistical properties of frame relay allocate
bandwidth only as needed
 Refer to Figure 10.26 (p. 393)
 With frame relay access, each user (protocol) is assigned a
virtual channel
 Frame relay networks can be much more efficient compared to
private line networks based on the number of access circuits
 Refer to Figure 10.27 (p. 394)
 Depending on the specific vendor implementation, intermediate
nodes often do not perform any packet disassembly or error
correction
 Refer to Figure 10.28 (p. 396)
Basics of SAP and DLCI
 ITU-T/CCITT Q.920 defines the terms and basic concepts of
DLCI data link addressing.
 The Service Access Point (SAP) is the logical-level data link
interface from the user to the network.
 The SAP provides services to layer 3 protocols. There are
multiple data link connection endpoints associated with each
SAP, and at the link layer, these are referred to as Data Link
Connection Identifiers or DLCIs.
 Refer to Figure 10.29 (p. 397)
Frame Format
 The frame format used by frame relay services is a derivative of
the ISDN Link Access Protocol D-channel (LAP-D) framing
structure
 Refer to Figure 10.31 (p. 398)
 Refer to Figure 10.32 (p. 398)
Address Field Structure
 The Data Link Connection Identifier (DLCI) is split into two
fields, together forming a 10-bit DLCI that identifies up to 1024
virtual circuits per interface
Address Field Structure (Continue…)
 This DLCI identifies the logical channel connection within the
physical channel or port for a predetermined destination
 The DLCI may have local significance on an access circuit or
global significance to the FR network
 Global DLCI assignment is when each user CPE device must
have a separate DLCI for each destination. This limits the size
of a frame relay network to approximately 1000 nodes
 FR service providers use local significant DLCI assignment
where the DLCI is significant to the FR access port only
 DLCI numbers may be used on each FR access circuit across
the network
Address Field Structure (Continue…)
 Almost all North American frame relay implementations use
local significant DLCI assignment method
 The Command/Response (C/R) bit is not used at this time
 The Forward Explicit Congestion Notification (FECN) bit is a
toggle that tells the remote user that network congestion was
encountered by the frame transmitted across the physical media,
and that the user should take action to prevent data loss
 The Backward Explicit Congestion Notification (BECN) bit
works the same, but notifies the sender of congestion in the data
on the returning path
Address Field Structure (Continue…)
 The Discard Eligibility (DE) bit, when set at 1, indicates that
the frame should be discarded during congestion conditions, as
opposed to discarding other frame with a higher priority (those
set at 0)
 The Extended Address (EA) bits act as address field delimiters,
set at 0 and 1, respectively.
 Each user CPE device with multiple logical and physical ports
must have a separate DLCI for each destination on the egress
port it wants to transmit to.
 These DLCIs are built into the switching/routing tables of each
CPE and switching device on the network
Data Field or Payload Structure
 The data field or “payload” structure can vary in size up to
4096 or 8188 octets long.
 The data can be either pure data - when using a direct
connection to a device that provides a frame relay interface - or
it can be encapsulated packets of a different protocol
 Refer to Figure 10.35 (p. 403)
Frame Check Sequence (FCS)
 The FCS field assures the data integrity of the frame. If there is
an error, the frame is discarded.
Frame Relay Addressing
 A Data Link connection Identifier (DLCI) provides each PVC
with an addressing scheme. Each point of a PVC is assigned a
DLCI
 Each frame within a PVC is sent from an originating DLCI to a
destination DLCI where the frame check sequence (FCS) is
verified
 If the frame does not pass the FCS, it is simply discarded with
no indication to the network or user.
 If the frame does pass the FCS, the DLCI is located in a
routing table; routing tables then match addresses, either DLCI
to DLCI, or DLCI to IP
Frame Relay Addressing (Continue…)
 If the DLCI has been predefined for this PVC, the frame will be
routed to its final destination.
 If the DLCI has not been defined for this PVC, it is discarded.
 If it is the destination node, the frame is passed through the
logical and physical port to the user
 Each FR access circuit can contain up to 1024 PVCs. Some of
these are dedicated to LMI, leaving 992 usable DLCIs
 Refer to Figure 10.36 (p. 405)
 Refer to Figure 10.37 (p. 406)
Frame Handling and Switching with ISDN FR Access
 When using an ISDN implementation of frame relay, the Frame
Handlers (FHs) and Remote Frame Handlers (RFHs) perform
much of the frame-relaying service between the physical ports
and the mapping of the logical DLCIs between all ports in a
group.
 Refer to Figure 10.38 (p. 407)
 The frame handler will also





Map in-bound to out-bound DLCI
Perform FCS and correct for retransmission
Discard corrupted frames
Write out-bound DLCI value into the frame-address field
Coordinate transport of frame out of the physical channel
Logical Channel Multiplexing via Frames
 Through the use of the DLCI addressing, multiple user logical
data streams can be multiplexed and demultiplexed within the
same physical data channel
 Each physical channel can contain up to 1023 logical channels,
each identified by a DLCI value
 These multiplexed users are assembled into frames and
transmitted across the network.
 These frames retain their order of transmission and reception.
Each protocol is negotiated during the call establishment
procedure
 Refer to Figure 10.39 (p. 408)
User Interface
 By eliminating the need for multiple access lines by using a
single access into a switched infrastructure, whether a private
or public frame relay network, users can be reduce a significant
portion of networking costs.
 The actual physical user interface is typically an RS-449 or
V.35 connection to a router or switch, although with the drop in
local BRI access charges ISDN interfaces are fast being
deployed.
 With frame relay, the user can minimize the number of
interfaces to the network by using multiple V.35, or four-wire,
if a CSU/DSU is needed
User Applications
 Typical synchronous traffic might include long network connection
times, excessive call setup and takedown times, long transmission
sessions, nonbursty traffic patterns, and PVC connections
 Make sure the applications are well matched to frame relay
Interface Signaling
 Transmission equipment such as CSUs, DSUs, and other
channel-conditioning devices may require in-band or out-ofband signaling.
 This should be transparent to the frame relay transmission,
however, while providing maximum throughput, line efficiency,
and minimum response time degradation and delay
PVC Management
 When a Permanent Virtual Circuit (PVC) is established between
two physical ports and one or multiple DLCI addresses are
established over this link, there is a need for both the network
access device (user) and the network switching device (provider)
to manage the status of the link
 PVC management is defined by ANSI, ITU-T, and the LMI
extensions. These specifications define three main areas of PVC
management:
 PVC status signaling
 DLCI verification
 physical interface keep-alive heartbeat
The Local Management Interface (LMI) Extension
 The LMI extension defines a protocol for managing the frame
relay access circuit from FR CPE to the FR public network
switch.
 The LMI provides a keep-alive signal between the FR CPE and
the FR network access port, makes the initial frame relay circuit
and equipment configuration simpler by allowing notification
of connectivity, and provides a status report for active or
deactivated DLCIs
 Refer to Figure 10.40 (p. 411)
 The LMI extensions define DLCI address number 1023 as the
LMI address
The Local Management Interface (LMI) Extension
(Continue…)
 There are two types of messages:


STATUS_ENQUIRY: is sent by the user device to request a status
message from the network
STATUS: is sent from the network to the user device telling the status of
PVCs in the network connected to that user device
 Information elements can contain a
KEEP_ALIVE_SEQUENCE which proves that both the user
device and the network element are active
 The PVC_STATUS gives the configuration and status of an
existing PVC
The Local Management Interface (LMI) Extension
(Continue…)
 The REPORT_TYPE to indicate either the type of inquiry
requested by the user device or the status message content.
 Refer to Figure 10.42 (p. 413)
Cisco
Managing a Cisco Internetwork
Objectives
 Back up a Cisco IOS to a TFTP server
 Upgrade or restore a Cisco IOS from a TFTP server
 Back up and restore a Cisco router configuration using a
TFTP server
 Use the Cisco Discovery Protocol to gather information
about neighbor devices
 Create a host table on a router and resolve host names to IP
addresses
 Verify your IP host table
 Use the OSI model to test IP
Cisco Router Components
 Bootstrap
 Brings up the router during initialization
 POST
 Checks basic functionality; hardware & interfaces
 ROM monitor
 Manufacturing testing & troubleshooting
 Mini-IOS
 Loads Cisco IOS into flash memory
 RAM
 Holds packet buffers, routing tables, & s/w
 Stores running-config
Cisco Router Components
 ROM
 Starts & maintains the router
 Flash Memory
 Holds Cisco IOS
 Not erased when the router is reloaded
 NVRAM
 Holds router (& switch) configurations
 Not erased when the router is reloaded
 Configuration Register
 Controls how the router boots up
Boot Sequence
#1: Router performs a POST
#2: Bootstrap looks for & loads the Cisco
IOS
#3: IOS software looks for a valid
configuration file
#4: Startup-config file (from NVRAM) is
loaded

If startup-config file is not found, the router
will start the setup mode
Configuration Registers
 Register
 16-bit software written into NVRAM
 Loads from flash memory & looks for the startup-config file
 Configuration Register Bits
 16 bits read 15-0, from left to right
 default setting: 0x2102
Register
Bit number
Binary
2
15 14 13 12
0 0 1 0
1
11 10 9 8
0 0 0 1
0
7 6 5 4
0 0 0 0
2
3 2 1 0
0 0 1 0
NOTE: 0x means the digits that follow are in hexadecimal
Configuration & Boot Field Meanings
Checking the Register Value
Router#sh version
Cisco Internetwork Operating System Software
IOS ™ C2600 Software (C2600-I-M), Version 12.0(3)T3
RELEASE SOFTWARE (fc1)
[output cut]
Configuration register is 0x2102
Changing the Configuration
Register






Force the system into the ROM monitor mode
Select a boot source & default boot filename
Enable or disable the Break function
Set the console terminal baud rate
Load operating software from ROM
Enable booting from a TFTP server
Changing the Configuration
Register
Router(config)#config-register 0x0101
Router(config)#^Z
Router#sh ver
[output cut]
Configuration register is 0x2102 (will be 0x0101 at next reload)
Recovering Passwords
Step #1: Boot the router & interrupt the boot sequence by
performing a break
Step #2: Change the configuration register to turn on bit 6
(0x2142)
Step #3: Reload the router
Step #4: Enter the privileged mode
Step #5: Copy the startup-config to running-config
Step #6: Change the password
Step #7: Reset the configuration register to the default value
Step #8: Reload the router
Recovering Passwords
Step #1: Boot the router & interrupt the boot sequence
by performing a break
Warning: Windows NT’s default HyperTerminal
program will not perform the break
 How to Simulate a Break Key Sequence

Connect to the router with the following terminal settings:

1200 baud rate

No parity
8 data bits
1 stop bit
No flow control




You will no longer be able to see any output on your screen. This is
normal.

Reload the router and press the spacebar for 10-15 seconds. This
generates a signal similar to the break sequence.

Disconnect your terminal and reconnect with a 9600 baud rate. You
should now be in ROM Monitor mode; rommon>
Recovering Passwords
Step #2: Change the configuration register to turn on bit 6
(0x2142)
rommon>confreg 0x2142
You must reset or power cycle for new config to take effect
Step #3: Reload the router

Type reset
 The router will reload & ask if you want to enter setup mode
 Answer NO
Step #4: Enter the privileged mode
Router>enable
Router#
Recovering Passwords
Step #5: Copy the startup-config to running-config
Router#copy startup-config running-config
Step #6: Change the password
Router#config t
Router(config)#enable secret cisco
Step #7: Reset the configuration register to the default
value
Router(config)#config-register 0x2102
Step #8: Reload the router
Backing up & Restoring the Cisco IOS
 Before you upgrade…..

Copy the existing IOS to a TFTP host!
 Verify Flash Memory
Router#sh flash
System flash directory:
File Length Name/status
1 8121000 c2500-js-1.112-18.bin
[8121064 bytes used, 8656152 available, 16777216 total]
16384K bytes of processor board System flash (Read ONLY)
Router#
Backing up the Cisco IOS
#1: Ensure you have good connectivity to
the TFPT host
Router#ping 192.168.0.120
#2: Copy the IOS from flash to the TFTP
host
Router#copy flash tftp

The TFTP host must have a default directory specified
Restoring or Upgrading the Cisco IOS
#1: Ensure you have good connectivity to
the TFTP host
Router#ping 192.168.0.120
#2: Copy the IOS from the TFTP host to
flash
Router#copy tftp flash


The TFTP host must have a default directory specified
Copying the IOS from a TFTP host to flash requires a router reboot
Backing up the Configuration
Step #1: Verify the Current Configuration
Router#sh run
Step #2: Verify the Stored Configuration
Router#sh start
 Verify available memory
Step #3: Copy running-config to NVRAM
Router#copy run start
Router#sh start
Step #4: Copy running-config to a TFTP host
Router#copy run tftp
 A second backup
Restoring the Configuration
 Used when…
 You need to copy the startup-config to the runningconfig


Errors made in editing the running-config
Changes made at the TFTP host need to be copied
to the running-config or startup-config
Router#copy tftp run or Router#copy tftp start

NOTE: The configuration file is ASCII. Any text editor will
enable changes
 Erasing the Configuration
Router#erase startup-config

NOTE: When the router reboots it will be in setup mode
Using Cisco Discovery Protocol
(CDP)
 A Cisco proprietary protocol

Designed to collect information about directly
attached & remote devices
Hardware information
 Protocol information


Useful in troubleshooting & documenting the
network
Getting CDP Timers & Holdtime
Information
 Configuration


CDP Timer: How often CDP packets are transmitted to all
active interfaces
CDP Holdtime: The amount of time that the device will hold
packets received from neighbor devices
Router#sh cdp
Global CDP information
Sending CDP packets every 60 seconds
Sending a holdtime value of 180 seconds
Router#config t
Router(config)#cdp timer 90
Router(config)#cdp holdtime 240
Getting Neighbor Information
 Shows information about directly connected
devices


CDP packets are not passed through a Cisco
switch
Can only see what is directly attached
Router#sh cdp nei
or
Router#sh cdp neighbor detail
 Detailed information; hostname, IP address, etc
Getting Interface Traffic & Port
Information
 Interface Traffic Information:


CDP packets sent & received
Errors with CDP
Router#sh cdp traffic
 Port & Interface Information:


Encapsulation on the line
Timer & Holdtime for each interface
Router#sh cdp interface
Using Telnet
 A virtual terminal protocol


Part of the TCP/IP suite
Allows connections to remote devices
Gather information
 Run programs

NOTE: The VTY passwords must be set on the routers
Using Telnet
 Setting VTY passwords:
Router#config t
Router(config)#line vty 0 4
Router(config)#login
Router(config)#password cisco
Router(config)#^Z
Router#172.16.10.2
Trying 172.16.10.2 … Open
User Access Verification
Password:
RouterB>
Using Telnet
 Setting VTY password:
Router#config t
Router(config)#line vty 0 4
Router(config)#login
Router(config)#password cisco
Router(config)#^Z
Router#172.16.10.2
Trying 172.16.10.2 … Open
User Access Verification
 Remember….


VTY password is the user mode
(>) password - not the enable
mode (#) password
With no enable/enable secret
password set, the following
happens:
RouterB>en
% No password set
RouterB>
This equates to good security!
Password:
RouterB>
Telnet Commands
 Telnetting into Multiple Devices
Ctrl+Shift+6 (release) X
 Checking Telnet Connections
Router#sh sessions
 Checking Telnet Users
Router#sh users
 Closing Telnet Sessions
RouterB>exit
RouterB>disconnect
Resolving Hostnames
 To use a hostname rather than an IP address
to connect to a remote host a device must be
able to translate the hostname to an IP
address


Build a host table on each router
Build a Domain Name System (DNS) server
Building a Host Table
 Provides name resolution only on the router on
which it is built
[ip host name tcp_port_number ip_address]
Router(config)#ip host RouterB 172.16.10.2
Router(config)#ip host switch 192.168.0.148
Router#sh hosts
 Default TCP port number: 23
Router#RouterB
RouterB#(Ctrl+Shift+6) (X)
Router#switch
Using DNS to Resolve Names
 Used when you have many devices on your
network
 Making DNS work…

ip domain-lookup


ip name-server


Turned on by default
Sets the IP address of the DNS server (up to 6 ea.)
ip domain-name

Appends the domain name to the hostname
Ex: RouterA.neversail.navy.mil
Checking Network
Connectivity
 Ping

Displays the minimum, average, & maximum times it
takes for aping packet to find a spedified system + return
Router#ping RouterB
 Trace

Shows the path a packet takes to get to a remote device
Router#trace RouterB
Summary
 Backed up a Cisco IOS to a TFTP server
 Upgraded or restored a Cisco IOS from a TFTP server
 Backed up and restored a Cisco router configuration using a
TFTP server
 Used the Cisco Discovery Protocol to gather information
about neighbor devices
 Created a host table on a router and resolve host names to IP
addresses
 Verified your IP host table
 Used the OSI model to test IP