ccna explorationg 4.0 - chapter 2 static routing

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Chapter 2-Static Routing
CCNA Exploration 4.0
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Objectives
• Define the general role a router plays in networks.
• Describe the directly connected networks, different router
interfaces
• Examine directly connected networks in the routing table
and use the CDP protocol
• Describe static routes with exit interfaces
• Describe summary and default route
• Examine how packets get forwarded when using static
routes
• Identify how to manage and troubleshoot static routes
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Role of the Router
• The router is a special-purpose computer that plays a key role in
the operation of any data network. Routers are primarily
responsible for interconnecting networks by:
– Determining the best path to send packets.
– Forwarding packets toward their destination.
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Introducing the topology
• Topology Lab
– Three 1800 series routers connected via WAN links.
– Each router connected to a LAN represented by a switch and
a PC.
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Cable for LAN/WAN interfaces
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Examining Router Interfaces
• Examining Router Interfaces
– show ip route command – used to view routing table
– show interfaces command – used to show status of an interface
– show ip Interface brief command – used to show a portion of the
interface information
– show running-config command – used to show configuration file in
RAM
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Configuring an Ethernet Interface
• Configuring an Ethernet interface
– By default all serial and Ethernet interfaces are admintrative down.
– To enable an interface use the no shutdown command.
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Configuring an Ethernet Interface
• Verifying Ethernet interface
– Show interfaces for fastEthernet 0/0 – command used to
show status of fast Ethernet port.
– Show ip interface brief.
– Show running-config.
• Ethernet interfaces participate in ARP
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Logging Synchronous Command
• In order to keep the unsolicited output separate from your input,
enter line configuration mode for the consoled port and add the
logging synchronous command.
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Configuring a Serial Interfaces
• Configuring a Serial interface
– Enter interface configuration mode

– Enter in the ip address and subnet mask
– Enter in the clock rate(DCE) and no shut down command
• Example:
– R1(config)#interface serial 0/0
– R1(config-if)#ip address 172.16.2.1 255.255.255.0
– R1(config-if)#clock rate 64000
– R1(config-if)#no shutdown
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Verifying Changes to the Routing Table
• The routing table consists of a list of "known" network addresses
these addresses that are directly connected, configured
statically, and learned dynamically.
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Verifying Changes to the Routing Table
• Observing Routes as They are Added to the Routing Table
– debug ip routing command will let us see any changes that
the router performs when adding or removing routes.
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Devices on Directly Connected Networks
• When a router only has its interfaces configured, and the routing
table contains the directly connected networks but no other
routes, only devices on those directly connected networks are
reachable.
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Devices on Directly Connected Networks
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Cisco Discovery Protocol (CDP)
Network discovery with CDP
• CDP is an information-gathering tool used by network administrators to
get information about directly connected Cisco devices.

• CDP is a proprietary tool that enables you to access a summary of
protocol and address information about Cisco devices that are directly
connected.
• These advertisements contain information such as the types of devices
that are connected, the router interfaces they are connected to, the
interfaces used to make the connections, and the model numbers of
the devices.
• Concept of neighbors
– 2 types of neighbors
 Layer 3 neighbors.
 Layer 2 neighbors.
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Cisco Discovery Protocol (CDP)
CDP Operation
• CDP runs at the Data Link layer connecting the physical media to the
upper-layer protocols (ULPs).
• Cisco network devices, such as routers that support different Network
layer protocols (for example, IP and Novell IPX), can learn about each
other
• CDP provides the following information about each CDP neighbor
device:
– Device identifiers
– Address list
– Port identifier
– Capabilities list
– Platform
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Default Setting
Feature Default Setting
CDP global state Enabled

CDP interface state Enabled
CDP holdtime (packet holdtime in
seconds)
180
CDP timer (packets sent every x seconds) 60
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Using CDP for Network Discovery
• The information gathered by the CDP protocol can be examined
with the show cdp neighbors command.
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Using CDP for Network Discovery
Field Definition
Device ID The name of the neighbor device and either the
MAC address or the serial number of this
device.
Local Intrfce The protocol being used by the connectivity
media.
Holdtme The remaining amount of time (in seconds) the
current device will hold the CDP advertisement
from a sending router before discarding it.
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Using CDP for Network Discovery
Capability
(Capability
Codes)
Capability (type of routing device) of the listed
neighboring device.
The capability types that can be discovered are:
R—Router
T—Transparent bridge

B—Source-routing bridge
S—Switch
H—Host
I— device is using IGMP
r—Repeater
Platform The product number of the device.
Port ID The protocol and port number of the device.
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Using CDP for Network Discovery
To disable CDP on a
specific interface
after it has been
enabled, use the no
CDP enable
command in interface
configuration mode.
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CDP Commands
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CDP Commands
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CDP Commands
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CDP Commands