Transcript A Router`s Functions - Faculty

Module 6
Routing and Routing Protocols
Routing…
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Nothing more than directions for getting
from one network to another.
_________________________, for traffic
going through a network cloud, occurs at
the network layer
A router makes decisions based upon the
________________________________
__________________________________
_________________________________
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routers must learn the direction to remote
networks by either static or dynamic routing
Dynamic v. Static Routing
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_______________________________
_______________________________
_______________________________.
Static routing is most often used with
stub networks where only one path
exists to the destination.
• _______________
________________
________________
•Allows for
increased security
Static route configuration
using outgoing interface
Going to…
Mask of destination
network
Interface on Hoboken
router closet to destination
network
Static route configuration
using next-hop IP address
Going to…
Mask of destination
network
Serial IP address on
ADJACENT router closet to
destination network
Difference in Configurations
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_______________ assigned to the route by the
router (Hoboken) or network administrator as it is
placed in the routing table.
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Admin. Distance- _____________________
____________________________________________
• Used as a means to find the best path
• ____________________________________________
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Outgoing interface option
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Admin distance = 0
Next-hop IP address
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Admin distance = 1
Static route cont…
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Customize the _________________
_______________ by adding it to
the end of the “ip route” command
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waycross(config)#ip route 172.16.3.0
255.255.255.0 172.16.4.1 _______
If the router cannot reach the
outgoing interface programmed
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____________________________
______________________________
Default Routes
A _____________________________
_______________ that all routers on a
network can send packets to if they __
_______________________________
_____________________________
• The default route concept
assumes that data
forwarded along the default
route will eventually
encounter a router that
DOES know the path to the
destination.
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Default route forwarding
Special static route
 Command
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Issued in global config mode
 ip route _____________________
[next-hop-address | outgoing
interface]
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Verification and troubleshooting
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“_________________________”
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“__________________________”
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used to verify that the static route has
been entered correctly
Used to verify that the route that was
configured is in the _______________
What troubleshooting techniques
can we use to verify connectivity via
a static route?
Dynamic v. Static Routing
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Dynamic routing refers to the process of
_________________________________
____________________________.
Routing protocols enable dynamic routing
where multiple paths to the same
destination exist.
Routed v. Routing Protocols
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Routed (or Routable) protocols are
protocols that ________________
_____________________________
_____________________ using a
hierarchical addressing scheme.
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Carry packaged data
Operate at the ________________
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Examples include ________________
______________________________
Routed v. Routing Protocols
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A routing protocol ____________
_______________________________
___________________________.
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Routers use routing protocols to _______
______________________. These maps
allow ___________________________
____________________. Maps become
part of the router’s routing table.
Allow routers to make decisions
Examples of routing protocols include:
_______________________________
Autonomous System (AS)
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Collection of networks _______________
_________________________ strategy.
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AS is viewed as a single entity
________________________ must be used
between Autonomous systems
Identified by a 16 bit number that _________
_________________ or can be assigned by
the network administrator
Some routing protocols required the use of an
AS
More on routing protocols
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Goal of a routing protocol is to ____
____________________________.
Contains the learned networks and
associated ports for those networks
 ______________________________
_____________________________
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_____________________________
__________________________
Example of a routing
table
This is the interface
number, there could
be any number of
hosts on network
1.0
Routing table used for path determination and packet switching
More on Dynamic routing
Offers _______________________
 Dynamic routing depends on :
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_______________________________
________________________
 ____________________________, to
other routers
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Routing protocols dictate how
communication with neighbors takes
place
Dynamic routing details
cont…
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The best path to a destination, is
determined by _______________
____________________ called…
A _______________________
 _______________________________
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• The fewer the stop signs- the better
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Metrics calculated based on different
__________________________
Characteristics used to generate
the Metric
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___________ - the data capacity of a link;
delay
____________ - the amount of activity on a
network resource such as a router or link
reliability
_______________ - the number of routers a
packet must travel through before reaching
its destination
ticks
________________ - an arbitrary value
assigned by a network administrator
In this example, the metric is comprised of four
different characteristics.
Convergence
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At the time of convergence __________
_________________________________
______________________________
Every time there is a topology change,
routing protocols _________________
_________________________________
_______________________________
The time of convergence varies
depending upon the routing protocol
being used.
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The _______________________________
Distance-vector Routing
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Determines the route based on the direction
(vector) and distance to the destination
Each router receives _____________
___________________________________
__________________________________
Distance-vector protocols _____________
___________________________________
__________________________________
Topology change updates proceed step-bystep from router to router as in the
discovery process
Distance Vector example
___________ seen in Distance
Vector routing protocols
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____________________________
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Can cause Routing Loops
• Occurs when new updated information causes
inconsistent routing entries.
Router X
Internet
Cloud
Link-state (SPF) Routing
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AKA “shortest path first” algorithm
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__________________________________
_________________________________
Link-state protocols maintain complex
__________________________________
________________________________.
Each time a new route is added or a route
goes down, each router receives a
message and then recalculates a spanning
tree algorithm and updates its topology
database.
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Link-state cont…
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Link-state routing algorithm _______________
____________________________________
Link-state advertisements (_________)
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_____________________________________
___________________________________.
_________________________________
_________________________________
______________________
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The router that first becomes aware of a
topology change forwards the information to
_____________________________________
____________________________________
Disadvantages of Link-State
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Processing requirements
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Bandwidth
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__________________________________________
___________________________________
Uses ____________________________________
_______________________________________
After initial flood, uses ____________________
__________________________________________
If LSA distribution to all routers is not done
correctly, link-state routing ______________
__________________________________
Configuring Routing
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Example
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Autonomous
system #
required for
IGRP, EIGRP
GAD(config)#router igrp 2
GAD(config-router)#network
172.16.0.0
Global config mode
Routing config mode
Necessary to enable the routing process to determine which
interfaces participate in the sending and receiving of routing
updates. Network addresses only listed here- NOT subnets
What are the routing protocols?
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RIP
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IGRP
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______________________________________________
______________ is used as the metric for path selection.
If the hop count is greater than ___, the packet is discarded.
Routing ________________________________, by default.
Cisco's ________________________________
________________________________________ are used
to create a composite metric.
Routing _________________________________, by default.
EIGRP
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Cisco’s ___________________________________________
Uses ______________________________.
Uses a _________________________________________.
Routing updates are broadcast every ____________ or as
________________________ changes.
More routing protocols…
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OSPF
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A ____________________________ used to
calculate the lowest cost to a destination.
Routing ___________________________ as
topology changes occur.
BGP
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It is a ______________________________
______________________________
Used ________________ or ISPs and clients.
Used to route ________________________
____________________________________
Summary comparison
DISTANCE-VECTOR
LINK-STATE
Views network topology from Gets common view of entire
neighbor’s perspective
network topology
Adds distance vectors from
router to router
Calculates the shortest path to
other routers
Frequent, periodic updates:
slow convergence
Event triggered updates: fast
convergence
Passes copies of routing
tables to neighbors
Passes link-state routing
updates to all routers in the
system.
One Lab for chapter 6
Configuring Static Routes
Lab 6.1.6