Enabling Routing Protocols

gascitytankNetworking and Communications

Oct 28, 2013 (4 years and 12 days ago)

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© 2007 Cisco Sy stems, Inc. All rights reserv ed.

Cisco Public

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Version 4.1

Routing

Working at a Small
-
to
-
Medium Business or ISP


Chapter 6


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© 2007 Cisco Sy stems, Inc. All rights reserv ed.

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Objectives


Describe the purpose and function of dynamic routing
and the protocols used to implement it.


Configure RIPv2 dynamic routing using the Cisco
IOS.


Describe the use of exterior routing protocols across
the Internet.


Enable BGP on a customer site router.

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Enabling Routing Protocols


Routing tables contain locally connected
networks


Routers use routing tables to determine routes


Routes can be statically assigned or
dynamically learned through routing protocols

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© 2007 Cisco Sy stems, Inc. All rights reserv ed.

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Enabling Routing Protocols


Components of a route: destination value,
subnet mask, gateway, route cost or metric

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© 2007 Cisco Sy stems, Inc. All rights reserv ed.

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Enabling Routing Protocols


Directly connected routes


Static routes


Dynamically updated routes


Default route

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© 2007 Cisco Sy stems, Inc. All rights reserv ed.

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Enabling Routing Protocols


Static routes are manually configured


Static routes are suitable for small networks
with few changes

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Enabling Routing Protocols

Characteristics of distance vector protocols:


Routers share copies of routing tables


Distance metric can be based on hops, cost,
bandwidth, speed, delay or reliability


Vector is the address of the next hop along a
route

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Enabling Routing Protocols

Routing Information Protocol (RIP):


RFC 1058


Distance vector using hop count metric


Updates every 30 seconds

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Enabling Routing Protocols

Enhanced Interior Gateway Routing Protocol:
(EIGRP)


Enhanced distance vector protocol


Uses a variety of metrics


Cisco
-
proprietary

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Enabling Routing Protocols

Characteristics of link
-
state protocols:


Full database of distant routers and
interconnections


Link
-
state advertisements


Topological database


SPF algorithm

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Enabling Routing Protocols

Open Shortest Path First (OSPF):


Non
-
proprietary


Link
-
state


RFC 2328


Advanced protocol

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Enabling Routing Protocols

Criteria for choosing routing protocols:


Ease of management


Ease of configuration


Efficiency



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© 2007 Cisco Sy stems, Inc. All rights reserv ed.

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Enabling Routing Protocols


Describe and implement RIP routing on an
integrated router


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Exterior Routing Protocols


The Internet is divided into autonomous
systems


AS: a set of networks controlled by a single
administration using the same internal routing
policy


Each ISP is an AS

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Exterior Routing Protocols


Interior gateway protocols (IGPs) exchange
routing information within an AS or individual
organization


Exterior gateway protocols (EGPs) exchange
routing information between autonomous
systems

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Exterior Routing Protocols


Each AS uses dedicated border gateway
routers to route packets across the Internet

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Exterior Routing Protocols


ISPs use exterior routing protocols to forward
or control local and/or transit traffic


Exterior protocols enforce policies and support
reliability


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Exterior Routing Protocols

Configuring Border Gateway Protocol (BGP):


Configure the AS number


Identify ISP neighbor router


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© 2007 Cisco Sy stems, Inc. All rights reserv ed.

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Summary


All routers make routing decisions by looking up information stored
in their routing tables.


Routes can be statically assigned by an administrator, or
dynamically learned by the router via a routing protocol.


Routing protocols use either distance
-
vector or link
-
state
algorithms to calculate the best routes to each destination.


Criteria such as ease of management, ease of configuration, and
efficiency must be considered when selecting a routing protocol for
use within an organization.


Organizations are also called Autonomous Systems.


Between Autonomous Systems, Exterior Gateway routing
protocols control the flow of traffic.


ISPs handle Internet traffic through the use of routing policies.


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