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Routing and Routing Protocols:
Routing Static
© 2004, Cisco Systems, Inc. All rights reserved.
1
Objectives
Route Types
Introducing Routing
•
In order to forward packets correctly, routers must learn
the path to remote networks.
•
There are methods by which a router can learn these
routes:
1.
Dynamic routing - information is learned from other routers, and
routing protocols adjust routes automatically.
2.
Static routing - network administrator configures information about
remote networks manually. They are used to reduce overhead and
for security.
– Because of the extra administrative requirements, static routing
does not have the scalability of dynamic routing.
– In most networks static routes are often used in conjunction with
a dynamic routing protocol.
Static Routes
•
Static routes are manually configured using the ip route
command
•
The IP route command can set the next hop by specifying either:
1.
The outgoing interface, or
2.
The next hop IP address of the adjacent router
See examples in next slides
•
Command Format
ip route network_address network_mask next_hop | interface_admin_dist
1. Specifying the Outgoing Interface
2. Specifying the Next-hop IP Address
Administrative Distance
•
The Administrative Distance is the trustworthiness of the source of the
route.
– The router by default assigns a Administrative Distance of 1 to static
routes.
– It is assumed that if the administrator takes the time to figure out what
route the packet should take then this routing information must be
very reliable
– Only directly connected routes have a default Administrative Distance
that is trusted more (directly connected default Administrative
Distance is 0).
•
Administrative Distance should not be confused with the Metric of the
route. The metric of the route is how good an individual route is
– When a router selects a route to a particular destination to put in the
routing table, it first examines the Administrative Distance of all the
routes available to that destination
– If it has alternate routes to the same destination it will use the route
with the lowest Administrative Distance
Configuring Static Routes
•
We can configure static routes to all destinations
Non-directly Connected Networks
•
Or we can set a default route to be used for any destination that does not have
a routing table entry
Verifying Static Route Configuration
• The command show running-config is
used to view the active configuration in RAM
to verify that the static route was entered
correctly.
• The show ip route command is used to
make sure that the static route is present in
the routing table
Static Routes
Static routes between networks are manually configured by an administrator.
Static routes are added with the following command:
Router(config)# ip route 192.168.2.0 255.255.255.0 E0
Network Address
Subnet Mask
Interface
This command sets a default route on a router: ip route 0.0.0.0 0.0.0.0 [next-hop-address | outgoing interface]
Router(config)#ip route 0.0.0.0 0.0.0.0 192.168.1.1
Static routes to next hop addresses have administrative distance of 1.
Static routes out interfaces have an administrative distance of 0.
You can specify a non-default administrative distance for a static route:
Router(config)# ip route 0.0.0.0 0.0.0.0 192.168.1.1 130
Default routes are used to route packets with destinations that do not match any of the other
routes in the routing table
Troubleshooting Static Route Configuration
• The show interfaces command
• The ping command
• The traceroute command
Verifying / Troubleshooting the Static Route
Verifying static route configuration
•
After static routes are configured it is important to verify that they are present in
the routing table and that routing is working as expected
•
The command show running-config is used to view the active configuration in
NVRAM to verify that the static route was entered correctly
•
The show ip route command is used to make sure that the static route is present
in the routing table
Troubleshooting static route configuration
•
The show interfaces command can be used to check the state and configuration
of the interface that is to be used for the route gateway
•
The ping command is used to determine if end-to end connectivity exists
•
If an echo reply is not received after a ping, traceroute will be used to determine
which router in the route path is dropping the packets
The show ip route Command Output
The ping and traceroute Commands
Routed Versus Routing Protocol
Autonomous Systems >> pengelolaan jaringan secara sendiri
AS 10
AS 20
Autonomous Systems
• Autonomous Systems divide the global internetwork into smaller,
more manageable networks.
• An Autonomous System is a collection of networks under a common
administration (a single organisation, ISP or systems administrator)
and sharing a common routing strategy.
• Typically the world wide organisation ICANN, the ISP, or the
administrator assigns a unique AS number to the Autonomous
System.
• The Autonomous System number uniquely distinguish it from other
Autonomous Systems around the world.
• Each Autonomous Systems has its own set of rules and policies.
Routing Protocols
Protocol
RIP
IGRP
EIGRP
Overview
Features
Distance vector, hop count metric, maximum 15 hops,
broadcasts updates every 30 secs.
Cisco proprietary distance vector, bandwidth / load / delay /
reliability composite metric, broadcast updates every 90 secs.
Cisco proprietary, enhanced distance vector (hybrid), load
balancing, uses DUAL to calculate shortest path.
Routing updates are triggered by topology changes.
OSPF
Link-state, open standard, Uses SPF algorithm. Routing updates
are sent as topology changes occur.
BGP
Distance vector exterior routing protocol, used between ISPs, used
to route traffic between ASs.
Summary