NETWORK Archives

Configuring a Cisco Router
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Configuring a Cisco Router

CISCO, NETWORK, VOIP

Configuring a Cisco Router

In the following sections, I’ll introduce the commands used to do basic router configuration.
You’ll use these commands (or should use them) on every router while you re configuring a Cisco router.

Setting a Router Hostname

Router#config t
Router(config)#hostname Kaya
Kaya(config)#

Setting Passwords

Here’s an example of setting all your passwords and then encrypting them in the plain configuration file:

Kaya#config t
Kaya(config)#line aux ?
<0-0> First Line number
Kaya(config)#line aux 0
Kaya(config-line)#password aux
Kaya(config-line)#login
Kaya(config-line)#line con 0
Kaya(config-line)#password console
Kaya(config-line)#login
Kaya(config-line)#exit
Kaya(config)#line vty 0 ?
<1-1180> Last Line number
<cr>
Kaya(config)#line vty 0 1180

CISCO, NETWORK, VOIP|

EIGRP

Enhanced Interior Gateway Protocol (EIGRP) is a proprietary hybrid routing protocol developed by Cisco Systems. EIGRP uses the same distance vector algorithm and distance information as IGRP. However, as its name implies, EIGRP has been enhanced in convergence properties and operating efficiency over IGRP. Principally, EIGRP has been enhanced to use more advanced features to avoid routing loops and to speed convergence time. In addition, EIGRP transmits the subnet mask for each routing entry, enabling EIGRP to support features such as VLSM and route summarization.

EIGRP Features

EIGRP provides advanced features over its predecessors IGRP and RIP:

Increased network width— With IP RIP, the largest possible width of your network is 15 hops. When IP EIGRP is enabled, the largest possible width is 224 hops.
Fast convergence— EIGRP uses an algorithm called the Diffusing Update Algorithm (DUAL). This algorithm guarantees loop-free operation at every […]

NETWORK|

IGRP

IGRP – Interior Gateway Routing Protocol

The Interior Gateway Routing Protocol (IGRP) is an advanced distance vector routing protocol. Because it is a Cisco-developed routing protocol, only Cisco devices can utilize this protocol for routing purposes. Like RIP, it is a classful protocol; meaning that it does not send the subnet mask with routing updates. So, it cannot support VLSMs.

A router running IGRP sends an update broadcast every 90 seconds, by default. When an update from the originating router is not received within three update periods (270 seconds), it declares a route invalid. After seven update periods (630 seconds), which include the three update periods, the router removes the route from the routing table.

IGRP advertises three types of routes:

Interior— Routes between subnets in the network attached to a router interface.
System— Routes to networks within an autonomous system. The router derives system routes from […]

NETWORK|

OSPF

The OSPF (Open Shortest Path First) protocol is one of a family of IP Routing protocols, and is an Interior Gateway Protocol (IGP) for the Internet, used to distribute IP routing information throughout a single Autonomous System (AS) in an IP network.

The OSPF protocol is a link-state routing protocol, which means that the routers exchange topology information with their nearest neighbors. The topology information is flooded throughout the AS, so that every router within the AS has a complete picture of the topology of the AS. This picture is then used to calculate end-to-end paths through the AS, normally using a variant of the Dijkstra algorithm. Therefore, in a link-state routing protocol, the next hop address to which data is forwarded is determined by choosing the best end-to-end path to the eventual destination.

Each OSPF router distributes information about its local […]

NETWORK|

Spanning Tree Protocol

Spanning Tree Protocol – STP

The Spanning Tree Protocol is a link management protocol that is designed to support redundant links while at the same time preventing switching loops in the network. It is quite useful and should be enabled on the switch interfaces.
STP has high convergence time; it can take up to one minute to converge and provide redundancy. A newer development is implemented to the STP protocol, called the Rapid Spanning Tree Protocol (RSTP). The latter retains all the tasks of STP whilst minimizing convergence time significantly.

Spanning Tree Protocol

The root bridge needs to be elected. Two fields combined together identify the root bridge: MAC address and Priority value. Without manual configuration all switches have the same priority therefore it is up to the MAC address to decide upon […]

NETWORK|