Routing Cdc

CISCO IOS

Introduction 

Cisco IOS (originally Inter network Operating System) is the software used on the vast majority of Cisco Systems routers and all current Cisco network switches.



IOS is a package of routing, switching, internetworking and telecommunications functions

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First IOS was written by William Yeager.

d p r o t o c o l

 t r a n s l a t i o n

   s e r v i c e s .

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T h e s e s e r v i c

Access Support The Cisco IOS software access support encompasses remote access and protocol translation services. These services provide connectivity to Terminals   Modems   Computers  Printers   Workstations



Various network configurations exist for connecting these network resources over LANs and wide area networks (WANs). LAN terminal service support is as follows:

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TCP/IP support for Telnet and rlogin connections to IP hosts.   TN3270 connections to IBM hosts.   LAT connections to DEC hosts.

 

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For WANs, Cisco IOS software supports four flavors of server operations:



Connectivity over a dial-up connection supporting

 - AppleTalk Remote Access (ARA)   - Serial Line Internet Protocol (SLIP)  - Compressed SLIP (CSLIP)  - Point-to-Point Protocol (PPP)  - X remote, Network Computing Device's (NCD) X Window System terminal protocol  

Asynchronous terminal connectivity to a LAN or WAN using network and terminal emulation software supporting Telnet, rlogin, DEC's Local Area Transport (LAT) protocol, and IBM TN3270 terminal protocol.  •Conversion of a virtual terminal protocol into another protocol, such as LAT-TCP or TCP-LAT communication between a terminal and a host computer over the network.  •Support for full Internet Protocol (IP), Novell Internet Packet Exchange (IPX), and AppleTalk routing over dial-up asynchronous connections.

Performance Optimization 

Cisco IOS software has two features that can greatly enhance bandwidth management, recovery, and routing in the network.



These two features are dial-on-demand access (DDA) and dial-on-demand routing (DDR). DDA is useful in several scenarios. These are  •Dial backup  •Dynamic bandwidth

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Management 

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Cisco IOS software supports the following protocols:   The two versions of Simple Network Management Protocol (SNMP) for IP-based network management systems   The Common Management Interface Protocol (CMIP)/Common Management Interface Service (CMIS) for OSI-based network management systems   IBM Network Management Vector Transport (NMVT) for SNA-based network management systems

o r k

Figure represents as core, distribution, and access. These a r c functional characteristics make up Cisco's router inter h i network architecture. t e c t u r e .

Core • The routers that comprise the core layer of the architecture are often referred to as the backbone routers. These routers connect to other core routers, providing multiple paths over the backbone between destinations. • These routers carry the bulk of WAN traffic between the distribution routers. Core routers are usually configured with several high-speed interfaces, as shown in Figure 2-2.

Distribution The distribution router may act solely as a distribution router for a region or campus, managing only the transmission of data between the core and the access layers.

Access • The outer layer of the architecture is the access layer. It is at this layer that end users gain access to the network resources connected by the routers. • A typical example for using access routers is in large buildings or campuses. As depicted in Figure 2-4, access routers connect workgroups and/or floor segments within a building to the distribution router. Access routers also provide remote dial-up connectivity for temporary connections.

IOS is responsible for..  Carrying

network protocols and functions  Connecting high speed traffic between devices  Adding security to control access and stop unauthorized network  Providing scalability for ease for network growth and redundancy

The 2501 router has two serial interfaces: one for WAN connection and one Attachment Unit Interface (AUI) connection for a 10Mbps Ethernet network connection. This router also has one console and one auxiliary connection via RJ-45 connectors.

Components in Router  Motherboard  MP

(Motorola )  SMPS  Chipset  Memory

 Dynamic

Ram – To store current configuration

 NVRAM

– To save the saved configuration

 Flash

– To store IOS in router

Booting Process of IOS  Boots

up from Flash ROM  Check for configuration in NVRAM  If saved configuration present in NVRAM  No contents in NVRAM, it starts up new configuration file.

 Console

Port  Auxiliary Port  VTY Line

IOS Configuration Mode  Dialogue

Configuration Mode  Command Line Interface

Command Line Interface  User

Execution Mode

 View

some basic statistics of the router  Cannot do advanced configuration  Privilege  View

execution mode or enable mode

all possible statistic of router  Do some changes which is applicable for that router only  Will not affect other configured router

 Global

Execution Mode

 Changes

 Line

which are common for the routers

Configuration Mode

 Console

Line  Auxiliary Line  Vty Line

 Interface

configuration Mode  Sub Interface configuration mode

2801 Cisco Router

Routing

Basic Commands 

USER EXECUTION MODE  ? -> help command.  S? -> Displays all commands which starts with ‘s’  Show clock -> Shows the clock settings  Show terminal -> Display history buffer size.  Show version - > Displays the version of your router.  Terminal History size <size> - >Allows you to change the history buffer size  Show history -> List last 10 commands typed by the user.

Privilege execution mode  Router

> enable - To enter into privilege mode from user execution mode

 Disable

– To exit to user execution mode from privilege mode

 Show

running-config – To show the contents of dynamic RAM

 Show

startup-config – To show the contents of NVRAM

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Show Flash – To show the contents of flash memory

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Show interface <E0/S0/S1> - To view status information about the particular interface.

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Show Ip interface brief – To view the status information of all interfaces of router.

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Show controllers [s0/s1] – To know about the DCE/DTE end of the serial interface



Copy running-config startup-config – To copy the contents from Dynamic RAM to NVRAM.

 Copy

startup-config running-config - To copy the contents of NVRAM to dynamic RAM

 Copy

Flash TFTP – To take back up copy of the contents in flash to TFTP server. It will prompt for TFTP server IP address

 Copy

startup-config TFTP – To take back up copy of NVRAM in TFTP

 Copy

running-config TFTP – To take back up copy of Dynamic RAM in TFTP.

 Copy

TFTP Flash – To restore IOS from TFTP to flash  Copy TFTP startup-config – To restore contents from TFTP to NVRAM.  Copy

TFTP running-config – To restore from TFTP to Dynamic RAM

 Configure

terminal/ configure t/ config t – To enter into your global execution mode.

Global Execution Mode  Hostname

[hostname] – change the

hostname.  Boot system TFTP  Boot system Flash – Boots IOS from flash.

 Enable

password <pass word> - Sets password for enable mode

 Enable

secret <password> - Encrypts the enable mode password

 Service

password-encryption – Encrypts all the line (console, vty, aux ) passwords.

 Hostname

router

- Setting Identity for the

Line configuration  (Config)#

Line console 0  (Config-Line)# password <password>  (Config-Line)# Login  (Config-Line)# exit

Auxiliary Line  (Config)#

Line aux 0  (Config-Line)# password <pass word>  (Config-Line)# Login  (Config-Line)# exit

Telnet Line  (Config)#

Line vty 0 4  (Config-Line)# password <pass word>  (Config-Line)# Login  (Config-Line)# exit

Router Interface  (Config)#

int E0  (Config-if)# ip address <subnet mask>  (Config-if)# no shutdown  (Config-if)# exit

Serial Interface  Config)#

int <S0/S1>  (Config-if)# ip address <subnet mask>  Config-if) # Clock rate (if DCE end)  (Config-if)# no shutdown  (Config-if)# exit

Troubleshooting Tools  Ping

 Traceroute  Telnet

Routing Definition  Routing

is used for taking a packet from one device and sending it to another device on a different network.

A

routing protocol is used by routers to dynamically find all the networks in the inter network and ensure that all routers have the routing table.

 Destination

address  Neighbor routers from which it can learn about remote networks  Possible routes to all remote networks  The best route to each remote network  How to maintain and verify routing information.

Three Types of Routing  Static

Routing  Default routing  Dynamic Routing

Static Routing

 Static

Routing occurs when you manually add routes in each routers routing table.

Syntax of Static Routing  Ip

route – Command used to create static route  Destination network – Network you are going to place in routing table  Next hop-address – The address of next hop router that will receive the packet and forward it to remote network  Administrative Distance – Static Routing has the default administrative distance of 1  Permanent – choosing the permanent option keeps the entry in routing table no matter what happens.

Default Routing  Used

to send packets with a remote destination network not in the routing table  Used in networks with single exit paths.

Syntax for default Routing  Router

(config)# Ip route 0.0.0.0 0.0.0.0

Dynamic Routing

 Dynamic

routing is where protocols find the networks and update routing tables on routers

Routing Protocols

 Distance

Vector Protocols  Link state Protocols  Hybrid Protocols

Distance Vector Protocols  Distance

Vector protocols find the best path to remote network by judging the distance.

 The

route with least number of hops to the network is determined to be the best route.

 They

send entire routing table to directly connected neighbors

 RIP

and IGRP are distance vector protocols

Difference Between RIP & RIPV2  RIP

V1-

 Distance

vector  Maximum hop count of 15  Classful  RIP

V2 –

 Distance

vector  Maximum hop count of 15  Classless  Administrative

Distance : 120

IGRP (Interior Gateway routing protocol)  Cisco

Proprietary protocol  Distance vector protocol  Maximum hop count 255 with default of 100  Updates routing messages every 90seconds by default  Uses Autonomous system number (1 – 65,535)  Uses Bellman Ford Algorithm  Administrative Distance - 100

IGRP  IGRP

–

 Can

be used in large inter networks  Uses an autonomous number for activation  Full route table update every 90seconds  Administrative distance of 100  RIP

–

 Works

best in small networks  Do not Use autonomous system number  Update every 30seconds  Administrative distance of 120

Verifying your configurations  Show

ip protocols

 Shows

you the routing protocols that are configured on your router

 Debug

ip Rip

 Sends

routing updates as they are sent and received on on the router.

 Debug

ip Igrp events

 Routing

 Debug

information that is running on the network

ip Igrp transactions

 Message

update.

request from neighbor routers asking for an

Link state Protocols  Link

state protocols send updates containing the state of their own links to all other routers on the network

 Maintains

three tables. 1) Keep tracks of directly connected neighbors. 2) determines the topology of entire internet work 3) Routing table

 Link

state know more about inter network than distance vector protocols

Hybrid Protocols  Combination

of both distance vector and link state protocols  EIGRP is an example for hybrid protocol

EIGRP Features  Cisco

proprietary protocol  Uses Autonomous number system  Unlike IGRP includes Subnet mask in its route updates  Hybrid Routing protocol  Maximum hop count of 255.  Administrative distance -90

Main Features of EIGRP  Supports

IP, IPX and Apple Talk  Considered Classless  Support for VLSM  Efficient neighbor discovery  Communication via Reliable Transport Protocol (RTP)  Best path selection via Diffusing Update Algorithm (DUAL)

Protocol Dependent Modules  EIGRP

supports multiple network layer protocols : IP, IPX and Apple talk  Different Network layer Protocols are supported using PDM’s.  PDM will maintain a separate series of tables containing the routing information that applies to specific protocol.  IP/EIGRP, IPX/EIGRP, Apple talk/EIGRP

Neighbor Discovery  Three

conditions that must be met for neighborship establishment  Hello

or ACK received  AS number match  Identical metrics

Neighbor Discovery  Link

state protocols tend to use Hello messages to establish neighborship  Only time EIGRP advertises its entire routing table is when it discovers a new neighbor and forms an adjacency with it through the exchange of hello packets  Both neighbors advertise their entire routing tables to one another  After learning its neighbors routes, only changes to the routing table are propagated from then on.

Terms to remember  Feasible

distance – This is the best metric along all the paths to a remote network

 Reported

Distance – This is the metric of remote network as reported by neighbor

 Neighbor

table – Each router keeps state information about adjacent neighbors

 Topology table

– It contains all destination advertised by neighboring routers.

Feasible Successor & Successor  Feasible

successor- It is a path whose reported distance is less than the feasible distance and it is considered a backup route.

 Successor

– A successor route is the best route to a remote network. A successor route is used by EIGRP to forward traffic to a destination and is stored in the routing table. It is backed by feasible successor that is stored in topology table.

Diffusing Update Algorithm  EIGRP

uses Diffusing Update Algorithm (DUAL) for selecting and maintaining the best path to each remote network.  Backup

route determination  Support for VLSM  Queries for an alternate route if no route can be found.

EIGRP Tables  Neighbor

table – Records information about routers with whom neighborship relationship have been found

 Topology

table – Route advertisements about every route in the inter network received from each neighbor

 Route

table- stores the route that are currently used to make routing decisions.

EIGRP Trouble shooting commands  Show

ip route – Shows the entire routing table

 Show

ip route eigrp – Shows only EIGRP entries in the routing table

 Show

ip eigrp neighbors – Show all EIGRP neighbors

 Show

ip eigrp topology – Shows entries in the EIGRP topology table

Show ip Eigrp Neighbor       

H – indicates the order in which the neighbor was discovered Hold Time – How long this router will wait for the Hello packet to arrive from a specific neighbor Uptime – indicates how long the neighborship was established Smooth round trip timer – Time it takes for a round trip from this router to its neighbor and back. RTO – Amount of time EIGRP waits before retransmitting a packet. Q – Outstanding messages in the queue Seq – Sequence number of the last update from that neighbor

Show ip Eigrp Topology P

(Passive) – Route is in passive state, which is good

 Active

State – Router has lost its path to this network and searching for replacement.

OSPF (Open Shortest Path First)  Open

standard routing protocol  Suitable for large network  Maintain multiple paths  Consists of areas and autonomous number  Minimizes routing update traffic  Supports VLSM  Has unlimited hop count  Uses Dijkstra algorithm.  Administrative Distance – 110

OSPF terms 

Router ID – It is an IP address used to identify the router. Highest IP address of all configured loop back interface. If no loop back interface, then Highest IP address of all active interface is considered.

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Neighbors – They are two or more routers that have an interface on a common network such as two routers connected point to point serial link

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Adjacency – It is a relationship between two OSPF routers that permits the direct exchange of route updates

Designated Router  Designated

Router – A designated router is elected whenever OSPF routers are connected to the same multi access network.

 They

are networks with multiple recipients.

Back up Designated Router

A

standby for the Designated router on multi – access links

Scenario  Router

A

 E0

– 192.168.1.70/26  S0 – 192.168.1.5/30  Router

B

 E0

– 192.168.1.40/27  S0 – 192.168.1.6/30  Router  E0

C

– 192.168.18/28  S0 -192.168.1.10/30

Syntax 





Router (config)# Router OSPF (PID – 1-65,535) Router (Config –Router)# network <Wild cardmask> Area ID – 0- 4.2million

Wild card Mask Table

 /25

/26  127 63

/27 /28 31 15

/29 7

/30 3

Verifying OSPF configuration  Show

ip OSPF – Displays OSPF information for one or all OSPF process running on the router

 Show

ip ospf interface – Displays all interface related OSPF information.

 Show

ip ospf neighbor – Regarding neighbor details. If DR or BDR exists that information will also be displayed

Access List  List

of conditions that categorize packets  Exercise control over network traffic  Implementing security policy  Basically packets are compared, categorized and acted upon accordingly  They can applied to either inbound or outbound traffic on any interface

Few important Rules 

Packets are always compared with each line of the access list in sequential order. Starts with the first line of the access list, then go to second line, 3 and so on.



Compared with line of the access list only until a match is made. Once the matches the condition on a line of the access list. The packet is acted upon and no other comparison takes place.



“Implicit Deny” at the end of each access list means that if a packet doesn’t match the condition on any of the lines in the access list, the packet will be discarded.

Types of Access List  Standard

Access List

 Uses

only the source IP address in an IP packet as the condition test  Based on the Source IP address  Configured near to destination.  Extended

Access List

 Condition

based upon Source IP, destination IP, protocols and port number.  Configured near to source.

Named Access List  Represents

set of statements by name  Can delete single statement

Standard Access List - Syntax  Router

(Config)# Access-List [Acl no] [ Permit/ Deny] [Source IP (W.M)]

 Router

(config)# int [E0/S0/S1]  Router (config-if)# ip access-group [Acl no] [in/out]  Acl

no : 1-99, 1300 - 1999

Access List – Named syntax  Router

(config)# ip access-list [Standard/extended] [name]  Router (config-std-nacl)# [permit/deny] [source IP (W.C.M)]

Standard Access List - Scenario

 

 

Router A – 192.168.1.0 Router A – 192.168.2.0 Router B – 192.168.3.0 Router B – 192.168.4.0

Configuration Router B (Config)# Access-List 10 deny 192.168.1.0 0.0.0.255 Router B (Config)# Access-list 10 deny 192.168.2.5 0.0.0.0 (or) Router B (Config)# Access-list 10 deny host 192.168.2.5 Router B (config)# Access-list 10 permit any

Interface Configuration Router B (config)# int E0 Router B (config)# Ip access-group 10 out.

Extended Access List - Syntax  Access-list

permit [IP/ICMP/Telnet] source [IP address] [wild card mask] destination [IP address] [wildcard card mask] eq port no

 Access

List number range 100 -199, 2000-2699

Extended Access List Configuration Router A (config)# Access-list 101 deny IP 192.168.1.0 0.0.0.255 192.168.3.0 0.0.0.255 Router A (config)# Access-list 101 deny ICMP host 192.168.2.1 host 192.168.3.5 Router A (config)# Access-list 101 permit any any

Interface Configuration  Router

A (Config)# int s0  Router A (config-if)# ip access-group 101 out

Switching  Layer

2 device  Uses MAC address for switching  Hardware based Switching called ASIC (Application specific integrated circuit)  Switches has private dedicated collision domains.  Independent bandwidth on each ports.

Bridge vs. Switch  Bridges

are software based while switches are hardware based (ASIC)  A switch is an multi port bridge  Dedicated bandwidth for each interface in switch, but in bridge the bandwidth is shared  Bridges and switches learn MAC addresses by examining the source address of each frame received  Both bridges and switches make forwarding decision based on layer 2 address

Three Function of Switch  Address

Learning – Switches and bridges remember the source hardware address of each frame received on an interface and they enter this information into MAC database called forward/filter table

Forward / Filter Decision  Frame

is received on a interface, the switch looks at the destination hardware address and finds the exit interface in the MAC database. The frame is only forwarded to that specified destination port

Loop Avoidance  If

multiple connections between switches are created for redundancy purpose, network loops occur. Spanning Tree protocol is used to stop network loops

LAN switches Types  Cut

through (Fast Forward) – Switch only waits for destination hardware address to be received before it looks up the destination address in the MAC filter table  Sometimes known as Fast Forward method.

Fragment Free  It

is commonly known as Commonly cutthrough

 The

switch checks first 64bytes of a frame before forwarding it for fragmentation.

Store and Forward  In

this mode, the complete data frame is received on the switch buffer, a CRC is run and if the CRC passes, the switch looks up the destination address in the MAC filter table

STP (Spanning Tree Protocol)  STP

uses Bridge packet Data Unit  Root Bridge – Bridge with best Bridge ID  Root bridge is elected using Bridge Priority number  Bridge with less priority number is selected as Root bridge, if priority number are the same then bridge with less MAC address is selected as Root Bridge  Default Priority Number : 32,768

Root Path  Root

bridges opens interfaces with root path and closes the designated path.  Root path is selected by lesser cost.

VLAN  Grouping

of interface of switch  Splits up single broadcast domain  Having multiple broadcast domain at layer2 itself  Broadcast message of one group will not be sent to other interface  VLAN 1 – Default VLAN, Native VLAN

VLAN configuration Syntax  Router#

VLAN Database  Router# VLAN Name  Router# EXIT  Router

(config)# int fa 0/1  Router (config-if)# switchport mode [access/trunk/dynamic]  Router (config-if)# switchport [mode] [vlan ID]  Router (config-if)# exit

VTP (VLAN Trunking Protocol)  VTP

are to manage all configured VLAN’s across a switched internetwork and to maintain the consistency through out that network.

 VTP

allows an administrator to add, delete and rename VLAN’s in the VTP domain.

 Accurate  Dynamic

tracking and monitoring of VLAN’S

reporting of added VLAN’s to all switches in the VTP domain

VTP Modes  Server

–

 There

is should be at least one server in your VTP domain to propagate VLAN information throughout the domain  The switch must be in server mode to be able to create, add or delete VLAN’s in a VTP domain.  Any changes made to switch in server mode will be advertised to the entire VTP domain.

VTP Mode - Client  Client  Switches

receive information from VTP

servers  They also send and receive updates  They cant make changes  None of the ports on a client switch can be added to a new VLAN before the VTP server notifies the client switch of the new VLAN.

VTP Mode - Transparent  Transparent  Switches

in the transparent mode can add and delete VLAN’s because they keep their own database.

VTP configuration  Switch

(config)# VTP domain [name]  Switch (config)# VTP password  Switch (config)# VTP mode [server/client/transparent]

Routing between VLAN’s

Connecting VLAN’s to router with single LAN interface

VLAN Identification Methods  Inter

Switch Link –

 This

is proprietary to Cisco switches and it is used for Fast Ethernet and Gigabit ether net links.

 IEEE

802.1Q –

 Created

by IEEE as a standard method of frame tagging it actually inserts a field into the frame to identify the VLAN.

Configuration  Router

(Config)# int fa 0/0.1/int fa 0/0.2  Router (Config- subif)# IP address 192.168.1.254 255.255.255.0  Router (config- subif)# no shutdown  Router (Config- subif)# encapsulation [dot 1q/ISL] [VLAN ID]  Router (Config- subif)# exit

 Router

(config)# int fa 0/0  Router (config- if)# no ip address  Router (config-if)# exit

Assigning Interface  Static Particular

interface fixed with VLAN ID. The system connected to that interface will have the VLANID of that interface only

 Dynamic The

interface of an VLANID can change, using VMPS server (VLAN management policy server)

Configuration  Switch

(config)# int fa 0/1  Switch (config-if)# VLAN membership [static/dynamic] [VLAN ID]  Switch (config-if)# exit

NAT (Network Address Translation)  Translates

the private address within the network into public address before any packets are forwarded to another network.

 Inside

Network – Set of networks that are subject to translation  Outside Network – Refers to address, usually located on the internet

Different Types of NAT  Static

NAT  Dynamic NAT  PAT

Static NAT  Designed

to allow one to one mapping between local and global address.  One real Internet IP address for every host on your network.

Configuration – Static NAT   

Router (config)# IP NAT inside Source static <private IP address> Example: IP NAT inside source 192.168.1.1 200.1.1.10 When packets are sent from system to INTERNET server  



Router (config)# int E0 Router (config)# IP NAT inside

When packets are received from INTERNET server to system  

Router (config)# int S0 Router (config)# IP NAT outside

Dynamic NAT  Designed

to map an unregistered IP address to a set of registered IP address.

 For

example – 6IP address for n number of systems.

Configuration – Dynamic NAT  Router

(config)# Access-list [acl no] permit [private network IP address] [wild card mask]

 Router

(config)# IP NAT pool [pool name] [start IP address] [end address] network [subnet mask]

 Router

(config)# IP NAT inside source list [acl no] pool [pool name]

Example 

In global Configuration mode :



Access-list 1 permit 192.168.1.0 0.0.0.255 IP NAT Pool HCL 200.1.1.9 200.1.1.14 network 255.255.255.248 IP NAT Pool inside source list 1 Pool HCL

     

Int E0 NAT inside Int S0 NAT outside

Port Address Translation  Maps

multiple unregistered IP address to single registered IP address by using different ports.

 By

using PAT (NAT overload), you can have thousands of users connect to the Internet using only one real global IP address

PAT configuration  In

global configuration mode:

 Access-list

1 permit 192.168.1.0 0.0.0.255  IP NAT Pool HCL 200.1.1.5 200.1.1.5 255.255.252  IP NAT inside source list 1 port HCL overload. Int E0 NAT inside Int S0 NAT outside