What are routers (Ponta)

1
Introduction

• What are routers (Ponta)
• Data Conversion (Adrian)
• Routing (Albert)
• Routers (Jordan)
• Router Architecture (Victor)

2
Routers vs. Computer

• What is a computer?
• A general purpose machine that takes an input
  translates the input under software control and
  gives an output.
• A router is also a computer
• not a general purpose machine
• Main purpose is to route data

3
Networks

• Todays networks are large masses of routers
• Routers take any form of data such as email,
  web-browser requests, and file transfers and
  deliver them to the appropriate destinations.
• The internet is a large network of interconnected
  routers.

4
Routing in a nutshell

• Routers work by reading the IP address of data
  packets and determines the correct source and
  destination for the packet.
• The router can also discover the best way to get
  the packet to its destination.

5
Routing in a nutshell (cont.)

• Routers take requests from their local users and
  forward those requests to the appropriate host.

6
Routing

• Routing is the process that allows data to travel
  from one host to another
• Routing is responsible for the making the
  Internet work.

7
Without Routers

• Every computer would have to be connected
  together
• Users would need to know
• the address of every website they wanted to visit
• All the computers you would need to pass through
  to get to the destination computer.

8
Accessing Websites

• You enter a URL address in to your web browser
  (e.g. Internet Explorer, Netscape Navigator,
  etc.), e.g, http//www.csun.edu
• The browser sends a message to the router
• The message notifies that you want to see the
  information stored at www.csun.edu
• The process begins

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Internet Explorer
10
Netscape
11
Address Conversion

• DNS servers translate the alphanumeric URL,
  www.csun.edu, address to an IP address
  130.166.1.55
• Packets are sent to the routers that read this
  address

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Routing Packets

• Each router examines the packet
• Determines the IP address
• Matches the information against its own routing
  table.
• Chooses which port to route it out of

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Routing Table

• A two column table
• First column identifies each router in the
  network
• Second column lists the router to which each
  router should send data to

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Routing Table

• Router examines packet
• If exact match, forwards the message
• If there is no match, it runs though table again,
  looking for a match
• If still no match, router sends the packet out of
  the default next-hop address

15
Routing Table

• Router sends an ICMP() host unreachable or
  network unreachable message back to sender
  ultimately if no match is found.
• Difficult part of routers job is not how it
  routes, but how it builds up its table

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Routing Table Example
Source Destination Next Hop
A A A A B B B C D E F G B B D B or D C or E C
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Routing Packets

• This process continues until the request finally
  reaches www.csun.edu

18
Routing

• The routing tables have been keeping track of the
  path to the destination.
• The routing path is now known by the initial
  router.

19
Routing Algorithms

• Routing algorithm
• complex set of rules that take into account a
  variety of factors
• Determines what is the best via routing algorithm
• Selects the best path between the source and
  destination machine

20
Routing Issues
21
Flooding the Network

• Early routers were slow
• The networks they ran on were equally
  low-powered, with little bandwidth
• Isolated in that they did not exchange routing
  tables
• As a result routers forwarded data by flooding
  every path with packets

22
How can we solve this?

• Backward learning-router remembers the source
  addresses of all incoming packets and notes the
  physical interface it came in on
• Static Routing
• Rely either on a human or host computer to make
  these decisions
• Source routing-end hosts place information in
  every packet they place on the network

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Centralized vs. Decentralized
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Centralized Routing

• All routing decisions are made by one central
  computer or router
• Typically used in host computers
• All computers are connected to the central
  computer

25
Decentralized Routing

• All computer or routers in the network make their
  own routing decisions
• In larger networks, routing table is developed by
  the network manager
• In smaller networks, routing table is developed
  by one individual
• Most decentralized routing protocols can
  automatically adapt to changes in the network
  configuration

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Static vs. Dynamic Routing
27
Static Routing

• Routing decisions are made in a decentralized
  manner
• When new computers are added to network, they
  announce their presence
• Commonly used in networks that have few routing
  options that seldom change

28
Dynamic Routing

• Routing decisions are made in a decentralized
  manner by individual computers
• Used when there are multiple routes through a
  network
• Routes messages over the fastest possible route

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Dynamic Routing

• Distance vector dynamic routing
• Routers count the number of hops along a route.
• Routers periodically exchange information on the
  hop count

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Dynamic Routing

• Link state dynamic routing
• Rather than knowing a routes distance, link
  state routing tries to determine how fast each
  possible route is
• Routers periodically exchange this information to
  other routers in the network
• Preferred over distance vector protocols because
  they converge quicker

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Dynamic Routing-Drawbacks

• Requires more processing by each computer or
  router in the network
• Transmission of routing information wastes
  network capacity.

32
Connectionless Routing

• Used when a message can fit into one single
  packet
• Each packet is routed independently
• A router must make a decision for each packet
• Used by UDP (User Datagram Protocol) to send
  short control messages

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Connection-Oriented Routing

• Sets up a virtual circuit between the sender and
  receiver
• Packets from the same message use the same route

VC1
VC2
34
Router Types

• Home Routers
• Small Organization and Office Routers
• High End Routers

35
Home Routers

• Usually simple
• Examples includes
• Linksys, Cable/DSL, 10/100 Ethernet backbone
• Features
• Voice over IP telephone installed by Netphone.

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D-LINK-614

• 22mbps Air Plus is twice as fast as the usual
  (11-mbps) 802.11b connection
• Utilizes Texas Instruments patented Digital
  Signal Processing
• Offers 256-bit encryption
• the strongest available
• Deep firewall configuration options.
• Firewall features are easy to implement
• Example Can designate particular computers as
  WEB servers or FTP servers which are visible to
  the Internet

37
D-LINK-614
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Small Organization and Office Routers

• Slightly larger routers
• Do little more than home router
• These routers enforce rules concerning security
  for the office network.

39
3-Com-Superstack

• Provides
• Low equipment costs
• Dial-in/dial-out
• Frame Relay
• Lease Line PPP Connection

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3-Com Superstack cont.

• Contains
• Three stackable components
• That provides multi-protocol remote access server
  
• Full function WAN router technology for small and
  medium sized business.
• Offers secure access Authentication

41
3-Com Superstack cont.

• In addition
• it can proxy or relay IP address to another
  central server.
• Simplifies network administration
• Enhances the mobility of both remote and local
  users.

42
High-End Routers

• Largest routers
• Handle million of packets every second
• Work to configure the network efficiently
• Large stand alone systems

43
Nortel Networks

• High end routers manufacturer
• Provides large high performance, scalable routing
  devices.
• Backbone Node and Backbone Concentrator Node

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Benefits of the Nortel Networks

• Enhance network performance
• High Network availability
• Network investment protection

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IBM 2210 Nways Multiprotocol

• Provides network solutions for a range of
  applications
• This allows

• System administrators to build and manage
  scalable Web Servers.
• Superior to Domain Name Servers round
  robin-querying

46
Router Architecture
47
Router Memory

• Flash
• ROM
• Cache
• RAM

48
Router Memory

• Flash
• Location where the basic boot image is stored.

49
Router Memory

• ROM
• Initializes the processor hardware and boots the
  operating system software.
• Runs when the router is powered up or reset

50
Router Memory

• Cache
• Primary
• Primary cache is closest to the processor core
  and has the fastest access
• Secondary
• Secondary cache has slower access than primary
  cache, but faster access than tertiary cache.
• Trietary
• Slowest of all cache but faster than RAM

51
Router Memory

• RAM Random Access Memory
• SDRAM
• Synchronous Dynamic Random-Access Memory
• Runs at 133MHz
• DDR-SDRAM
• Double Data Rate Synchronous Dynamic
  Random-Access Memory
• Runs at 266MHz
• NVRAM
• nonvolatile random-access memory
• Uses lithium batteries to maintain its contents
  when power is removed

52
Router Memory

• RAM Packaging
• SIMM
• Single In-line Memory Module
• DIMM
• Dual In-line Memory Module
• SODIMM
• Small Outline Dual In-line Memory Module.

53
Router Ports

• Ethernet
• refers to the family of local-area network (LAN)
  products covered by the IEEE 802.3 standard
• 10/100/1000 Mbps
• ISDN
• Integrated Service Digital Network
• Communication protocol offered by telephone
  companies that permits telephone networks to
  carry data, voice, and other source traffic.

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Router Ports

• T3
• Digital WAN carrier facility
• Transmits DS-3-formatted data at 44.736 Mbps
  through the telephone switching network.
• OC-3
• Operates at 155 Mbps
• Provides the highest available interface
  bandwidth for packet-based traffic

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Cisco 7200
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Cisco 7200
Modules Cisco 7204VXR Cisco 7206VXR
Configurable Slots 4 6
Ethernet (10BASE-T) Ports 32 48
Ethernet (10BASE-FL) Ports 20 30
Fast Ethernet (TX) Ports 4 Up to 6
Fast Ethernet (FX) Ports 4 Up to 6
EtherSwitch Port Adapters 2 2
100VG-AnyLAN Ports 4 Up to 6
FDDI (FDX, HDX) Ports 0 0
ATM Ports (T3, OC-3) 4, 4 Up to 6, 4
Packet over SONET 2 2
ATM-CES Port Adapters (Data, Voice, Video), Dual-Wide 1 1
Token Ring (FDX, HDX) Ports 16 24
Synchronous Serial Ports 32 48
ISDN BRI Ports (U, S/T) 16, 32 24, 48
ISDN PRI, Multichannel T1/E1 Ports 32 48
Multichannel T3 Ports Up to 4 Up to 6
HSSI Ports Up to 8 Up to 12
Packet over T3/E3 Ports (Integrated DSU) Up to 8 Up to 12
IBM Channel Interface Ports (ESCON and Parallel) 6 6
VPN Acceleration Module 1 1

• Two models
• 7204VXR
• 7206VXR
• Modules based

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Cisco 7200 Processors

• 4 types of processor units
• NPE 225
• NPE 400
• NSE-1
• NPE-G1

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Cisco 7200 Processors

• NPE 225

• NSE-1

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Cisco 7200 Processors

• NPE-G1

• NPE 400

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Cisco 7200 Memory Configuration
NPE-225 NSE-1 NPE-400 NPE-G1
Microprocessor RM5271 262MHz RM7000 262MHz RM7000 350MHz BCM1250 700MHz
Memory SDRAM DIMM Max 128 SDRAM DIMM Max 256MB SDRAM SODIMM Max 512MB SDRAM SODIMM Max 512MB
Primary Cache 32K Instr. 32KB Data 16KB Instr. 16KB Data 16KB Instr. 16KB Data 16KB Instr. 16KB Data
Secondary Cache 2MB 256KB 256KB Fixed 512KB
Tertiary Cache 2MB Fixed 4MB
Boot ROM 512KB 512KB 512KB 512KB
NVRAM 512KB
Flash Memory 16MB 16MB 16MB 16MB
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THE END