Title: What are routers (Ponta)
1Introduction
- What are routers (Ponta)
- Data Conversion (Adrian)
- Routing (Albert)
- Routers (Jordan)
- Router Architecture (Victor)
2Routers 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
3Networks
- 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.
4Routing 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.
5Routing in a nutshell (cont.)
- Routers take requests from their local users and
forward those requests to the appropriate host.
6Routing
- Routing is the process that allows data to travel
from one host to another - Routing is responsible for the making the
Internet work.
7Without 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.
8Accessing 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
9Internet Explorer
10Netscape
11Address 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
12Routing 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
13Routing 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
14Routing 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
15Routing 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
16Routing 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
17Routing Packets
- This process continues until the request finally
reaches www.csun.edu
18Routing
- The routing tables have been keeping track of the
path to the destination. - The routing path is now known by the initial
router.
19Routing 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
20Routing Issues
21Flooding 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
22How 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
23Centralized vs. Decentralized
24Centralized 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
25Decentralized 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
26Static vs. Dynamic Routing
27Static 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
28Dynamic 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
29Dynamic Routing
- Distance vector dynamic routing
- Routers count the number of hops along a route.
- Routers periodically exchange information on the
hop count
30Dynamic 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
31Dynamic Routing-Drawbacks
- Requires more processing by each computer or
router in the network - Transmission of routing information wastes
network capacity.
32Connectionless 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
33Connection-Oriented Routing
- Sets up a virtual circuit between the sender and
receiver - Packets from the same message use the same route
VC1
VC2
34Router Types
- Home Routers
- Small Organization and Office Routers
- High End Routers
35Home Routers
- Usually simple
- Examples includes
- Linksys, Cable/DSL, 10/100 Ethernet backbone
- Features
- Voice over IP telephone installed by Netphone.
-
36D-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
37D-LINK-614
38Small Organization and Office Routers
- Slightly larger routers
- Do little more than home router
- These routers enforce rules concerning security
for the office network.
393-Com-Superstack
- Provides
- Low equipment costs
- Dial-in/dial-out
- Frame Relay
- Lease Line PPP Connection
403-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
413-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.
42High-End Routers
- Largest routers
- Handle million of packets every second
- Work to configure the network efficiently
- Large stand alone systems
43Nortel Networks
- High end routers manufacturer
- Provides large high performance, scalable routing
devices. - Backbone Node and Backbone Concentrator Node
44Benefits of the Nortel Networks
- Enhance network performance
- High Network availability
- Network investment protection
45IBM 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
46Router Architecture
47Router Memory
48Router Memory
- Flash
- Location where the basic boot image is stored.
49Router Memory
- ROM
- Initializes the processor hardware and boots the
operating system software. - Runs when the router is powered up or reset
50Router 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
51Router 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
52Router Memory
- RAM Packaging
- SIMM
- Single In-line Memory Module
- DIMM
- Dual In-line Memory Module
- SODIMM
- Small Outline Dual In-line Memory Module.
53Router 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.
54Router 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
55Cisco 7200
56Cisco 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
57Cisco 7200 Processors
- 4 types of processor units
- NPE 225
- NPE 400
- NSE-1
- NPE-G1
58Cisco 7200 Processors
59Cisco 7200 Processors
60Cisco 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
61THE END