NT1210 Introduction to Networking - YPW · The Internet as a Network of Networks SiIt td Et iSecuring Internet edge: Enterprises use many security measures and devices to make Internet

NT1210 Introduction to Networking

Unit 9: Chapter 9, The InternetChapter 9, The Internet

ObjectivesObjectives

Id tif th j d d t k h ld f tIdentify the major needs and stakeholders for computer networks and network applications.

Identify the classifications of networks and how they areIdentify the classifications of networks and how they are applied to various types of enterprises.

Explain the functionality and use of typical networkExplain the functionality and use of typical network protocols.

Analyze network components and their primary functions in a typical data network from both logical and physical perspectives.

2


Diff ti t j t f LAN d WANDifferentiate among major types of LAN and WAN technologies and specifications and determine how each is used in a data network.

Explain basic security requirements for networks.

Plan and design an IP network by applying subnettingPlan and design an IP network by applying subnetting skills.

Assess a typical group of devices networked to another group of devices through the Internet, identifying and explaining all major components and their respective functionsfunctions.

3


R l t h diff t t h l i d tRelate how different technologies are used to access the Internet.

Define how IP routing is used in the Internet to moveDefine how IP routing is used in the Internet to move data from source to destination.

Define classless routing.Define classless routing.

Evaluate the need for NAT, PAT, CIDR, and IPv6 in current networks.

4

The Internet as a Network of Networks

Figure 9-1Internet Access Links from TCP/IP Networks, Large and Small5


I t t S i P id (ISP ) t I t tInternet Service Providers (ISPs) create Internet core

Creates physical network for IP packets to travel between enterprises and individual usersbetween enterprises and individual users

Figure 9-2The Internet Core, with Multiple Service Providers6


C ti t iConnecting enterprises

Figure 9-3Typical Organizations Whose TCP/IP Networks Connect to the Internet7


C ti t I t t dConnecting to Internet edge: Part of Internet topology between ISP and customer (sits at edge of both networks)

Figure 9-4Comparing an Enterprise and ISP Network8


F t k l tiFrom network layer perspective: Internet access link acts like any other WAN link between yrouters

Figure 9-5T3 Serial Link Connection to the Internet9


S i I t t d E t iSecuring Internet edge: Enterprises use many security measures and devices to make Internet connection more secure

Firewalls Intrusion Prevention Systems (IPS)

E l Fi ll it i thExample: Firewall sits in path that all packets take; IPS sits outside path so LAN switch pforwards packets to IPS and it analyzes packets and watches for signs of problemsfor signs of problems

Figure 9-6An Example Case of Using an Enterprise Firewall and IPS10


T i l l f t i fi llTypical rules for enterprise firewallA. (Default): Allow inside clients to reach outside

servers in Internet

B. (Default): Disallow outside clients from sending packets to inside servers, unless another rule allows packetanother rule allows packet

C. (New Rule): Allow outside clients to connect to the two public

b i DMZweb servers in DMZ

Example: Two attempts from users in Internet to connect to two different servers inInternet to connect to two different servers in enterprise

Figure 9-7Firewall Allowing Connections to Public Web Servers Only11


E h WAN t h l t ti b tEach WAN technology creates connection between user’s device and ISP

WAN connection mightWAN connection might connect user’s device directly to WAN or may use router (not shown in example)

Figure 9-8Four Main Options for Individual Internet Access12


Connecting Customers to ISP Point of Presence (PoP):Connecting Customers to ISP Point-of-Presence (PoP): Each ISP has to create connections

Connections between ISP’s customers d ISP P Pand ISP PoP

Connections between all ISP’s PoPs create ISP’s own network and allow all of customers to send packets to one anotherConnections to other ISP networks form Internet core which allows all Internet hosts everywhere to send packets to each other

To create effective Internet access service, ISP needs number of PoPs in different locations

Figure 9-9ISP Point-of-Presence (PoP) Concept with Customer Access13


E l T i l P P ith t i di tExample: Typical PoP with access routes using direct link to distribution router which connects to rest of ISP’s network

Figure 9-10Example of Dividing Responsibilities Inside an ISP PoP14


C ti P P t t ISP t k lConnecting PoPs to create ISP network exampleISP might put two more routers at centralized site and use 10-Gbps Ethernet or SONET pequivalent (called OC-192) on all links (center of graphic)

Figure 9-11Connecting All ISP PoP Routers to Create an ISP TCP/IP Network15


ISP k t th t t I t tISPs work together to create Internet core

Internet core connects all ISPs to all otherall ISPs to all other ISPs (sometimes directly; sometimes indirectly)

Result: All ISPs can send packets to hosts connectedpackets to hosts connected to every other ISP

Figure 9-12Creating the Internet Core: Connections Between Large ISPs16


Ti 2 ISP l ti t Ti 1 ISP fTier 2 ISPs rely on connections to Tier 1 ISPs for some of their connections to Internet

Tier 2 ISPs connect to one orTier 2 ISPs connect to one or more Tier 1 ISPs rather than connecting to ALL Tier 1 ISPs across globe

Figure 9-13Connectivity Between Tier 1 and Tier 2 ISPs17


Other providers of Internet services: Companies whoOther providers of Internet services: Companies who provide services available through Internet

Web hostingSearch enginesSocial mediaCloud services

Figure 9-14Other Service Providers Connected to the Internet18


Oth id f I t t iOther providers of Internet services Web Hosting: Customer picks URL for its website, creates content for website, and puts website files onto servers that sitcontent for website, and puts website files onto servers that sit at web hosting company

Search Engine: Computers inside service provider’s network have programs that act like web browsers systematicallyhave programs that act like web browsers, systematically getting copy of every web page they can find on Internet

Social Media: Service provider that builds web servers that f f (provide framework for users to add their own content (text,

photos, video, apps)

Cloud Services: Large variety of services available through g y gInternet

19


Web hosting example: Company websiteWeb hosting example: Company website (www.example.com) exists on servers owned by web hosting company

When user browses to www.example.com, packets flow to/from servers at web hosting company

Figure 9-15Hosting a Web Site at a Web Hosting Service, Not in the Enterprise’s IP Network20

Internet Access Technologies

Ph li d l d (L 1 d 2) I t tPhone line and analog modem (Layers 1 and 2) Internet access: When customer calls, Telco passes call to ISP PoP over phone line not being used at momentp gExample: Two ISP customers with analog modems

If ISP wants to support many concurrent users in PoP, they need many modemsneed many modemsOnce dialed in, users’ PCs can send and receive bits with ISP through R1

Figure 9-16Two ISP Customers Using Analog Modems and Analog Phone Lines21


PPP d DHCP T th th h l t ’ PCPPP and DHCP: Together they help customer’s PC learn its public IP address, subnet mask, default gateway, and IP addresses of DNS servers so PCs can g y,access Internet

Figure 9-17Role of PPP on a Analog Dial-up Circuit to an ISP22


U i l h li f I t tUsing analog phone lines for Internet accessAnalog modems use symmetric speeds: Upstream speed (from customer to ISP) same as downstream speed (from Internet to customer)

For most Internet applications, more bytes flow downstream than upstreamp

Asymmetric service with faster downstream speeds actually works better

23


U i l h li f I t tUsing analog phone lines for Internet access

Name Analog ModemPhysical link Telco local loop Always on? No Allows voice at same time over same medium? No Asymmetric? (Faster downlink possible?) No Approximate real-life downlink speeds 56 Kbps

Table 9-1Comparison Points: Analog Modem24


Di it l t h l i f T l I t t d S iDigital technologies from Telcos: Integrated Services Digital Network (ISDN) and Digital Subscriber Line (DSL)( )

DSL requires changes to devices at end of local loop cabling, including device in Telco COTraditional CO voiceTraditional CO voice switch does not know what to do with DSL higher frequencies, g e eque c es,so CO needs DSL Access Multiplexer(DSLAM) for DSL frequencies

Figure 9-18DSL Using Multiple Frequencies over a Single Local Loop25


Li litt ll b th l h d DSL dLine splitter allows both analog phone and DSL modem to connect to same phone line and transmit simultaneouslyy

Figure 9-19Home Cabling and Devices for DSL26


DSLAM uses Frequency Division Multiplexing (FDM) to separate voice and data frequencies in same electrical signalgDSLAM does not process data or voice; just passes data or voice off to

t d icorrect device (router or traditional voice switch)

Figure 9-20DSLAM Multiplexes Voice to the PSTN and Data to the ISP27


DSL D t Li k t l PPP (P i t t P i tDSL uses Data Link protocol PPP (Point-to-Point Protocol) to move data (IP packet encapsulated in PPP frame) to DSLAM which then moves PPP frame to ISP )router

Figure 9-21PPP Encapsulated IP Packets Going from Home to ISP Router over DSL28


Diff d i il iti b t l d DSLDifferences and similarities between analog and DSL modems

N A l Ci it DSLName Analog Circuit DSL

Physical link Telco local loop Telco local loop

Always on? No Yes Allows voice at same time over same medium?

No Yes

Asymmetric? (Faster downlink possible?)

No Yes

A i t l lif d li k d 56 Kb 24 Mb

Table 9-2Internet Access Link Comparison Points: Analog and DSL29

Approximate real-life downlink speeds 56 Kbps 24 Mbps


C bl TV d bl d C bl dCable TV and cable modem: Cable modem uses different frequency channels than those used for video (TV)( )

Cable Internet service just like another TV channelanother TV channel

Instead of video, channel sends data

Figure 9-22Cable Internet Using Multiple Frequencies over a Single Circuit on Co-axial Cable30


C bl d l C bl d f d fCable modem example: Cable modem feed comes from same cable as TV connection

Figure 9-23Home Cabling and Devices for Cable Internet31


Fib t th N i hb h d (FTTN) Fib t f tFiber to the Neighborhood (FTTN): Fiber goes to front of neighborhood with coaxial rest of way to houses

Fiber to the Curb (FTTC): Fiber goes intoFiber to the Curb (FTTC): Fiber goes into neighborhood and is buried at curb (closer to homes)

Figure 9-24Hybrid Fiber Coax (HFC) and Fiber-to-the-Curb (FTTC)32


H d E d CATV ( bl TV) ’Head End: CATV (cable access TV) company’s equivalent of Telco’s Central Office (CO)

Has space to hold various devices including those thatHas space to hold various devices, including those that connect to ends of HFC cables

Figure 9-25CMTS and Head End Multiplexes Video and Data 33


Diff d i il iti b t bl I t tDifferences and similarities between cable Internet, DSL, analog modems

Name Analog Circ it DSL CableName Analog Circuit DSL CablePhysical link Telco local loop Telco local loop CATV cable Always on? No Yes Yes yAllows voice at same time over same medium?

No Yes Yes

Asymmetric? (FasterAsymmetric? (Faster downlink possible?)

No Yes Yes

Approximate real-life do nlink speeds

56 Kbps 24 Mbps 50 Mbps

Table 9-3Internet Access Link Comparison Points34

downlink speeds


Wi l T l d 4G Wi l WAN t h lWireless Telco and 4G: Wireless WAN technology supports many devices (mobile phones, tablets, laptops or other computers)p )Devices can have built-in wireless WAN card or can use wireless WAN expansion card

Figure 9-26Wireless WAN Examples35


C I t t t h l i bliConsumer Internet-access technologies use cabling already in most homes; makes it inexpensive and affordable

Figure 9-27Enterprise WAN Options Used as Internet Access Technologies36

Short Break

Take 10

37

Network Layer Concepts Before Scarce IPNetwork Layer Concepts Before Scarce IP Addresses

I di id l IP dd t b i t h h tIndividual IP addresses must be unique to each host connected to Internet before they can send or receive IP packetsp

Hosts use IP addresses based on class A, B, or C networks

Addresses can not be assigned randomly

Organized IP addresses helps routers to build usable routing tables of networks

Makes routing tables shorter and routing more efficient

38


M diff t i ti (t i ll t f tMany different organizations (typically part of some not-for-profit organization) work together to assign IP addresses for Internet worldwide

IANA: Part of ICANN (Internet Corporation for Assigned Names and Numbers) works with five worldwide regional organizations to manage address assignment processg g p

Name Locations ServedAfriNIC Africa APNIC Asia Pacific ARIN North America LACNIC Latin America, Caribbean

Table 9-4Regional Internet Registries (RIRs)39

,RIPE NCC Europe, Middle East, Central Asia


E l d f I t t O i i l l f i iEarly days of Internet: Original rule for assigning addresses was for each company to use one classful IP network for its network

When company wanted to connect to Internet, it applied to IANA for classful networkto IANA for classful network

IANA reviewed application and assigned

t k IDnetwork ID

Figure 9-29IANA Assigned Classful IP Network Numbers40


IANA IP t k i t f ll d th lIANA IP network assignments followed these general rules:1. Only assign network IDs not yet y g y

assigned to any other enterprise2. Assign class of network just large

enough to meet need of enterpriseg p

At end of process, each enterprise had public address th t f ll i t l A B Cthat fell into class A, B, or C

IP address from public network could be used to send packets to any other network in Internet

Figure 9-30Enterprises Subnet their One Classful IP Network41


E l f SOHO dd i t i l dExample of SOHO address assignment in early days: ISP1 reserved class C network 200.2.2.0

When PC2 and PC3 connect to ISP, they are given addresses , y gby ISP1 router

Figure 9-31Assigning IP Addresses to SOHO PCs42


B d G t P t l (BGP) I t t IP tiBorder Gateway Protocol (BGP): Internet IP routing protocol

Prefers routes through lessPrefers routes through less expensive links

Creates large routing tables

Figure 9-32BGP: Choosing Routes (Indirectly) Based on Business Rules 43


In Internet core, routing tables have grown to over 400,000 routes

S BGP b ilt t b b tt bl t h dl lSo BGP built to be better able to handle larger numbers of routes

Figure 9-33Scale of Internet Routing Tables: Large Enterprise Vs. Internet Core Routers 44


O l f l t kOnce classful network has been assigned to company, all routers in p y,Internet core need to know how to forward packets so they canpackets so they can reach ISP connected to company

Figure 9-34Internet Routing: IP Routes to Each Classful IP Network45


R t i k t d th d th t tRouters receive packets and then send them to next router

Figure 9-35IP Forwarding (Routing) on Several ISP Routers 46


Si l h d ti th t t i hSingle-homed connection means that enterprise has only one WAN link connecting to ISP

Figure 9-36Single-Homed Connection with Default Route 47


D l h d I t t ti t i hDual-homed Internet connection means enterprise has two (or more) connections to Internet

Gives enterprise choice ofGives enterprise choice of where to send Internet packets

Default route might not work well in suchnetwork designsnetwork designs

Figure 9-37Inefficient Routes With Dual-homed Internet Connections 48


D l h d l E t i BGP b tDual-homed example: Enterprise uses BGP between itself and both ISP1 and ISP2

ISP2’s router wouldISP2 s router would advertise routes for networks 22.0.0.0 and 23.0.0.0, and routers R1 and R2 view route to Internet through ISP2 gas better route

Figure 9-38Partial BGP Updates 49


E l U d i t t I t t ith tExample: User device connects to Internet without using router

Host has OS that includes TCP/IP softwareHost has OS that includes TCP/IP software

IP software includes concept of default router

When connectedWhen connected to Internet, host’s default router setting refers to ISP router

Figure 9-39Default Routers and Default Routes 50


N l ti d Gl b l DNS t C tiName resolution and Global DNS system: Creating globally unique hostnames

DNS names assigned by IANADNS names assigned by IANA

Process for how companies andcompanies and individuals get and use hostnames in Internet similar to assigning IP addressessimilar to assigning IP addresses

Figure 9-40Review: IANA Assigns IP Networks 51


T t l b ll i h t liTo create globally unique hostnames, process relies on domain namesWith this format names exist asWith this format, names exist as characters with periods in between

Subdomain: Last part of nameSubdomain: Last part of name

Figure 9-41Format and Examples Using Domain Names 52


T i h t th h t I t tTo ensure unique hostnames throughout Internet, company or individual must register subdomains with IANA-authorized companyp y

If requested name not already in use, agency registers name so no other entitycan use it

Figure 9-42IANA/Others Approve Subdomain Registrations 53


H t LAN f ll d i f t tHostnames on LANs follow domain name format, too

Administrative process ensures no two hostnames will ever be sameever be same

Enterprises must not duplicate namesnot duplicate names inside company

Figure 9-43IANA/Others Approve Subdomain Registrations 54

Network Layer Concepts Before Scarce IPNetwork Layer Concepts Before Scarce IP AddressesE l N f i E t 1 E t 2 dExample: Name server for companies Ent-1, Ent-2, and Ent-3

In each case name serverIn each case, name server lists short version of name, along with IP address used byIP address used by that host

Name server considers each short name toeach short name to have correct subdomain at end of name

Figure 9-44DNS Servers and Distributed Server Configurations 55


DNS d fi h ld t di t ib t d d t b fDNS defines how world creates distributed database of hostnames and their addresses

DNS server for each subdomain knows all hostnames and IP addresses for that subdomainRoot DNS servers: SpecialRoot DNS servers: Special DNS servers inside Internet know IP addresses of all DNS serversDNS defines protocol that servers use to ask among all DNS servers to find DNS server for right subdomain

Figure 9-45Finding the Right DNS Server for a Domain Name in Another Company 56


At thi i t li t d t t k t 1 ’At this point, client does not yet know www.ent-1.com’s IP address

Step 5: Server 128 1 9 9 sends nameStep 5: Server 128.1.9.9 sends name resolution request to DNS for subdomain server ent-1.comStep 6: DNS server ent 1 comStep 6: DNS server ent-1.com knows name “www.ent-1.com,” so replies with IP address 1.1.1.1Step 7: DNS server replies to ClientStep 7: DNS server replies to ClientA with IP address of 1.1.1.1 so Clientcan now send packet with correct IPaddress on itaddress on it

Figure 9-46Getting a Response from the Authoritative DNS Server for Ent-1.com 57

Network Layer Concepts with Scarce IPv4Network Layer Concepts with Scarce IPv4 Addresses

IP 4 dd h tiIPv4 address exhaustionBecame clear by late 1980s that world would run out of IPv4 addresses with current IP class planaddresses with current IP class plan

Original address assignment plan had problems in part because of sizes of classful IP networks and number of each that existed

ClassNumber of Networks

Size (Number of Host Addresses)

24A 126 224 – 2 (>16,000,000) B 16,384 216 – 2 (>65,000) C 2,097,192 28 – 2 (254)

Table 9-4Number and Sizes of Classful IP Networks58


E l f IP dd i t E t i k fExample of IP address assignment: Enterprise asks for Class B network from IANA

IANA grants networkIANA grants network 128.1.0.0

Internet routers d t tiupdate routing

tables with routes for 128.1.0.0; entire class B networkentire class B network must be in one place

Figure 9-47Wasted IP Addresses: Got 65,000, Need 50059


G h N b f ti t dGraph: Number of estimated Internet hosts 1984 – 1992

Data derived primarily from RFCData derived primarily from RFC 1296, which collected growth data in part because of IP address exhaustion problem

Figure 9-48Approximate Number of Hosts Connected to the Internet, 1984 - 199260


Cl l I t d i R ti (CIDR) O th d tClassless Interdomain Routing (CIDR): One method to deal with IP address depletion

Used by IANAUsed by IANA

Each CIDR block is set of consecutive IPconsecutive IP addresses unique in Internet (same as classful IP networks)classful IP networks)

Figure 9-49IANA Assigns to ISP; ISP Assigns Smaller CIDR Block to Customer61


CIDR d ti t bl th ith tCIDR reduces routing table growth with route aggregation

Example: ISP1 has 3 customers each of which has CIDR blockExample: ISP1 has 3 customers, each of which has CIDR block of public IP addresses

Router R4 (part f ISP1’of ISP1’s

network) has routes for each customer’s CIDRcustomer s CIDR block

Figure 9-50CIDR Address Assignment Creates Larger Routing Tables62


R t ti i ld id IP ddRoute aggregation requires worldwide IP address assignment process to assign numbers in large, consecutive groupsg p

Large group first assigned to large enterprise such as ISPas ISP

Then ISP assigns smaller CIDR blocks to its customers

Administrative process allows routers to create aggregate routes for original large blocks, rather than separate routes for each individual smaller block

Figure 9-51CIDR Route Aggregation Keeps Other ISP Routing Tables Smaller63


N t k Add T l ti (NAT) W t t l tNetwork Address Translation (NAT): Way to translate multiple PRIVATE addresses to single PUBLIC address for Internet access

Figure 9-52Hosts with Public IP Addresses Connected to Servers in the Internet64


Th diff t ti f h tThree different connections from one hostServer maps IP address for each connection

Figure 9-53One Client Host with Three Application Connections65


NAT bi ti i tNAT combines connections into oneExample: Three real devices each connect to same real web serverRouter implementing NAT makes all three connections look like they come from single host (128.1.1.4)

Figure 9-54NAT Function on a Router66


E l i i t d bli IP ddExample using private and public IP addresses Three separate enterprises use PRIVATE networks based on 10.0.0.010.0.0.0

Each company uses different PUBLIC IP address block to access Internetto access Internet

Figure 9-55Three Enterprises Networks, Each Using Private Network 10.0.0.067


P bli d i t IP dd RFC 1918 t idPublic and private IP addresses: RFC 1918 sets aside several private IP network address blocks

Enterprise can pick private address block assign IPEnterprise can pick private address block, assign IP addresses from that block, subnet that block, etc.

ClassNumber of Networks

Network IDs

A 1 10.0.0.0 B 16 172.16.0.0 - 172.31.0.0

C 256 All that begin 192.168 (192.168.0.0, 192.168.1.0, 192.168.2.0, and so on, through 192.168.255.0)

Table 9-5Private IP Networks68

9 . 68. .0, a d so o , t oug 9 . 68. 55.0)


B i NAT h i NAT t l t ( h ) IPBasic NAT mechanics: NAT translates (changes) IP addresses inside IP headers as packets pass through device doing NATg

Step 1: PC sends packet to router

Steps 2-3: Router translates private IP to public IP

Step 4: Router sends updated packet to public Internet

Figure 9-56NAT Translating the Source Address in Packet from Inside to Outside69


NAT example Part 2: Server replies to hostNAT example, Part 2: Server replies to hostPacket comes into NAT router with IP address of 200.1.1.1

Step 6: RouterStep 6: Router consults its NAT table to translate packet’s addresspto Client A’s IP address (10.1.1.1)

Step 7: RouterStep 7: Router forwards packet to Client A

Figure 9-57NAT Translating the Destination Address in Packet from Outside to Inside70


E t i till d bli IP ddEnterprise still needs some public IP addresses so can access Internet and be accessible by users outside enterprise (e.g., for web services)p ( g , )1. For NAT devices

2. For hosts in enterprise that need static, public IP addresses (typically servers)

Figure 9-58Public and Private IP Addresses in the Enterprise71


SOHO dd i t M t SOHO ti tSOHO address assignment: Most SOHO connections to Internet use small, consumer-grade routers that typically combine many yp y yfunctions into one device

Figure 9-59Various Roles of Consumer “Router”72


R t t i ll h d f lt hRouter typically has defaults such asDynamically uses one public IP address (from ISP) on WAN portUses that one public IP for NATMakes WAN port “outside” port for NATProcesses traffic coming in from LAN ports with NATProcesses traffic coming in from LAN ports with NATPicks one private IP network to use on LAN (typically 192.168.1.0)Acts as DHCP server on LAN ports to lease IP addresses to allActs as DHCP server on LAN ports to lease IP addresses to all hosts on LANActs as firewall, allowing Intranet clients to connect to Internet and preventing Internet clients from getting onto Intranetand preventing Internet clients from getting onto Intranet

Figure 9-59Various Roles of Consumer “Router”73


E l SOHO dd i tExample SOHO address assignment

User can change router defaults or use directly out of boxor use directly out of box as is

Figure 9-60Default Settings on a Consumer-Grade Integrated Router74

Summary - This Chapter…Explained how individual devices some home-basedExplained how individual devices, some home based TCP/IP networks, corporate TCP/IP networks, and ISP TCP/IP networks connect to create the global Internet.

Showed the typical devices and connections used in a connection from a corporate TCP/IP network and an ISPISP.

Described how ISPs work together to create the Internet core.

Generally described the layer 1 and 2 features used when connecting to an ISP using analog modems, DSL modems, and cable modems.

75

Summary - This Chapter…Compared and contrasted analog modems DSL andCompared and contrasted analog modems, DSL, and cable as Internet access technologies.

Explained IP routing in the Internet, in the direction p g ,from Enterprise towards the Internet and from the Internet towards an Enterprise.

Listed the typical steps that occur when a client needs to do name resolution for a hostname that exists in a different DNS subdomain.

Compared and contrasted the public IP address assignment process that was used before IP address exhaustion, and after the introduction of CIDR.

76

Summary - This Chapter…Explained the basic reasons why CIDR needed a routeExplained the basic reasons why CIDR needed a route aggregation feature, and how route aggregation helped fill that need.

Explained the fundamental concepts behind how NAT reduces the number of required public IP addresses.

77

Questions? Comments?

78

Documents

NT1210 Introduction to Networking - YPW · The Internet as a Network of Networks SiIt td Et iSecuring Internet edge: Enterprises use many security measures and devices to make Internet