Datacommunication. Internet Infrastructure IPv4 & IPv6

(1)

D C I P Slide 1

Datacommunication

Internet Infrastructure

IPv4 & IPv6

Eric Malmström

[email protected]

D C I P

Background

• mid 1970 DARPA finances research on packet

switching networks

• p-p networks, packet radio and satellite comm. • implementation of TCP/IP in Arpanet 1980-1983 • Internet = Arpanet + Milnet

(2)

D C I P Slide 3

Internet organisation

• IAB - Internet Architecture Board • IETF - Internet Engineering Task Force • ISOC - Internet Society

• IANA - Internet Assigned Numbers Authority • Standardisation through

RFC - Request For Comment All standards are RFCs Not all RFCs are standards

• Coordination with ISO

TCP/IP (Internet) services

• Network layer services

– connectionless packet forwarding – independent of network technology – universal connectivity

• Transport layer services

– connection oriented "reliable transport service" – end-to-end handshaking • Application services – electronic mail – file transfer – terminal access – informations services

• Weight more and more on applications

(3)

D C I P Slide 5

Overview TCP/IP protocols

Simplified overview

V.24 Ethernet Token_Ring

Physical Data Link Network Transport Session Presentation Application IP and ICMP Telnet FTP SMTP TCP UDP TFTP NFS SNMP V.35 FDDI X.25 HDLC WWW D C I P

IPv4 - I

nternet

P

rotocol

IPv4 - I

nternet

P

rotocol

• Logical addressing for routing at network layer • Network routing through 32-bit logical address

(IP-address) containing network address and host address

• Only error control is checksum

• IP hides differences between different media

from higher layer protocols

• Fragmentation of datagrams ( when two

(4)

D C I P Slide 7

IPv4 datagram

Vers IHL Service Type Total length

Identification Flags Fragment Offset

Time To Live Protocol Header Checksum

Source IP Address Destination IP Address IP options (if any)

DATA . . .

Padding 0 4 8 16 19 24 31

VERS: IP protocol version (=4) IHL: Header Length IDENT: Identifies fragments of the same datagram

FLAGS: DF MF DF: Don´t Fragment MF: More Fragments

IP-address

• IP-address is 32 bits, i.e. 4 bytes

• Global hierarchical address coordination

– IANA -> RIPE -> Local-IR for addresses in Sweden

• IP-address 32 bits can de divided in several

ways between network and host address

(5)

D C I P Slide 9

Multicast

• applications -

one- to-many, many-to-many

– video conference – ”resource discovery” – stock exchange information – ....

• uses Class D addresses

224.0.0.0 - 239.255.255.255 1 1 10 Multicast address D C I P

Subnetting

• Subnetting: a method for an organisation to

divide its IP-network into several

administratively separated subnetworks

• Host part of address partitioned in subnet

address and host address

AA BB CC DD

Host

Network Subnet

(6)

D C I P Slide 11

Subnet mask

• Border between subnet and host defined by

subnet mask. Border can be chosen freely.

Host Network Subnet 1 1 1 1 1 1 1 1.1 1 1 1 1 1 1 1.1 1 1 1 1 1 1 1.0 0 0 0 0 0 0 0 Subnet mask 255.255.255.0 or /24 Host Network Subnet 1 1 1 1 1 1 1 1.1 1 1 1 1 1 1 1.1 1 1 1 1 1 1 1.1 1 0 0 0 0 0 0 Subnet mask 255.255.255.192 or /26

Subnet mask example

(7)

D C I P Slide 13

Variable Length Subnet Mask

Router Router Subnet 185.150.1.0 Mask 255.255.255.0 Subnet 185.150.15.16 Mask 255.255.255.252 Outside world Subnet 185.150.2.0 Mask 255.255.255.0 address 185.150.15.17

Mask 255.255.255.252 address 185.150.15.18Mask 255.255.255.252

Subnet 185.150.0.0 Mask 255.255.240.0

Routing protocol must transfer mask information (not only network number) and aggregate subnets

D C I P

Problems with IP-addresses

Three main problems:

• would have run out of B-addresses by start of

1995 if nothing done

• if C-addresses allocated instead, routing tables

in Internet backbone routers will overflow

• in the long term we will run out of IP-addresses

Solutions

• CIDR, Classless Inter-Domain Routing

• Geographical allocation of network addresses • Stricter rules to get a network address

(8)

D C I P Slide 15

CIDR - Classless Interdomain Routing

Internet

Swedish Internet operator

Company A Organisation B Company X

194.65.128.0 194.65.131.0 _194.65.132.0 194.65.192.0 194.65.255.0 194.65.128.0/17 194.65.128.0/22 _{194.65.132.0/24} 194.65.192.0/18

Firewalls

• packet filters • application gateway

• network address translator (NAT)

• adds security

(9)

D C I P Slide 17

”Private address space”

• Addresses reserved for company internal

networks (Private internets)

• These networks will not be routed in the

Internet 10.0.0.0 - 10.255.255.255 172.16.0.0 - 172.31.255.255 192.168.0.0 - 192.168.255.255 D C I P

IPv6

Design goals

• support billions of hosts • reduce size of routing tables • simplify header: routers process

packets faster • better security

• allow future protocol evolution • Type Of Service (support for

real-time data) • aid multicasting

• permit old and new protocol co-existence

• allow host to roam without changing address

Goal met

• 16 byte address

• address space handling • 7 fields in header and

extension headers

• authentication and privacy • extension headers

• flows, priority • scope, group type

(10)

D C I P Slide 19

IPv6 Header

Version=6 Prio: 0-7 flow controllable, 8-15 constant send rate Flow label: traffic flow as vitual circuit

Next header: IP extension header or layer 4 protocol

Version Priority Flow label

Payload length Next header Hop limit

Source Address (16 bytes)

Destination Address (16 bytes)

0 4 8 16 24 31

Comparison IPv4 <-> IPv6

Version Priority Flow label

Payload length Next header Hop limit

Source Address (16 bytes)

Destination Address (16 bytes)

0 31

Vers IHL Service Type Total length

Identification Flags Fragment Offset

Time To Live Protocol Header Checksum

Source IP Address (4 bytes) Destination IP Address (4 bytes)

IP options (if any) Padding

(11)

D C I P Slide 21

Packet sizes and fragmentation

• Minimum link MTU = 576 bytes

• Expectation: end systems perform MTU

discovery

• Fragmentation generally discouraged • Routers do not fragment en-route packets • Maximum packet payload 65536 bytes (16 bit

field)

• Provision for ”jumbograms” (hop-by-hop

option)

D C I P

IPv6 addresses

Prefix (byte 1) Usage

0000 0000 Reserved

incl IPv4

0000 0001 unassigned

0000 001 OSI NSAP addr.

0000 010 Novell IPX addr.

0000 011 unassigned 0000 1 unassigned 0001 unassigned 001 unassigned 010 Provider-based addresses 011 unassigned Prefix Usage 100 Geographic-based addresses 101 unassigned 110 unassigned 1110 unassigned 1111 0 unassigned 1111 10 unassigned 1111 110 unassigned 1111 1110 0 unassigned

1111 1110 10 Link local use addr. 1111 1110 11 Site local use addr.

1111 1111 Multicast

(12)

D C I P Slide 23

IPv6 - router packet handling

Routers process packets faster

• fewer fields in header

• reduction of routing table size • no IP checksum calculation

• introduction of Flow concept (similar to VC) • better support for options, easier for routers

to skip non-relevant options

IPv6 - Extensions

Optional ”linked list” of Extension headers

• Hop-by-hop options (info for routers)

– e.g. jumbogram

• Routing (route to follow)

– strict or loose

• Fragmentation (hosts only) • Authentication (for receiver)

(13)

D C I P Slide 25

IPv6 - Multicast

Address prefix 1111 1111 followed by

• 4-bit Flag field

– permanent or transient multicast group

• 4-bit Scope field

– link, site, organisation, planet, ...

• 112-bit (14 byte) group identifier

D C I P

ICMP - I

nternet

C

ontrol

M

essage

P

rotocol

ICMP - I

nternet

C

ontrol

M

essage

P

rotocol

• protocol for error reporting IP-to-IP • reports errors back to source/sender

• Test reachability Echo Request, Echo Reply

• Non-deliverable datagram Destination Unreachable

• Flow control Source Quench

• Change routing Redirect

• Ask for subnet mask Address Mask Request & Reply

(14)

D C I P Slide 27

Ex: Traceroute www.ntt.co.jp

traceroute to www.ntt.co.jp (210.173.163.201), 30 hops max, 40 byte packets 1 v1-car-sto-e3.global-ip.net (194.52.237.241) 4 ms 2 ms 3 ms 2 v100-bar-sto-fe0-1-0.global-ip.net (194.52.1.55) 3 ms 2 ms 3 ms 3 gip-stkh-bar-2-fe1-0-0.gip.net (195.17.9.244) 3 ms 2 ms 3 ms 4 gip-arch-3-atm5-0-0-744-aal5.gip.net (204.59.5.101) 60 ms 58 ms 60 ms 5 gip-penn-6-pos1-0.gip.net (204.59.138.21) 128 ms 127 ms 128 ms 6 gip-penn-2-pos8-0-0.gip.net (204.59.138.14) 128 ms 128 ms 128 ms 7 sprint-nap.iij.net (192.157.69.65) 148 ms 149 ms 145 ms 8 216.98.96.249 (216.98.96.249) 150 ms 150 ms 153 ms 9 Osaka-ibb0.IIJ.Net (202.232.0.225) 327 ms 325 ms 309 ms 10 202.232.0.145 (202.232.0.145) 338 ms 322 ms 315 ms 11 202.232.3.186 (202.232.3.186) 335 ms 319 ms * 12 mfeedgw.iij.net (202.232.9.34) 337 ms 337 ms 382 ms 13 IIJ-a-gate.mfeed.net (210.173.161.73) 318 ms 337 ms 338 ms 14 * * * 15 * * * >

ARP - A

ddress

R

esolution

P

rotocol

ARP - A

ddress

R

esolution

P

rotocol

• ARP maps logical IP-address (network

address) to physical Ethernet address.

• ARP sends BROADCAST containing

IP-address.

(Who has IP-address xyz?)

• Host with IP-address xyz answers with its

physical Ethernet address.

• Hosts build table of IP - Ethernet address

(15)

D C I P Slide 29

RARP - R

everse

ARP

RARP - R

everse

ARP

• RARP uses physical Ethernet address to find

logical IP-address

• Used for example for nework loading of

diskless workstations

• work station and RARP-server must be on the

same network

• ARP and RARP are link layer frame types

D C I P

DNS - Domain Name Service

• hierarchical domain-based naming structure • distributed database system

• maps names to information

– IP-address – mail host – ...

• enables name-based addressing

(ASCII strings instead of binary addresses) Function:

application resolver name server(s)

(name) (info)

(16)

D C I P Slide 31

DNS Name Space

us nu ... se edu com gov mil net

globalone volvo ericsson uu

adb docs udac

hosts hosts hosts hosts (unnamed root) countries generic

• name space divided into Zones

• each zone has Name servers, one primary and

one or several secondaries

Name server & resolver

Resolver Name Server Name Server Name Server

(name) (info) (name) (info) (name) (info)

Resolver Name Server

(17)

D C I P Slide 33

DNS - example

Router DNS

Name server Outside world

(1) http://www.ftg.se (2)" What is www.ftg.se ? IP-address of (3) "www.ftg.se has address 185.150.23.4" (4) http 185.150.23.4 D C I P

DNS resource records

Main DNS resource record types

Type Meaning Value

SOA Start Of Authority Parameters for zone A IP Address of host IP-address

MX Mail eXchange Prio, mail accepting host NS Name Server Name server for domain CNAME Canonical Name Alias name

PTR Pointer Alias for IP-address

HINFO Host info CPU and OS in ASCII

(18)

D C I P Slide 35

DNS and e-mail

Router DNS

Name server Outside world

(1) mail [email protected] (2)" What is MX-data

for xyz.se?" (3) "xyz.se has MX- address mail.xyz.se and is reached with SMTP"

(4) smtp 185.150.23.34

PPP - P

oint to

P

oint

P

rotocol

PPP - P

oint to

P

oint

P

rotocol

• standard for communication over serial lines

(point-to-point)

• used e.g. between routers from different

vendors

• transmits layer 3 protocol data and

transparent bridging over WAN-link

• PPP has 16-bit protocol identifier

(19)

D C I P Slide 37

Host configuration

Router