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11-01-K.Steenhaut & J.Tiberghien - VUB1
TelecommunicationsConcepts
Chapter 4.2
IPv4 and
Other Networks
11-01-K.Steenhaut & J.Tiberghien - VUB2
Contents• Transmitting IP datagrams
• IP over Local Area Networks• IP over Wide Area Networks
– IP over leased lines– IP over circuit switched networks– IP over packet switched networks
» IP over X25» IP over Frame Relay» IP over ATM» IP and Quality of Service
– MPLS• Conclusions
11-01-K.Steenhaut & J.Tiberghien - VUB3
Contents• Transmitting IP datagrams
• IP over Local Area Networks• IP over Wide Area Networks
– IP over leased lines– IP over circuit switched networks– IP over packet switched networks
» IP over X25» IP over Frame Relay» IP over ATM» IP and Quality of Service
– MPLS• Conclusions
11-01-K.Steenhaut & J.Tiberghien - VUB4
The Internet Sublayer
IP approachApplication 1 Application 2 Application 3
TCP
Internet Protocolan
yn
etw
ork
UDP
11-01-K.Steenhaut & J.Tiberghien - VUB5
Transmitting IP Datagrams
IProuter
IP router
UnderlyingNetwork
UnderlyingNetwork
IP Datagram
Underlying Network Frame
11-01-K.Steenhaut & J.Tiberghien - VUB6
Contents• Transmitting IP datagrams
• IP over Local Area Networks• IP over Wide Area Networks
– IP over leased lines– IP over circuit switched networks– IP over packet switched networks
» IP over X25» IP over Frame Relay» IP over ATM» IP and Quality of Service
– MPLS• Conclusions
11-01-K.Steenhaut & J.Tiberghien - VUB7
IP over Ethernet
Application 1 Application 2 Application 3
TCP
Internet Protocol
Ethernet
UDP
11-01-K.Steenhaut & J.Tiberghien - VUB8
Address Resolution Protocol
• Problem :– Mapping of IP and Ethernet addresses
• Solution :– ARP entity broadcasts IP address over
Ethernet
– All hosts compare broadcasted IP address with their own (software defined) IP address
– Identified host answers the ARP broadcast.
– IP datagrams for resolved address are encapsulated in Ethernet frame with Ethernet destination address.
11-01-K.Steenhaut & J.Tiberghien - VUB9
IP over IEEE 802 LANs
4
3
2b
4
3
2b
1 1
IP addresses need to be translated into LAN addresses
2a 2a
802.2 cls
11-01-K.Steenhaut & J.Tiberghien - VUB10
IP over traditional LANs
4
3
4
3
1 1
IP addresses need to be translated into LAN addresses
2a 2a
11-01-K.Steenhaut & J.Tiberghien - VUB11
ReverseAddress Resolution
Protocol• Problem :
– Diskless workstations can not keep their (software defined) IP address.
• Solution :– A configuration server keeps mapping between IP
addresses and corresponding Ethernet addresses.
– At boot time a diskless station broadcasts a RARP frame.
– Configuration server reads source Ethernet address in RARP frame and answers with corresponding IP address.
11-01-K.Steenhaut & J.Tiberghien - VUB12
Contents• Transmitting IP datagrams
• IP over Local Area Networks• IP over Wide Area Networks
– IP over leased lines– IP over circuit switched networks– IP over packet switched networks
» IP over X25» IP over Frame Relay» IP over ATM» IP and Quality of Service
– MPLS• Conclusions
11-01-K.Steenhaut & J.Tiberghien - VUB13
Directly linked Routers
11-01-K.Steenhaut & J.Tiberghien - VUB14
General Purpose SDH Networks
PABXPABX
11-01-K.Steenhaut & J.Tiberghien - VUB15
Contents• Transmitting IP datagrams
• IP over Local Area Networks• IP over Wide Area Networks
– IP over leased lines– IP over circuit switched networks– IP over packet switched networks
» IP over X25» IP over Frame Relay» IP over ATM» IP and Quality of Service
– MPLS• Conclusions
11-01-K.Steenhaut & J.Tiberghien - VUB16
IP Networks
Router1.2
1.4
1.3 1.1
2.1
3.3
3.24.1
4.3
4.2
5.2
2.2
2.3
6.1
6.2
5.35.1
7.17.2
6.3
11-01-K.Steenhaut & J.Tiberghien - VUB17
Serial Line Internet Protocol
• Designed in 1984 by Rick Adams (RFC 1055)
• For temporary IP links
• Data Link :
– IP datagrams encapsulated in SLIP frames
– Frame delimited by unique character (11000000)
– Character stuffing within the frame
– No error detection (nor correction !)
• Network Layer : no layer 3 functions
• Many slightly different versions (RFC 1144)
• Essentially obsolete !
11-01-K.Steenhaut & J.Tiberghien - VUB18
Point to Point Protocol
• Designed by the IETF (RFC 1661,RFC 1662,RFC 1663)
• For temporary links (various network protocols)
• Data Link : similar to HDLC or 802.2, but with bytes
– Payload encapsulated in P frames
– Frame delimited by 802.2 flag (01111110)
– Character stuffing within the frame
– Optional error correction with sliding window
• Network Layer : support for different protocols
– Connection management, with authentication
– Network protocol identifier field
11-01-K.Steenhaut & J.Tiberghien - VUB19
Point to Point Protocol
• Multiple protocols over PPP
• Various physical layers under PPP
TCP
IP
PPP
UDP
IPX?
Application,Transport &Network layers
Physical layer
PS
TN
ISD
N
GS
M
Lea
sed
Lin
es
AD
SL
?
11-01-K.Steenhaut & J.Tiberghien - VUB20
P P P Advantages over
SLIP
• CRC on every frame for error detection
• A link control protocol to:
– establish connection
– negotiate options
– close connection
• Specific network control protocols
– e.g. dynamic IP address assignment
– e.g. TCP/IP header compression
11-01-K.Steenhaut & J.Tiberghien - VUB21
IP over ISDN
• Usage :– Temporary interconnections
– Back-up for leased lines
– Additional capacity for overloaded leased lines
• Main problem :IP : Connectionless >< ISDN : Connection oriented
• Solutions :– One call per datagram (fast connection)
– Keep connection for entire billing units
– Keep connection during work-hours
11-01-K.Steenhaut & J.Tiberghien - VUB22
Contents• Transmitting IP datagrams
• IP over Local Area Networks• IP over Wide Area Networks
– IP over leased lines– IP over circuit switched networks– IP over packet switched networks
» IP over X25» IP over Frame Relay» IP over ATM» IP and Quality of Service
– MPLS• Conclusions
11-01-K.Steenhaut & J.Tiberghien - VUB23
IP over X25
4
3
4
3
1 1
2 2
X25
IP datagramVCNX25 overhead
IP addresses need to be translated into X25 addresses
3 3
11-01-K.Steenhaut & J.Tiberghien - VUB24
IP over X25
• Fast select call : best match between IP and X25
• Virtual circuit between source and destination routers
– Switched : opened and closed when ?
– Permanent : analog to leased line, preferred solution
• Address resolution :
IP address need to be translated into
– X25 address for fast select call or for opening circuit
– VC number for forwarding packet(s)
11-01-K.Steenhaut & J.Tiberghien - VUB25
Contents• Transmitting IP datagrams
• IP over Local Area Networks• IP over Wide Area Networks
– IP over leased lines– IP over circuit switched networks– IP over packet switched networks
» IP over X25» IP over Frame Relay» IP over ATM» IP and Quality of Service
– MPLS• Conclusions
11-01-K.Steenhaut & J.Tiberghien - VUB26
IP over Frame Relay
4
3
2
4
3
2
1 1
FR
IP datagramVCNFR overhead
IP addresses need to be translated into PVC numbers
11-01-K.Steenhaut & J.Tiberghien - VUB27
IP over Frame Relay
• IP addresses need to be translated into Permanent
Virtual Circuit Numbers.
• Assigning different application flows to PVC’s with
different CIRs can enforce QOS criteria
• Passing the Congestion Notification bits to the
transport layer could be useful but requires special IP
and TCP/UDP implementations
11-01-K.Steenhaut & J.Tiberghien - VUB28
Contents• Transmitting IP datagrams
• IP over Local Area Networks• IP over Wide Area Networks
– IP over leased lines– IP over circuit switched networks– IP over packet switched networks
» IP over X25» IP over Frame Relay» IP over ATM» IP and Quality of Service
– MPLS• Conclusions
11-01-K.Steenhaut & J.Tiberghien - VUB29
IP over ATM
Ap
plic
ati
on
1
Ap
plic
ati
on
2
Ap
plic
ati
on
3
TCP-UDP
IP
any
net
wo
rk
Ap
plic
ati
on
1
Ap
plic
ati
on
2
Ap
plic
ati
on
3
AT
M
aal
AT
Maal
11-01-K.Steenhaut & J.Tiberghien - VUB30
IP over ATM, but...
• IP is connectionless, – each packet contains destination and origin
addresses.– Broadcasting of messages frequently required
• ATM is connection oriented,– Virtual channels need to be established (and
evt. closed)– each cell contains a Virtual Channel number– ATM addresses are unrelated to IP addresses– No broadcasting
• Connection management required.• Address Translation mechanism required.• Broadcast server required
11-01-K.Steenhaut & J.Tiberghien - VUB31
IP over ATM
4
3
4
3
1 1ATM
IP datagramvcnATM/AAL overhead
AAL
11-01-K.Steenhaut & J.Tiberghien - VUB32
ATM Adaptation Layer
Data encapsulation
pad AAL
pad AAL
Higher layer PDU
ATM header
11-01-K.Steenhaut & J.Tiberghien - VUB33
IP over ATM, solutions
1 . Classical IP over ATM– Initially proposed by IETF
– ARP server translates the addresses
– All addresses stored on one ARP server define one subnet
– Different subnets have to communicate via routers
– Broadcasts have to be generated by IP entity
– Requires modified IP implementation
11-01-K.Steenhaut & J.Tiberghien - VUB34
Classical IP over ATM
Router ARP Server
ATM Network
11-01-K.Steenhaut & J.Tiberghien - VUB35
LAN emulation
Ap
plic
ati
on
1
Ap
plic
ati
on
2
Ap
plic
ati
on
3
TCP-UDP
IP
any
net
wo
rk
AT
MLLC
Ap
plic
ati
on
1
Ap
plic
ati
on
2
Ap
plic
ati
on
3???
???
11-01-K.Steenhaut & J.Tiberghien - VUB36
IP over ATM, solutions
2 . LAN emulation– Proposed by ATM Forum
–Ethernet MAC emulation – Two or three servers:
» Lan Emulation Server registers and translates MAC addresses
» Broadcast and Unknown Server distributes the broadcast and multicast packets
» Lan Emulation Configuration Server keeps ATM addresses of Lan Emulation Servers
– No modifications to IP
11-01-K.Steenhaut & J.Tiberghien - VUB37
LAN Emulation
Router LES,BUS,LECS Servers
ATM Network
Bridge
11-01-K.Steenhaut & J.Tiberghien - VUB38
Contents• Transmitting IP datagrams
• IP over Local Area Networks• IP over Wide Area Networks
– IP over leased lines– IP over circuit switched networks– IP over packet switched networks
» IP over X25» IP over Frame Relay» IP over ATM» IP and Quality of Service
– MPLS• Conclusions
11-01-K.Steenhaut & J.Tiberghien - VUB39
IP and QOS
• Facts :
– Connectionless IP is unable to guarantee QOS
– Multi-media applications require QOS
• Solutions :
– Provide more than enough capacity between routers
– Force, for specific flows, special routes.
– Use QOS resources of underlying network
» Traditional routing algorithms do not allow differentiation between datagrams with same destination.
» Additional intermediate protocols needed
11-01-K.Steenhaut & J.Tiberghien - VUB40
IP and QOS
• Facts :
– Connectionless IP is unable to guarantee QOS
– Multi-media applications require QOS
• Solutions :
– Provide more than enough capacity between routers
– Force, for specific flows, special routes.
– Use QOS resources of underlying network
» Traditional routing algorithms do not allow differentiation between datagrams with same destination.
» Additional intermediate protocols needed
11-01-K.Steenhaut & J.Tiberghien - VUB41
IP and QOS
• Facts :
– Connectionless IP is unable to guarantee QOS
– Multi-media applications require QOS
• Solutions :
– Provide more than enough capacity between routers
– Force, for specific flows, special routes.
– Use QOS resources of underlying network
» Traditional routing algorithms do not allow differentiation between datagrams with same destination.
» Additional intermediate protocols needed
11-01-K.Steenhaut & J.Tiberghien - VUB42
IP v4 Header (2)
Source IP Address
Destination IP Address
Options Padding
Header Checksum
Ident Frag.Offset
Total Length
TTL
Typ.Ser.
Fl.
Proto
Ver Len
Typ.Serv.: Precedence (0 = normal, 7 = control)D = Short delay wanted (best effort)T = High throughput wanted (best effort)R = High reliability wanted (best effort)
11-01-K.Steenhaut & J.Tiberghien - VUB43
IP v4 Options
Class 0 Length
Option
– 1 : End of option list 1
– 2 : Security and handling restrictions 11
– 3 : Loose Source Routing var
– 7 : Record route var
– 9 : Strict Source Routing var
Class 2
Option
– 4 : Internet timestamp var
11-01-K.Steenhaut & J.Tiberghien - VUB44
QOS Routing
Ser = D
Ser = T
Ser = R
11-01-K.Steenhaut & J.Tiberghien - VUB45
IP and QOS
• Facts :
– Connectionless IP is unable to guarantee QOS
– Multi-media applications require QOS
• Solutions :
– Provide more than enough capacity between routers
– Force, for specific flows, special routes.
– Use QOS resources of underlying network (ATM)
» Traditional routing algorithms do not allow differentiation between datagrams with same destination.
» Additional intermediate protocols needed
11-01-K.Steenhaut & J.Tiberghien - VUB46
Multi Protocol Over ATM
Single or initial frame
ATM Network
= MPOA server
11-01-K.Steenhaut & J.Tiberghien - VUB47
Multi Protocol Over ATM
Subsequent frames
ATM Network
= MPOA server
11-01-K.Steenhaut & J.Tiberghien - VUB48
Contents• Transmitting IP datagrams
• IP over Local Area Networks• IP over Wide Area Networks
– IP over leased lines– IP over circuit switched networks– IP over packet switched networks
» IP over X25» IP over Frame Relay» IP over ATM» IP and Quality of Service
– MPLS• Conclusions
11-01-K.Steenhaut & J.Tiberghien - VUB49
Multi Protocol Label Switching
= Ingres/Egres Router
Any Network
Add signaling protocol to network to allow establishment of virtual circuit for some data flows.
11-01-K.Steenhaut & J.Tiberghien - VUB50
Multi Protocol Label Switching
IP datagramlabelX25 overhead
IP datagramlabelFR overhead
IP datagramlabelATM overhead
Optimizes IP address to VC number translationby explicitly identifying flows of datagramswith common QOS requirements.MPLS = attempt to standardize these labels(RFC 3031 - Jan 2001)
11-01-K.Steenhaut & J.Tiberghien - VUB51
IP v6 Header
Source IP Address
Destination IP Address
Payload Length
Flow Label
Next Hdr Hop Lim.
Ver Pri
Flow = connection oriented communicationimplemented through connectionless service
Flow uniquely identified bysource addressflow label
Avoids label field between layer 2 and 3 overhead
Flow Label : enables MPLS in IP V6
11-01-K.Steenhaut & J.Tiberghien - VUB52
Contents• Transmitting IP datagrams
• IP over Local Area Networks• IP over Wide Area Networks
– IP over leased lines– IP over circuit switched networks– IP over packet switched networks
» IP over X25» IP over Frame Relay» IP over ATM» IP and Quality of Service
– MPLS• Conclusions
11-01-K.Steenhaut & J.Tiberghien - VUB53
The Future ???
IP
ATM
SDH
Application
IP+MPLS
ATM/FR
SDH
Application
IP+MPLS
ATM/FR
SDH
Application
IP+MPLS
ATM/FR
SDH
Application
Optical Fibers + WDM
IPv6
ATM/FR
SDH
Application
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