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![Source/Destination Port — for multiplexing
Seq — seq number of the first data byte
Ack — next seq number sender is expecting
Data offset — size of header in 32-bit words, usually 5
Flags — Flags (ACK, PSH, RST, SYN, FIN, etc…)
Window Size —size of the receive window
Checksum — TCP header, data and pseudo-header
Urgent Pointer — offset to last urgent byte
Options — usually empty
TCP Header
5
Source Port Destination Port
Sequence Number
Acknowledgement Number
Off
TCP Checksum
Data
...
[Options …]
0 32
Protected by
TCP Checksum
DataOffset
Flags Window Size
Urgent Pointer
Pseudo
header?
Examples?
Ver IHL DSCP Total LengthE
ID Fl Fragment Offset
TTL Proto = TCP IP Header Checksum
Source Address
Destination Address
[Options …]
0 32
IHL
Protected by IP
Header Checksum](https://image.slidesharecdn.com/networkingfundamentalstransportprotocolstcpandudp-180621134118/75/Networking-Fundamentals-Transport-Protocols-TCP-and-UDP-5-2048.jpg)
![TCP Connection Establishment
Server
Port: 80
Src: 1026, Dst: 80
SYN 132
1
Client
Port: 1026
Source Port Destination Port
Sequence Number
Acknowledgement Number
Off
TCP Checksum
Data
...
[Options …]
0 32
Flags: SYN ACK Window Size
Urgent Pointer
Src: 80, Dst: 1026
SYN 69, ACK 132+1
2
Src: 1026, Dst: 80
ACK 69+1
3
11](https://image.slidesharecdn.com/networkingfundamentalstransportprotocolstcpandudp-180621134118/75/Networking-Fundamentals-Transport-Protocols-TCP-and-UDP-11-2048.jpg)
![TCP Error Recovery
12
TCP Client TCP
ACK 701
Data
[ ...
HTTP
GET /
HTTP
OK
TCP
SEQ 70
...SEQ 80
… ]SEQ 90
ACK 80
...SEQ 80
2
3
4
6
TCP Server
5](https://image.slidesharecdn.com/networkingfundamentalstransportprotocolstcpandudp-180621134118/75/Networking-Fundamentals-Transport-Protocols-TCP-and-UDP-12-2048.jpg)
![TCP Connection Termination
Server
Port: 80
Src: 1026, Dst: 80
FIN 99
1
Client
Port: 1026
Source Port Destination Port
Sequence Number
Acknowledgement Number
Off
TCP Checksum
Data
...
[Options …]
0 32
Flags: FIN ACK Window Size
Urgent Pointer
Src: 1026, Dst: 80
ACK 142+1
4
Src: 80, Dst: 1026
ACK 99+1
2
Src: 80, Dst: 1026
ACK 99+1, FIN 142
3
13](https://image.slidesharecdn.com/networkingfundamentalstransportprotocolstcpandudp-180621134118/75/Networking-Fundamentals-Transport-Protocols-TCP-and-UDP-13-2048.jpg)
![Source/Destination Port — for multiplexing
Length —length of UDP header and data
Checksum — header, data and pseudo-header
UDP Header
15
Source Port Destination Port
Length
Data
...
0 32
Protected by
UDP Checksum
8B
UDP Checksum
Pseudo
header?
Ver IHL DSCP Total LengthE
ID Fl Fragment Offset
TTL Proto = UDP IP Header Checksum
Source Address
Destination Address
[Options …]
0 32
IHL
Protected by IP
Header Checksum](https://image.slidesharecdn.com/networkingfundamentalstransportprotocolstcpandudp-180621134118/75/Networking-Fundamentals-Transport-Protocols-TCP-and-UDP-15-2048.jpg)
![24
QoS Classification
Payload
...
MAC Destination
MAC Destination MAC Source
MAC Source
Ethertype
0 32
Frame Check Sequence
0x8100 VIDPCP D
Ver IHL DSCP Total LengthE
ID Fl Fragment Offset
TTL Protocol Header Checksum
Source Address
Destination Address
Payload
...
[Options …]
0 32
Ethernet Header IPv4 Header
DSCP — Differentiated Services Code Point (6 bits)
ECN — Explicit Congestion Notification (2 bits)
PCP — Priority Code Point (Class of service) (3 bits)
DEI — Drop Eligible Indicator (1 bit)](https://image.slidesharecdn.com/networkingfundamentalstransportprotocolstcpandudp-180621134118/75/Networking-Fundamentals-Transport-Protocols-TCP-and-UDP-24-2048.jpg)
Uploaded byAndriy Berestovskyy
Networking Fundamentals: Transport Protocols (TCP and UDP)
The document presents an in-depth exploration of networking fundamentals, focusing primarily on transport protocols like TCP and UDP. It discusses the key features, header structures, multiplexing, and connection establishment/termination processes associated with these protocols, as well as providing insights into Quality of Service (QoS) metrics. Additionally, it outlines significant port numbers and includes references for further reading.
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Networking Fundamentals: Transport Protocols (TCP and UDP)
- 1. Andriy Berestovskyy 2017 Networking Fundamentals TransportProtocols ( ц ) А н д р і й Б е р е с т о в с ь к и й networking hour TCP UDP NAT IPsec IPv4 IPv6 internet protocolsAH ESP authentication authorization accounting encapsulation security BGP OSPF ICMP ACLSNAT tunnel PPPoE GRE ARP discovery NDP OSI broadcast multicast IGMP PIM MAC DHCP DNS fragmentation semihalf berestovskyy
- 2. Networking Fundamentals ● ComputerNetworks ● Networking Models ● Local Networks ● Internet ● IPv4 Routing ● > Transport Protocols 2
- 3. IPv4 Transport Layer 3 Application Presentation Session Transport Network DataLink Physical Frame Bits MAC Data FCS IP Data TCP Data Packet Segment Data 7 6 5 4 3 2 1 Hi! Salut!
- 4. Transmission Control Protocol ●Connection Oriented ● Ordered Delivery ● Error Recovery ● Flow Control ● Multiplexing 4 How? Other L4 protocols?
- 5. Source/Destination Port —for multiplexing Seq — seq number of the first data byte Ack — next seq number sender is expecting Data offset — size of header in 32-bit words, usually 5 Flags — Flags (ACK, PSH, RST, SYN, FIN, etc…) Window Size —size of the receive window Checksum — TCP header, data and pseudo-header Urgent Pointer — offset to last urgent byte Options — usually empty TCP Header 5 Source Port Destination Port Sequence Number Acknowledgement Number Off TCP Checksum Data ... [Options …] 0 32 Protected by TCP Checksum DataOffset Flags Window Size Urgent Pointer Pseudo header? Examples? Ver IHL DSCP Total LengthE ID Fl Fragment Offset TTL Proto = TCP IP Header Checksum Source Address Destination Address [Options …] 0 32 IHL Protected by IP Header Checksum
- 6. Transport Layer Multiplexing google.com Client 100.3.2.5 Server 1.1.1.1 DNSQUERYTo: 1.1.1.11 Src/dst IPs are the same How to distinct? HTTP GET /To: 1.1.1.12 HTTP GET logo.jpgTo: 1.1.1.13
- 7. Multiplexing using Sockets google.com Client 100.3.2.5 DNSQUERYTo: 1.1.1.1 Src: 1025 Dst: 53 1 HTTP GET /To: 1.1.1.1 Src: 1026 Dst: 80 2 HTTP GET logo.jpgTo: 1.1.1.1 Src: 1027 Dst: 8080 3 SOCKET 1: IP: 1.1.1.1 Protocol: UDP Port: 53 Why 1025? SOCKET 2: IP: 1.1.1.1 Protocol: TCP Port: 80 SOCKET 3: IP: 1.1.1.1 Protocol: TCP Port: 8080 Socket? Why 53?
- 8. Network socket —internal endpoint for sending or receiving data at a single node in a computer network — Wikipedia 8
- 9. Well-Known* Port Numbers 9 20 PortProto Service * See /etc/services for more TCP File Transfer Protocol data connectionftp-data Unix Name 21 TCP File Transfer protocol control connectionftp 22 TCP Secure shellssh 25 TCP Simple Mail Transfer Protocolsmtp 53 UDP Domain Name System requestdomain 69 UDP Dynamic Host Configuration Protocolbootps 69 UDP Trivial File Transfer Protocoltftp 80 TCP World Wide Webhttp
- 10. Socket Connections 10 Client DNS Resolver 1025 Web Browser Web Browser 1026 1027 TCP (100.3.2.5,TCP, 1027) (100.3.2.5, TCP, 1026) (100.3.2.5, UDP, 1025) IP 100.3.2.5 UDP Server DNS Server 53 Web Server Web Server 80 8080 TCP IP 100.3.2.5 UDP (1.1.1.1, TCP, 8080) (1.1.1.1, TCP, 80) (1.1.1.1, UDP, 53)
- 11. TCP Connection Establishment Server Port:80 Src: 1026, Dst: 80 SYN 132 1 Client Port: 1026 Source Port Destination Port Sequence Number Acknowledgement Number Off TCP Checksum Data ... [Options …] 0 32 Flags: SYN ACK Window Size Urgent Pointer Src: 80, Dst: 1026 SYN 69, ACK 132+1 2 Src: 1026, Dst: 80 ACK 69+1 3 11
- 12. TCP Error Recovery 12 TCPClient TCP ACK 701 Data [ ... HTTP GET / HTTP OK TCP SEQ 70 ...SEQ 80 … ]SEQ 90 ACK 80 ...SEQ 80 2 3 4 6 TCP Server 5
- 13. TCP Connection Termination Server Port:80 Src: 1026, Dst: 80 FIN 99 1 Client Port: 1026 Source Port Destination Port Sequence Number Acknowledgement Number Off TCP Checksum Data ... [Options …] 0 32 Flags: FIN ACK Window Size Urgent Pointer Src: 1026, Dst: 80 ACK 142+1 4 Src: 80, Dst: 1026 ACK 99+1 2 Src: 80, Dst: 1026 ACK 99+1, FIN 142 3 13
- 14. User Datagram Protocol ●Connection Oriented ● Connectionless ● Ordered Delivery ● Error Recovery ● Flow Control ● Multiplexing 14 Usage?
- 15. Source/Destination Port —for multiplexing Length —length of UDP header and data Checksum — header, data and pseudo-header UDP Header 15 Source Port Destination Port Length Data ... 0 32 Protected by UDP Checksum 8B UDP Checksum Pseudo header? Ver IHL DSCP Total LengthE ID Fl Fragment Offset TTL Proto = UDP IP Header Checksum Source Address Destination Address [Options …] 0 32 IHL Protected by IP Header Checksum
- 16. TCP vs UDP 16 UDPTCP Header size Feature Data unit Connection oriented Reliable transport Preserve message boundary Ordered delivery Data checksum Flow control
- 17. TCP vs UDP 17 8 UDPTCP 20-60Header size Feature Datagram SegmentData unit No YesConnection oriented No YesReliable transport Yes NoPreserve message boundary No YesOrdered delivery Optional YesData checksum No YesFlow control Flow control?
- 18. Quality of Service(QoS) — measurement of the overall performance of a service seen by the users of the network — Wikipedia 18
- 19. Bandwidth — number ofbits available per time in a communication channel End-to-end delay — time for a packet to be transmitted across a network Jitter — deviation in end-to-end delays Packet loss — rate of packets lost / packets sent Quality of Service Characteristics 19 End-to-end?
- 20.
- 21. Example Services Requirements 21 BandwidthDelay Web browsing Service Voice calling Videoconference Gaming Jitter Loss Peer-to-peer downloading
- 22. Example Services Requirements 22 Medium BandwidthDelay MediumWeb browsing Service Low LowVoice calling Medium LowVideoconference Low LowGaming Jitter Loss Medium Low Low Low Medium Low Low Low High HighPeer-to-peer downloading High High How?
- 23.
- 24. 24 QoS Classification Payload ... MAC Destination MACDestination MAC Source MAC Source Ethertype 0 32 Frame Check Sequence 0x8100 VIDPCP D Ver IHL DSCP Total LengthE ID Fl Fragment Offset TTL Protocol Header Checksum Source Address Destination Address Payload ... [Options …] 0 32 Ethernet Header IPv4 Header DSCP — Differentiated Services Code Point (6 bits) ECN — Explicit Congestion Notification (2 bits) PCP — Priority Code Point (Class of service) (3 bits) DEI — Drop Eligible Indicator (1 bit)
- 25. Transport Protocols Checklist 1.TCP services? 2. Socket? 3. TCP connection establishment? 4. UDP services? 5. TCP vs UDP? 6. QoS? 25
- 26. References 1. Kevin Wallace.CCNP Routing and Switching ROUTE 300-101 Official Cert Guide. Cisco Press, 2014 2. David Hucaby. CCNP Routing and Switching SWITCH 300-115 Official Cert Guide. Cisco Press, 2014 3. RFC 1122. Requirements for Internet Hosts — Communication Layers. 4. IANA Protocol Numbers: http://www.iana.org/assignments/protocol-numbers 26