Networking basics
Download as PPT, PDF1 like747 views
This document provides an overview of networking concepts including network components, layers of the OSI model, network structures, IP addressing, subnetting, routing, and TCP/IP protocols. Key points covered include the core, distribution, and access layers of a network hierarchy; functions of the physical, data link, network, and transport layers; MAC addressing; IP addressing classes and subnetting; TCP and port numbers; and routing protocols.
Networking basics
- 2. Defining components of the network home office internet mobile users Branch office Main Office
- 3. Network Structure Defined by Hierarchy Core Layer Distribution Layer Access Layer
- 4. Access Layer Characteristics Access Layer End Station entry point to the network
- 5. Distribution Layer Characteristics •Access Layer Aggregation Point •Routes Traffic •Broadcast/Multicast Domains •Media Translation •Security •Possible point for remote access
- 6. Core Layer Characteristics •Fast Transport to enterprise services •No packet manipulation
- 7. TCP/IP Protocol Layers Application Presentation Session Transport Network Data Link Physical OSI Reference Model
- 8. OSI Model Overview Application Presentation Session Transport Network Data Link Physical Application Layers Data Flow Layers Telnet, FTP JPEG, ASCII Operating System TCP, UDP, SPX IP, IPX HDLC EIA/TIA-232 V.35
- 9. Encapsulating/Decapsulating Data Application Presentation Session Transport Network Data Link Physical Application Layers Data Flow Layers PDU PDU PDU Segment Packet Frame Bits
- 10. Physical Layer Functions Defines: Media type Connector Type Signaling type • Only one station on a shared Ethernet segment can send a frame at one time but all Stations receive and look at the frame to determine if it is for them • All end stations on a segment that hear all the traffic on the wire are in the same collision domain. • Station that are in the same collision domain are always in the same broadcast domain
- 11. Hubs Operate at Physical Layer HUBS ARE USED TO EXTEND THE PHYSICAL MEDIA • All devices in the same collision domain • All devices in the same broadcast domain • Devices share the same bandwidth
- 12. Hubs: One Collision Domain • More end stations means more collisions • CSMA/CD is used
- 13. LAN Physical Layer Physical Layer Implementations Vary MODULE TYPE HALF/FULL DUPLEX Ethernet 10base2 185m max Coax (802.3) 10base5 500m max Cat 3,4,5(2-pair) 10BaseT 100/100m Cat 5 (2-pair)-802.3u 100BaseTX 100/100m Multimode Fiber 10BaseFL 2/2Km -802.3u- 100BaseFX 400/2Km Single Mode Fiber-802.3u-100BaseFX10/10Km
- 14. UTP device RJ-45 Connector PIN WIRE PAIR 1 Pair 3 T2 2 Pair 3 R2 3 Pair 2 T3 4 Pair 1 R1 5 Pair 1 T1 6 Pair 2 R3 7 Pair 4 T4 8 Pair 4 R4 RJ-45 Straight: 1-to-1, 2-to-2 e.t.c. RJ-45 Crossover: 1-to-3, 2-to-6 e.t.c.
- 15. WAN Physical Layer Physical Layer Implementations Vary HDLC PPP FRAME RELAY ISDN BRI (WITH PPP) EIA/TIA-232 RJ-45 EIA/TIA-449 (greater distance than 232,for same bit rate) Note: Pinouts are X.21 V.24 V.35 HSSI different than LAN RJ-45 DTE (Router’s interface) • End of user’s device on the WAN link (Router’s interface) DCE (e.g. modem) • End of the WAN provider’s side of the communication facility • DCE is responsible for clocking
- 16. Data Link Layer Functions DEFINES: • Physical source and destination addresses • Network topology • Frame sequencing • Flow Control • Connection-oriented or Connectionless
- 17. Data Link Layer Functions (continued) 8 6 6 2 Variable 4 Preamble Destinat Address Source Addres s Length Data FCS MAC ADDRESS 0000.0C XX.XX.XX IEEE assigned Vendor assigned
- 18. MAC Address
- 19. Switches and Bridges Operating at Layer 2 • Each segment (port) has its own collision domain • ALL segments are in the same broadcast domain • Layer-2 switching is hardware-based bridging (ASIC) • Layer-2 bridging is software-based • Bridges can have up to 16 ports • One STP/BRIDGE, many STP/switch • All segments must use the same data link implementation (Ethernet or token ring for example) otherwise need router for translation • One device/segment can send frames at the same time
- 20. Internet Layer Overview Internet Protocol (IP) Internet Control Message Protocol (ICMP) Address Resolution Protocol (ARP) Reverse Address Resolution Protocol (RARP) Application Transport Internet Data Link Physical OSI network layer corresponds to the TCP/IP internet layer
- 21. Network Layer Functions IP Header Source Address Destination Address Data Logical Address 172.15.1.1 Two types of Network Layer Packets • Network Layer Data Packets- Include upper layer control/user data • Route Discovery/Update Packets- Sent between routers (include information about e.g. distance between two networks, information for how to reach this network) • Need to know addressing which usually provide hierarchy in the network
- 22. Network Layer Functions (continued) 1.0 1.2 1.1 2.1 2.2 3.0 3.2 3.1 Routing Table Routing Table Network Interface Metric 1 E0 0 2 S0 0 4 S0 1 Network Interface Metric 1 S0 1 2 S0 0 4 E0 0
- 23. Introduction to TCP/IP Addresses 172.18.0.1 172.18.0.2 172.16.0.1 172.17.0.1 172.17.0.2 172.16.0.2 10.13.0.0 192.168.1.0 10.13.0.1 192.168.1.1 HDR SA DA DATA
- 24. IP Addressing Address Mask 172.16.122.204 255.255.0.0 10101100 00010000 01111010 11001100 11111111 11111111 00000000 00000000 NETWORK HOST
- 25. IP Addressing
- 29. Determining Available Host Addresses
- 30. Subnet Addressing 172.16.2.200 172.16.2.2 172.16.2.160 172.16.2.1 172.16.3.1 E0 E1 172.16.3.5 172.16.3.100 172.16.3.150 172.16 . 2 . 160 Network Subnet Host
- 31. Subnet Mask
- 32. Decimal Equivalents of Bit Patterns
- 33. Subnet Mask without Subnets
- 34. Subnet Mask with subnets • Network Extended by Eight Bits
- 35. Subnet Mask with Subnets • Network Number extended by ten bits
- 36. Broadcast Addresses 172.16.1.0 172.16.3.0 172.16.2.0 172.16.4.0 172.16.3.255 (Directed Broadcast) 255.255.255.255 (Local Network broadcast) 172.16.255.255 (all subnets broadcast)
- 37. Exercise ADDRESS CLASS NETWORK HOST 10.2.2.1 128.63.2.100 201.222.5.64 192.6.141.2 256.241.201.10 130.113.64.16
- 38. Exercise Subnet Mask ADDRESS CLASS NETWORK HOST 172.16.2.10 255.255.255.0 10.6.24.20 255.255.240.0 10.30.36.12 255.255.255.0
- 39. Exercise Broadcast address ADDRESS Subnet Mask Class Subnet Broadcast 201.222.10.60 255.255.255.248 15.16.193.6 255.255.248.0 128.16.32.13 255.255.255.252 153.50.6.27 255.255.255.128
- 40. Finding the IP address of the LAN
- 41. Address Resolution Protocol 172.16.3.1 172.16.3.2 IP: 172.16.3.2 = ??? IP: 172.16.3.2 Ethernet: 080A.0B20.118C Map IP MAC I need the Ethernet address of 176.16.3.2 Local ARP I heard that broadcast. The message is for me. Here is my Ethernet address
- 42. Reverse ARP Ethernet: 080A.0B20.118C IP=??? Ethernet: 080A.0B20.118C IP: 172.16.3.2 Map MAC IP What is my IP Adress? I heard that broadcast. Your IP address is 172.16.3.25
- 43. What is a Variable-Length Subnet Mask? 172.16.14.32/27 A 172.16.14.64/27 B 172.16.14.96/27 C 172.16.14.132/30 172.16.14.136/30 172.16.14.140/30 172.16.1.0/24 HQ 172.16.0.0/16 172.16.2.0/24
- 44. Calculating VLSMs 172.16.32.0/26 172.16.32.64/26 172.16.32.128/26 172.16.33.0/30 172.16.33.4/30 172.16.33.8/30 HQ 172.16.33.12/30 172.16.32.192/26 Derived from the 172.16.33.0/26 subnet 30-bit mask (2 hosts) 26-bit mask (62 hosts) Derived from the 172.16.32.0/20 Subnet
- 45. Exercise: Calculating VLSMs 25 Users 25 users 25 users HQ 25 users Using VLSMs, define appropriate subnets for addressing the networks using 192.168.49.0/24 25 users A B C D E HQ Address for WAN links A Serial______________ B Serial______________ C Serial______________ D Serial______________ E Serial______________ A B C D E
- 46. What is Route Summarisation? 172.16.25.0/24 172.16.26.0/24 172.16.27.0/24 A B Routing Table 172.16.25.0/24 172.16.26.0/24 172.16.27.0/24 I can route to thw 172.16.0.0/16 Routing Table 172.16.0.0/16 network • Routing protocols can summarize addresses of several networks into one address
- 47. Summarizing within an Octet
- 48. Summarizing Addresses in a VLSM -Designed Network 172.16.128.0/20 B 172.16.14.64/26 C 172.16.64.0/20 D A 172.16.14.128/26 172.16.128.0/20 172.16.32.0/24 172.16.64.0/20 172.16.0.0/16 Corporate Network
- 49. Implementation Considerations • Multiple IP addresses must have the same highest-order bits • Routing decisions are made based on the entire address • Routing protocols must carry the prefix (subnet mask) length
- 50. Route Summarization Operation in Cisco Routers 172.16.5.33 /33 Host 172.16.5.32 /27 Subnet 172.16.5.0 /24 Network 172.16.0.0 /16 Block of Networks 0.0.0.0 /0 Default • Supports host-specific routes, blocks of networks, default routes • Routers use the longest path
- 51. Routers: Operate at the Network Layer • Broadcast control • Multicast control • Optimal Path Determination • Traffic Management • Logical Addressing • Connects WAN services
- 52. Transport Layer Functions • Distinguishes between upper layer applications • Establishes end-to-end connectivity between applications • Defines flow control • Provides reliable/unreliable services for data transfer
- 53. TCP Segment Format Source Port (16) Destination Port (16) Sequence Number (32) Acknowledgement Number (32) Header Length (4) Reserved (6) Code Bits (6) Window (16) Checksum (16) Urgent (16) Options (0 or 32 if any)
- 54. Port Numbers FT P T EL NET S MT P DNS TFT P S N MP R I P 21 23 25 53 69 161 520 TCP UDP
- 55. TCP Port Numbers Source Telnet Z Port Dest Port ... Host A Host Z SP DP 1028 23 ... Dest. port = 23. Send packet to my Telnet application
- 56. TCP Three way Handshake/Open Connection Host A Send SYN (seq=100 ctl=SYN) SYN received Established (seq=101 ack=301 ctl=ack) Host B SYN received Send SYN, ACK (seq=300 ack=101 ctl=syn, ack)
- 57. TCP Simple Acknowledgment Send 1 Receive ACK 2 Send 2 Receive ACK 3 Send 3 Receive ACK 4 Send 1 Receive ACK 2 Send 2 Receive ACK 3 Send 3 Receive ACK 4 Window size = 1
- 58. TCP Sequence and Acknowledgment Numbers Source Port Dest Port Sequence # I just sent #11 I just got #11, now I need #12 Acknowledgment # ... Source Dest. Seq. Ack. 1028 23 10 100 Source Dest. Seq. Ack. 1028 23 11 101 Source Dest. Seq. Ack. 1028 23 100 11 Source Dest. Seq. Ack. 1028 23 101 12
- 59. TCP Windowing Window size = 3 Send 1 Window size = 3 Send 2 Window size = 3 Send 3 Window size = 3 Send 3 Window size = 3 Send 4 Window size = 3 ACK 3 Window size = 2 ACK 5 Window size = 2 Receiver Packet 3 is dropped Sender
- 60. UDP Segment Format Source port (16) Destination Point Length (16) Checksum (16) Data (if any) No sequence or acknowledgment fields