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© 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 1 Nir Ingbar Introduction to Networking (Routing & Switching)

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Presentation on theme: "© 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 1 Nir Ingbar Introduction to Networking (Routing & Switching)"— Presentation transcript:

1 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 1 Nir Ingbar Introduction to Networking (Routing & Switching)

2 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 2 Agenda  OSI 7 Layers model  Layer 1 & 2  Frame forwarding & filtering  VLAN, dot1Q Trunking  IP  Routing

3 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 3 OSI 7 Layers model (1977 by ISO)

4 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 4 OSI Model Layer’s definitions Each OSI layer performs unique and specific task A layer only has a knowledge of its adjacent layers A layer uses the services of a layer below A layer performs functions and provides service to the layer above A layer service is independent of its implementation Application Presentation Session Data Link Physical Transport Network

5 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 5 OSI Model Layers Physical: Electrically encodes and physically transfers messages between nodes Data Link: Provides reliable transit of data across a physical link, handling physical addressing, link discipline, error detection, ordered delivery of frames and flow control Network: Provides connectivity and path selection between two end systems that may be located on geographically diverse sub- networks Transport: End- to- end control & information exchange with a level of reliability required for the applications

6 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 6 OSI Model Layers (cont.) Session: Manages the connection between cooperating applications Presentation: Transforms data to and from negotiated standardized formats Application: Provides the window between the application process and OSI

7 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 7 Data encapsulation Application Presentation Session Data Link Physical Transport Network Application Presentation Session Data Link Physical Transport Network Data Data Unit SH TH Data Unit NH Data Unit DLHFCS Bits * FCS (Frame Check Sequence)

8 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 8 Internetworking Devices Application Presentation Session Data Link Physical Transport Network Application Presentation Session Data Link Physical Transport Network Hub/Repeater Switch/Bridge Router

9 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 9 Protocol Suite Application Presentation Session Transport Network Data Link Physical TelnetFTPSMTPTFTPBOOTPSNMP TCPUDP IP ICMP ARP Ethernet, Token Ring, FDDI, WAN synchronous

10 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 10 Layer 1 & 2

11 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 11 Device Types  Hub - multi port repeater, provide connectivity, allowing attached devices a path between which they can communicate, works on layer one  Switch – connecting hosts  Bridge – connecting networks, can’t identify different logical networks

12 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 12 Bridge vs. Switch  Bridge usually have two interfaces and can connect to physical networks  Switches usually have more than that  The main difference between a switch and bridge is the number of networks each can connect  Switches are often aimed to connect workstations in a single junction  Both are used inside LAN  Both operates on layers one and two

13 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 13 Collision Domain  one of the logical network segments in which the data packets can collide to each other  Collision domains are often referred as ‘Ethernet segments'.  defined as a single CSMA/CD network segment in which there will be a collision if two computers attached to the system both transmit at the same time  A collision occurs when two or more network devices are trying to transmit packets at the exact same time

14 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 14 Collision domain - example

15 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 15 Collision domain - example

16 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 16 Type Of Transmission  Unicast - unicast transmission is the sending of information packets to a single destination  Broadcast - broadcasting refers to transmitting a packet that will be received (conceptually) by every device on the broadcast domain  Multicast - multicast is a network addressing method for the delivery of information to a group of destinations simultaneously  Anycast – like multicast but only one address of a set of addresses is chosen at any given time to receive information from any given sender

17 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 17 MAC Address  48 bits (6 octets) address space representing an unique identifier to most network adapters or network interface cards (NIC)  The first three octets identify the organization that issued the identifier and are known as the Organizationally Unique Identifier (OUI)  D3-C4-55-6A

18 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 18 Broadcast Domain  represents the systems to which a given broadcast will travel  broadcasts do not pass routers by default  If one station will broadcast, all the stations in this domain will get the message  If a station wants to send a message out of the LAN, it will have to know it’s Default Gateway

19 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 19 Broadcast domain – simple example

20 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 20 Collision domain- problem

21 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 21  One switch can be a Single Point Of Failure  Adding an additional Switch can create broadcast storm.

22 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 22  On running this algorithm the LAN is reduced to an acyclic tree  The main idea of the Spanning Tree is for the bridges to select the ports over which they will forward frames Solution: STP – Spanning tree Protocol

23 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 23 Spanning Tree Protocol With Spanning Tree B5B3 L2L1 L3L4L5 B1 B2B4 L4L3 Actual Network L2 L5 L1 B1 B4B3 B5 B2 X X Spanning tree is designed to prevent loops in bridged/switched Ethernet network based on the root bridge concept, which is selected via programmable parameters

24 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 24 Frame forwarding & filtering

25 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 25 Frame forwarding & filtering The initial MAC address is empty

26 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 26 Frame forwarding & filtering (cont.) Station A sends a frame to station C The switch caches the MAC address of station A to port E0 by learning the source address of data frames The frame from station A to station C is flooded out to all ports except port E0

27 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 27 Frame forwarding & filtering (cont.) Station D sends a frame to station C The switch caches the MAC address of station D to port E3 by learning the source address of data frames The frame from station D to station C is flooded out to all ports except port E3

28 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 28 Frame forwarding & filtering (cont.) Station A sends a frame to station C The destination is known; the frame is not flooded

29 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 29 VLAN, dot1Q Trunking

30 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 30 VLAN, dot1Q Trunking 802.1Q Frame FCS (Frame Check Sequence) is recalculated

31 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 31 Importance of native VLANs VLAN 1 untagged traffic (native VLAN) An 802.1Q trunk and its associated trunk ports have a native VLAN value Q does not tag frames for native VLAN. Therefore, ordinary stations will be able to read the native untagged frames, but will not be able to read any other frame because the frames are tagged

32 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 32 IP

33 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 33 Internet Protocol - IP Network Layer Provides network layer services to TCP/IP protocol suite Responsible for forwarding packets through network based on IP addresses “ Best effort” delivery Connectionless Unacknowledged Relies on a transport protocol to guaranty delivery

34 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 34 IPv4 Addressing Address format: XXX.XXX.XXX.XXX (0≤XXX ≤ 255) Addresses are 32 bits long (4,294,967,296 IP addresses) Internet Assigned Numbers Authority (IANA) assigns IP addresses for the Internet Divided into five classes three of which are available to end-user networks Consists Network and Host identification fields

35 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 35 Available IP Addresses  Class D is reserved for multicast groups  Class E is reserved for future use ClassAssigned Network/ /Host ID Range of Network IDsMax. Hosts Per Network A /8NET.X.X.X1 –12616,777,214 B /16NET.NET.X.X128.1 – ,534 C /24NET.NET.NET.X –

36 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 36 Private Networks ClassAssigned Network/ /Host ID Range of Network IDs ANET.X.X.X BNET.NET.X.X CNET.NET.NET.X  RFC 1918 addresses Not routed by Internet routers (filtered by Edge Routers)  RFC 2026—Link Local Addresses – Auto-assigned IP address to local host if DHCP server cannot be contacted Not routed by any router

37 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 37 Other Reserved Addresses  – Reserved for testing and loopback routines for IP Applications ping —verifies the local host has properly loaded the IP protocol  – —Class D multicast (IANA) Reserved for well known services and network topology mechanisms

38 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 38 Subnetting IP/VLSM/Classless Allows to divide a single IP network into smaller divisions – Subnets Done by borrowing bits from the host portion of the address Subnet bits are defined by the Subnet Mask IP Address Subnet Mask Or /20 Subnet Host

39 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 39 Summary Host-to-Host Packet Delivery (1 of 22)

40 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 40 Host-to-Host Packet Delivery (2 of 22)

41 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 41 Host-to-Host Packet Delivery (3 of 22)

42 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 42 Host-to-Host Packet Delivery (4 of 22)

43 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 43 Host-to-Host Packet Delivery (5 of 22)

44 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 44 Host-to-Host Packet Delivery (6 of 22)

45 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 45 Host-to-Host Packet Delivery (7 of 22)

46 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 46 Host-to-Host Packet Delivery (8 of 22)

47 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 47 Host-to-Host Packet Delivery (9 of 22)

48 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 48 Host-to-Host Packet Delivery (10 of 22)

49 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 49 Host-to-Host Packet Delivery (11 of 22)

50 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 50 Host-to-Host Packet Delivery (12 of 22)

51 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 51 Host-to-Host Packet Delivery (13 of 22)

52 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 52 Host-to-Host Packet Delivery (14 of 22)

53 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 53 Host-to-Host Packet Delivery (15 of 22)

54 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 54 Host-to-Host Packet Delivery (16 of 22)

55 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 55 Host-to-Host Packet Delivery (17 of 22)

56 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 56 Host-to-Host Packet Delivery (18 of 22)

57 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 57 Host-to-Host Packet Delivery (19 of 22)

58 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 58 Host-to-Host Packet Delivery (20 of 22)

59 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 59 Host-to-Host Packet Delivery (21 of 22)

60 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 60 Host-to-Host Packet Delivery (22 of 22)

61 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 61 Default Gateway

62 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 62 Routing

63 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 63 Routers Routers have the following components: – CPU – Motherboard – RAM – ROM Routers have network adapters to which IP addresses are assigned. Routers may have the following two kinds of ports: – Console: For the attachment of a terminal used for management – Network: Different LAN or WAN media ports Routers forward packets based upon a routing table

64 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 64 Router Functions  Lets other routers know about changes  Determines where to forward packets  Translate between different layer2 protocols/interfaces RouterX# show ip route D /24 [90/ ] via R /24 [120/4] via O /24 [110/229840] via

65 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 65 Routing Types Static/Dynamic IGP (Interior Gateway Protocol) – RIP, ISIS, OSPF, (E)IGRP EGP (Exterior Gateway Protocol) - BGP

66 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 66 Path Determination

67 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 67 Routing Tables

68 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 68 Routing Table Entries  Directly connected: Router attaches to this network  Static routing: Entered manually by a system administrator  Dynamic routing: Learned by exchange of routing information  Default route (optional): Statically or dynamically learned; used when no explicit route to network is known

69 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 69 Routing Metrics

70 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 70 Distance Vector Routing Protocols Passes periodic copies of routing table to neighbor routes and accumulates distance vectors

71 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 71 Link-State Routing Protocols All routers calculate “shortest paths” using Djikstra algorithm After initial flood, passes small event-triggered link-state updates to all other routers

72 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 72 Routing Protocols Distance Vector – RIP, IGRP Link State – OSPF, ISIS Balanced hybrid - EIGRP

73 © 2006 Cisco Systems, Inc. All rights reserved.Cisco ConfidentialPresentation_ID 73 Administrative Distance Route SourceDefault Distance Connected0 Static1 eBGP20 EIGRP90 IGRP100 OSPF110 ISIS115 RIP120 iBGP200 Unknown*255 * If the administrative distance is 255, the router does not believe the source of that route and does not install the route in the routing table


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