Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 1 Cisco Systems CCNA Version 3 Semester 1 Module 10

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 2 Overview

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 3 Module 10: Routing Fundamentals and Subnets 10.1 Routed Protocol Routable and routed protocols IP as a routed protocol Packet propagation and switching within a router Internet Protocol (IP) Anatomy of an IP packet 10.2 IP Routing Protocols Routing overview Routing versus switching Routed versus routing Path determination Routing tables Routing algorithms and metrics IGP and EGP Link state and distance vector Routing protocols 10.3 The Mechanics of Subnetting Classes of network IP addresses Introduction to and reason for subnetting Establishing the subnet mask address Applying the subnet mask Subnetting Class A and B networks Calculating the resident subnetwork through ANDing

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Routable and routed protocols

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 5 The network address is obtained by ANDing the address with the network mask. The reason that a network mask is used is to allow groups of sequential IP addresses to be treated as a single unit Routable and routed protocols

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 6 IP is a connectionless, unreliable, best-effort delivery protocol. IP determines the most efficient route for data, based on the routing protocol.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide IP as a routed protocol MAC d MAC s IP s IP d P s P d

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Packet propagation and switching within a router MAC d MAC s IP s IP d P s P d Reliable connection-oriented

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 9 Frame Header MAC destination IP Header IP source MAC source IP destination Frame Trailer (FCS/CRC) Segment Header Port source Port destination MAC d MAC s IP s IP d P s P d

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 10 One Complete Maximum Frame MAC d MAC s IP s IP d P s P d Frame Header MAC addresses IP Header IP addresses Data… …Data… FCS …Data

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Packet propagation and switching within a router Each time a packet is switched from one router interface to another the packet is de-encapsulated then encapsulated once again.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Packet propagation and switching within a router MAC d MAC s IP s IP d P s P d The Empty Frame is Thrown Away… The MAC address is changed each time the packet passes through a router. The Router interface is part of the attached LAN. Like a host, the router uses the MAC address to exchange topological (physical) information.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Packet propagation and switching within a router Discarded MAC addresses Eventually these discarded Mac addresses will pile up and should be returned to the Manufacturer for recycling.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Packet propagation and switching within a router MAC d MAC s IP s IP d …and a new one is created with the Router’s Mac address.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Packet propagation and switching within a router

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 16

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Packet propagation and switching within a router

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Packet propagation and switching within a router

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Packet propagation and switching within a router

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Packet propagation and switching within a router

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Packet propagation and switching within a router

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Packet propagation and switching within a router Routers determine the subnet network address based upon a given IP address and subnet mask by binary ANDing the two together.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Packet propagation and switching within a router

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Packet propagation and switching within a router

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 25 MAC d MAC s IP s IP d P s P d Packet propagation and switching within a router

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Packet propagation and switching within a router

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Internet Protocol (IP) IP is a connectionless service. The route that the packet takes is determined by the routers.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 28 WAN Services Dedicated Physical - PPP ISDN – Private Physical Switched VPN - Public Packet Switched internet private Frame Relay - Private Packet Switched Point of Demarcation The Telephone Company owns all the infrastructure Many ways to do this.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Anatomy of an IP packet MAC d MAC s IP s IP d P s P d IP Stuff

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 30 Version – Indicates the version of IP currently used; four bits. If the version field is different than the IP version of the receiving device, that device will reject the packets. *IP header length (HLEN) – Indicates the datagram header length in 32-bit words. This is the total length of all header information, accounting for the two variable-length header fields. Type-of-service (TOS) – Specifies the level of importance that has been assigned by a particular upper-layer protocol, eight bits. Total length – Specifies the length of the entire packet in bytes, including data and header, 16 bits. To get the length of the data payload subtract the HLEN from the total length. Identification – Contains an integer that identifies the current datagram, 16 bits. This is the sequence number. *Flags – A three-bit field in which the two low-order bits control fragmentation. One bit specifies whether the packet can be fragmented, and the other specifies whether the packet is the last fragment in a series of fragmented packets. Fragment offset – Used to help piece together datagram fragments, 13 bits. This field allows the previous field to end on a 16-bit boundary. *Time-to-live (TTL) – A field that specifies the number of hops a packet may travel. This number is decreased by one as the packet travels through a router. When the counter reaches zero the packet is discarded. This prevents packets from looping endlessly. Protocol – indicates which upper-layer protocol, such as TCP or UDP, receives incoming packets after IP processing has been completed, eight bits. Header checksum – helps ensure IP header integrity, 16 bits. IP Source IP Destination Options – allows IP to support various options, such as security, variable length. *Padding – extra zeros are added to this field to ensure that the IP header is always a multiple of 32 bits. IP Stuff

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 31 Module 10: Routing Fundamentals and Subnets 10.1 Routed Protocol Routable and routed protocols IP as a routed protocol Packet propagation and switching within a router Internet Protocol (IP) Anatomy of an IP packet 10.2 IP Routing Protocols Routing overview Routing versus switching Routed versus routing Path determination Routing tables Routing algorithms and metrics IGP and EGP Link state and distance vector Routing protocols 10.3 The Mechanics of Subnetting Classes of network IP addresses Introduction to and reason for subnetting Establishing the subnet mask address Applying the subnet mask Subnetting Class A and B networks Calculating the resident subnetwork through ANDing

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Routing overview

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Routing overview The router compares available routing table information to select the best path.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Routing overview Routing metrics are values used in determining the advantage of one route over another. Routing protocols use various combinations of metrics for determining the best path for data.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Routing overview MAC d MAC s IP s IP d P s P d

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Routing versus Switching Routing is a hierarchical organizational scheme that allows individual addresses to be grouped together; the same as area codes in the telephone network. Routers must maintain routing tables and make sure other routers know of changes in the network topology. This function is performed using a routing protocol. The router must use the routing table to determine where to send packets. The router switches the packets to the appropriate interface, adds the necessary framing information for the interface, and then transmits the frame IP address ? Telephone number ? Social Security Number ? You need a subnet mask to know.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 37 This course focuses on Internet Protocol (IP). Other routable or routed protocols include DecNet, IPX/SPX, XNS and AppleTalk. These protocols provide Layer 3 support. Non-routable protocols do not provide Layer 3 support. The most common non-routable protocol is NetBEUI. NetBEUI is a small, fast, and efficient protocol that is limited to frame delivery within one segment. Routable Protocols

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Routing versus Switching 3

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Routing versus Switching E1 is just another NIC on the network. The router keeps the same arp table as any of the hosts on that network. On the WAN side, the router keeps a Routing Table. S1

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Routing versus Switching

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 41 Includes any network protocol that provides enough information in its network layer address for a router to forward it to the next device and thence to its destination. Defines the format and use of the fields within a packet. The Internet Protocol (IP) and Novell's Internetwork Packet Exchange (IPX) are examples of routed protocols. Other examples include DECnet, AppleTalk, Banyan VINES, and Xerox Network Systems (XNS). RoutED

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Routed versus routing RoutING 1.Routing Information Protocol (RIP) 2.Interior Gateway Routing Protocol (IGRP) 3.Open Shortest Path First (OSPF) 4.Border Gateway Protocol (BGP) 5.Enhanced IGRP (EIGRP). Distance Vector Link State

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 43 Distance Vector Link State EGP IGP

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Path determination Routes configured manually by the network administrator are static routes. Routes learned by others routers using a routing protocol are dynamic routes.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Path determination Each intersection is a router

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Path determination

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 47 Routing Information Protocol (RIP) uses hop count as its only routing metric. Interior Gateway Routing Protocol (IGRP) uses a combination of bandwidth, delay, load, and reliability metrics to create a composite metric value Routing tables S0

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Routing algorithms and metrics Bandwidth Delay Load Reliability

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Routing algorithms and metrics 1.Bandwidth – The data capacity of a link. Normally, a 10-Mbps Ethernet link is preferable to a 64-kbps leased line. 2.Delay – The length of time required to move a packet along each link from source to destination. Delay depends on the bandwidth of intermediate links, the amount of data that can be temporarily stored at each router, network congestion, and physical distance. 3.Load – The amount of activity on a network resource such as a router or a link. 4.Reliability – Usually a reference to the error rate of each network link. 5.Hop count – The number of routers that a packet must travel through before reaching its destination. Each router the data must pass through is equal to one hop. A path that has a hop count of four indicates that data traveling along that path would have to pass through four routers before reaching its final destination. If multiple paths are available to a destination, the path with the least number of hops is preferred. 6.Ticks – The delay on a data link using IBM PC clock ticks. One tick is approximately 1/18 second. 7.Cost – An arbitrary value, usually based on bandwidth, monetary expense, or other measurement, that is assigned by a network administrator. Bad Dogs Love Routing Hairy Tom Cats

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Routing algorithms and metrics 1.Optimization – Optimization describes the capability of the routing algorithm to select the best route. The route will depend on the metrics and metric weightings used in the calculation. For example, one algorithm may use both hop count and delay metrics, but may consider delay metrics as more important in the calculation. 2.Simplicity and low overhead – The simpler the algorithm, the more efficiently it will be processed by the CPU and memory in the router. This is important so that the network can scale to large proportions, such as the Internet. 3.Robustness and stability – A routing algorithm should perform correctly when confronted by unusual or unforeseen circumstances, such as hardware failures, high load conditions, and implementation errors. 4.Flexibility – A routing algorithm should quickly adapt to a variety of network changes. These changes include router availability, router memory, changes in bandwidth, and network delay. 5.Rapid convergence – Convergence is the process of agreement by all routers on available routes. When a network event causes changes in router availability, updates are needed to reestablish network connectivity. Routing algorithms that converge slowly can cause data to be undeliverable.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide IGP and EGP Interior Gateway Protocols Exterior Gateway Protocols (RIP) and (RIPv2) (IGRP) (EIGRP) (OSPF) (IS-IS)

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Link state and distance vector IGPs can be further categorized as either: 1.Distance-Vector protocols - RIP IGRP EIGRP Routing by rumor 2.Link-State protocols. Link-state advertisements are caused by… topology changes link-state refresh packets 1.Distance-Vector protocols “Psst! Hey neighbor, remember who I know about?” 2.Link-State protocols. “Listen up everybody, there’s a change to the networks that I’m connected to.”

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 53 Module 10: Routing Fundamentals and Subnets 10.1 Routed Protocol Routable and routed protocols IP as a routed protocol Packet propagation and switching within a router Internet Protocol (IP) Anatomy of an IP packet 10.2 IP Routing Protocols Routing overview Routing versus switching Routed versus routing Path determination Routing tables Routing algorithms and metrics IGP and EGP Link state and distance vector Routing protocols 10.3 The Mechanics of Subnetting Classes of network IP addresses Introduction to and reason for subnetting Establishing the subnet mask address Applying the subnet mask Subnetting Class A and B networks Calculating the resident subnetwork through ANDing

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Classes of network IP addresses EG: An IP address and a default subnet mask, the host belongs to the network.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Introduction to and reason for subnetting The benefits of Subnetting 1.smaller broadcast domains 2.low-level security provided 3.increased address flexibility EG: In a class C network a subnet mask of will create 6 useable subnets each with 32 useable hosts.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Introduction to and reason for subnetting Host bits are reassigned as network bits. Host bits of the network address are all equal to 0. Host bits of the broadcast address are all equal to 1.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Introduction to and reason for subnetting

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Establishing the subnet mask address

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Establishing the subnet mask address Assume Class C subnetting

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Establishing the subnet mask address

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Establishing the subnet mask address Magic Numbers

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Applying the subnet mask Assumes subnet mask of resulting in a magic number = 32

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Applying the subnet mask Magic Numbers

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Subnetting Class A and B networks 16 bits are available for Class B host IP addresses using the default subnet mask. If you applied the subnet mask to a Class B network it would give you 254 useable subnets and 254 useable hosts/subnet. Applying the subnet mask (/28) to a Class B network will give 4094 useable subnets and 14 useable hosts/subnet.

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Subnetting Class A and B networks To borrow 20 bits you would use subnet mask = /28

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Subnetting Class A and B networks

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Subnetting Class A and B networks

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Subnetting Class A and B networks

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Calculating the resident subnetwork through ANDing

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide Calculating the resident subnetwork through ANDing

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 71

Nov-03 ©Cisco Systems CCNA Semester 1 Version 3 Comp11 Mod10 – St. Lawrence College – Cornwall Campus, ON, Canada – Clark slide 72 FIN