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Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Routing Chapter 8 Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Objectives • Explain how routers work • Describe dynamic routing technologies • Install and configure a router successfully Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Historical/Conceptual How Routers Work Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) How Routers Work • Hardware that forwards packets based on destination IP address • Works at the Network layer of the OSI model – Internet layer of the TCP/IP model • Typically dedicated boxes with at least two connections • Popular router: Cisco 2600 Series Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.1 Cisco 2611 router Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) How Routers Work (cont’d.) • Home router – First exposure to a router for most techs – May combine router, switch, firewall, and DHCP server • Functions of all routers – Connect two networks (or subnets/LANs) – Examine packets and send to proper destination Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.2 Business end of a typical home router Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.3 Cisco router diagram Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.4 Linksys home router diagram Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Test Specific Routing Tables Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Routing Tables • Packets come into the router for handling • The router strips off Layer 2 information – Drops IP packet into a queue based on arrival time • The router inspects the destination IP address • The router sends the IP packet out the correct port • The routing table tells the router where to send packets Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.5 Incoming packets Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.6 All incoming packets stripped of Layer 2 data and dropped into a common queue Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) What’s Up with Layer 2? • Example: home router (See Figure 8.7) – Two ports • One connects to ISP • One connects to built-in four-port switch – Each row in table defines a single route – Each column identifies specific criteria • Destination LAN IP • Subnet mask Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.7 Routing table from a home router Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) What’s Up with Layer 2? (cont’d.) • The router examines the destination LAN IP and subnet mask to see if the packet matches that route • Gateway – Identifies the IP address for the next hop router • Interface – Identifies which router port to use (LAN or WAN) Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.8 Routing table showing the route for a packet Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) The Router and the Routing Table • The router reads every line in the router table and then decides what to do – May read top down or bottom up – A zero (0) means “anything” • Default route for the router in the example – Shown on third line of the routing table • Every node on the network has a routing table – Computer, printer, etc. Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.9 The network based on the routing table in Figure 8.7 Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Routing Table Information • Windows routing table (next slide) – Computer IP address: 10.12.14.201/24 – Computer loopback: 127.0.0.1 • Metric – Relative value defining the “cost” of using a route – If more than one route exists, route with lower metric value is used – If route fails, alternate route used Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.10 Two routes to the same network Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.11 When a route no longer works, the router automatically switches Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Computer Routing Table • Line 1 (beginning 0.0.0.0) defines the default route – (Any destination address) (with any subnet mask) (forward it to my default gateway) (using my NIC) (metric of 25 to use this route) Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Computer Routing Table • Lines 2, 3, and 4 tell the system how to handle the loopback address – No matter how you use a loopback address, as long as you start the address with 127, it will always go to 127.0.0.1 Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Computer Routing Table (cont’d.) • Line 5 (beginning with 10.12.14.0) defines the local connection – (Any packet for the 10.12.14.0) (/24 network ID) (don’t use a gateway) (just ARP on the LAN interface to get the MAC address and send it directly to the recipient) (cost of 1 to use this route) Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Computer Routing Table (cont’d.) • Line 6 (beginning with 10.12.14.201) – Anything addressed to this machine should go right back to it through the loopback (127.0.0.1) • Line 7 is the directed broadcast • Lines 8 and 9 are for the multicast address range • Bottom lines define the default IP broadcast Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Freedom From Layer 2 Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) The Functions of Routers • Connect different network technologies • Strip off all Layer 2 data • Connect to almost anything that stores IP packets Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Non-Ethernet Network Technologies • Examples – Data Over Cable Service Interface Specification (DOCSIS) – Frame Relay – Asynchronous Transfer Mode (ATM) • All carry IP packets inside their Layer 2 encapsulations Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Added Ports • Most commercial-grade routers allow adding ports – Cisco routers come with removable modules – Connecting Ethernet to ATM • Buy an Ethernet and an ATM module – Connecting Ethernet to DOCSIS • Buy an Ethernet and a DOCSIS module Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.12 Modular Cisco router Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Network Address Translation (NAT) Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Network Address Translation • TCP/IP problems – Malicious programmers target IP addresses – IPv4 addresses are not readily available • NAT enables routers to hide IP addresses of computers on a LAN from outside networks – Enables communication with outside networks • NAT extended the useful life of IPv4 addressing Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) The Setup • Acquire a block of unique IP addresses from an ISP • Assign an IP address to each computer and to the LAN connection on the router • Assign IP address of the ISP’s router to the WAN connection on the local router • Give all LAN hosts the IP address of the gateway router: can act as a default gateway Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.13 Network setup Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Basic NAT and Port Address Translation (PAT) • Basic NAT – Translates internal IP address to global IP address on a one-to-one basis • PAT – Uses port numbers to map traffic from specific machines in the network – Example: Figure 8.14 Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.14 John’s network setup Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.15 PAT in action -- changing the source IP address and port number to something usable on the Internet Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) NAT Translation Table • Used by the router to determine which IP address to put back on the packet – Sends the packet to the correct computer on the network • Mapping enables perfect tracking of packets Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) SNAT and Port Forwarding • Static NAT (SNAT) – Maps a single routable IP address to a single machine • Port forwarding – Designates a specific local address for various network services – Hides a service hosted inside your network by changing the default port number for that service Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.16 Setting up port forwarding on a home router Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.17 Changing the URL to access a Web site using a nondefault port number Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Configuring NAT • Home routers often have NAT turned on by default – The router is set to Gateway • To turn off NAT, set the radio button to Router Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.18 NAT setup on home router Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.19 Configuring NAT on a commercial-grade router Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Dynamic Routing Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Background • Routers have static routes – Manually entered – Detected at setup by the router Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Dynamic Routing Protocols • Routers communicate among themselves with change information – Update each other on changes about direct connections and distant routers • A passage of a packet through a single router is a hop Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.20 Lots of routers Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.21 Hopping through a WAN Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Routing Metrics • Routing tables contain metrics—a relative value that routers use when there is more than one route to another network – Metrics determine which route to use – Route with lowest-value metric is selected Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Common Criteria for Determining a Metric • Hop count – The number of routers a packet will pass through on the way to its destination network • Bandwidth: connection speed • Latency – Issues that may slow network traffic over given links • Cost Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Distance Vector • First of the TCP/IP routing protocols • The protocol’s cornerstone is total cost • Simple total cost adds up the hop count between a router and a destination network • Example: four routers connected as shown in Figure 8.22 – Static routes are set up with metrics shown Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.22 Getting a packet from Network ID X to Network ID Y? No clue! Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.23 Routes updated Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.24 Updated routing tables Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.25 Deleting higher-cost routes Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.26 Argh! Multiple routes! Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.27 Last iteration Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Convergence • Point at which the updating of all routing tables is complete – Also called steady state • Routers that use distance vector routing protocols continue to send each other entire routing tables • If a route breaks, the router cannot send to that destination until router table is updated Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Routing Information Protocol (RIPv1) • Oldest distance vector routing protocol – Dates from the 1980s; predecessors date to the 1960s • Maximum hop count of 15 • Routing table request could loop all the way back to the initial router • Sent out an update every 30 seconds – Caused huge network overloads Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) RIPv1 (cont’d.) • Did not work with Variable-Length Subnet Masking (VLSM) • No authentication ► left routers open to hackers sending false routing table information Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) RIPv2 • Current version of RIP – Adopted in 1994 • Fixed many problems with RIPv1 – VLSM support added – Authentication built into the protocol – Most routers still support RIPv2 Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.28 Setting RIP in a home router Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) BGP • Growth of the Internet in the 1980s led to changes initiated through Internet governing entities – Internet Society (ISOC) – Internet Assigned Numbers Authority (IANA) – Internet Engineering Task Force (IETF) Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) BGP (cont’d.) • Internet reorganized into a multitier structure • Autonomous System (AS) – Top tier – One or more networks governed by a single dynamic routing protocol within that AS – Does not use IP address, but rather uses a globally unique Autonomous System Number (ASN) assigned by IANA Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.29 The Internet Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.30 Configuring a Cisco router to use an ASN Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) BGP (cont’d.) • Autonomous Systems communicate with each other using an Exterior Gateway Protocol (EGP) • Network or networks within an AS communicate with Interior Gateway Protocols (IGPs) • Neither of these are dynamic routing protocols Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) BGP (cont’d.) • Many protocols are used within Autonomous Systems, such as RIP • The Internet uses one protocol for communication between each AS: the Border Gateway Protocol (BGP) – Current version: BGP-4 Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Connecting Autonomous Systems • BGP listed by CompTIA as a hybrid routing protocol; more technically a path vector routing protocol • Has different types of routing tables – Routers are manually configured • Advertise information passed to them from different Autonomous Systems’ edge routers – Forwards advertisements that include the ASN and other non-IP information Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Connecting Autonomous Systems (cont’d.) • BGP handles tasks unique to the Internet • Most BGP routers will ignore unreliable routes • BGP supports policies that ISPs can use to limit who and how other routers may access them • BGP supports route aggregation Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Link State • Dynamic routing protocol that announces and forwards individual route changes as they occur • Only two link state dynamic routing protocols: – Open Shortest Path First (OSPF) – Intermediate System to Intermediate System (IS-IS) Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Open Shortest Path First (OSPF) • Most commonly used IGP in the entire Internet • Designed to work within a single AS • Converges dramatically faster than RIP • Complex protocol for routers – Not found on cheap home routers – Requires a great deal of computational power Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) OSPF (cont’d.) • First launch of an OSPF-capable router – Router sends out link state advertisements (LSAs) called Hello packets • Looking for other OSPF routers – Sends out lots of LSA Hellos on first boot (flooding), and periodically thereafter Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.31 Hello! Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) OSPF (cont’d.) • OSPF cost formula – 100,000,000 / bandwidth in bps • A 10BaseT link’s OSPF cost is: 100,000,000 / 10,000,000 = 10 – The faster the bandwidth, the lower the cost – Can be overridden manually Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.32 Link states Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) OSPF (cont’d.) • OSPF routers exchange information and update their link state databases • LSA Hellos forward to every OSPF router • Within a few seconds, every router knows the link state for every other router • Routers can be grouped into areas – With multiple areas, the central area is the backbone Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) OSPF (cont’d.) • • • • The backbone has an Area ID of 0 Area border routers (ABRs) interconnect areas OSPF areas almost instantly gain convergence After convergence, each router in the area sends Hello LSAs about every 30 minutes • OSPF routers also keep alternate routes to the same network ID Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.33 Area defined Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) OSPF (cont’d.) • OSPFs popularity – Scales to large networks quite well – Supported by nearly all routers – Supports authentication – Shortest-path-first method prevents loops Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) OSPF (cont’d.) • If link breaks between routers A and B: – Routers A and B detect the break – Each router attempts to reconnect – After a few seconds of failures, router sends out an LSA announcing the broken link – Only sends single changed route, not the entire table – Each router updates its routing table Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.34 Announcing a disconnect Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) OSPF (cont’d.) • OSPF’s popularity – Scales to large networks – Supported by all but the most basic routers – Supports authentication – Shortest-path-first method prevents loops • Until recently OSPF did not support IPv6 Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Intermediate System to Intermediate System (IS-IS) • A link state dynamic routing protocol • Similar to OSPF • Applies the concept of areas and sending only updates to routing tables • Worked with IPv6 from the start • The de facto standard for ISPs Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Enhanced Interior Gateway Routing Protocol (EIGRP) • Proprietary to Cisco • Developed to replace RIP before OSPF • An advanced distance vector protocol – Includes aspects of both distance vector and link state protocols Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Dynamic Routing Makes the Internet • The Internet depends on dynamic routing for self-healing • Manual updating static routes would be impossible with so many routes Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Route Redistribution • A router takes routes it has learned by one method, say RIP or a statically set route, and announces those routes over another protocol such as OSPF Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Working with Routers Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Working with Routers • Simple physical installation – Home router • Give it power • Plug in connections – Business-class router • Insert it into a rack • Give it power • Plug in connections Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Connecting to Routers • Each router must be configured • Yost (or rollover) cable – One of the oldest methods for connecting to a router – A special serial connection – Almost unique to Cisco-brand routers Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.35 Cisco console cable Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Terminals and Consoles • Switches can also be configured • Managed devices – Routers and advanced switches • Plug the rollover cable into the console port on the router and a serial port on a PC – Use USB-to-serial adapter if no serial port is available Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.36 Console port Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Terminals and Consoles (cont’d.) • Use a terminal emulation program to talk to the router – Popular programs: PuTTY and HyperTerminal • Serial port settings – 9600 baud – 8 data bits – 1 stop bit – No parity Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.37 Configuring PuTTY Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Terminals and Consoles (cont’d.) • Once you are connected and running the terminal emulator – You will see the initial router prompt – Working with IOS commands • • • • Type enable and press ENTER The prompt changes to Router# IOS is complex Newer CISCO routers will lead you through the initial configuration for basic setup Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.38 Initial router prompt Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Web Access • Most routers have a built-in Web server – Easy to use and enables all functions • Router must have a built-in IP address – Use a laptop and a crossover cable – Set a static address for the computer to place the PC on the same network ID as the router – Connect to the router and type in the IP address Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.39 Default IP address Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.40 Entering the IP address Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.41 User name and password Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Network Management Software (NMS) • Advanced tool that describes, visualizes, and configures an entire network – Usually available as a Web site for network administrators • Types of NMS – Proprietary tools – Third-party tools Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.42 Cisco Network Assistant Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.43 OpenNMS Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Other Connection Methods • Most routers have more than one way to connect • Many home routers have a USB port and configuration software • More powerful routers may allow connection with Telnet protocol or newer Secure Shell (SSH) Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Basic Router Configuration • Must have at least two connections • Must properly configure every port on a router to talk to connected network IDs • Make sure the routing table sends packets to the intended destination Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.44 The setup Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) The Setup (Example in Figure 8.44) • Step 1: Set up the WAN side – The WAN side in a home or a small business router connects to an ISP – Get setup information from the ISP – Most home routers use DHCP on the WAN side and just need to be configured to use DHCP – Static IP address: follow instructions from the ISP Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.45 WAN router setup Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.46 Entering a static IP Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) The Setup (cont’d.) • Step 2: Set up the LAN – You have total control over the LAN side of the router – Choose a network ID from the private range – Assign the correct IP information to the LAN-side NIC Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.47 Setting up an IP address for LAN side Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) The Setup (cont’d.) • Step 3: Establish routes – The router will usually build a routing table based on information you provided – You may add more routes if needed – Use IOS command line on Cisco routers Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) The Setup (cont’d.) • Step 4 (optional): Configure a dynamic protocol – Dynamic routing protocols are tied to individual NICs – When you connect two routers together, make sure the NICs are configured to use the same dynamic routing protocol Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Document and Back Up • Document the steps completed to configure each router • Back up the configuration – Every router provides a backup method Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Troubleshooting Router Problems • Consider non-router issues first – Routers don’t fail very often • What is your router is supposed to do? – Does it just route traffic? – Does it also perform NAT? – Is routing failing, or is another function failing? • Know how to use basic tools to check the router: traceroute commands vary by OS Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) traceroute • Tells you when things are not working • Gives you an idea of where to look for a problem • Windows – tracert; UNIX/Linux – traceroute Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Other Tools • My traceroute (mtr) – Similar to traceroute – Dynamic, continually updates the route selected for monitoring – Linux tool • Window provides pathping – Computes the performance over a set time Copyright © 2015 by McGraw-Hill Education. All rights reserved. Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Fourth Edition (Exam N10-006) Figure 8.48 mtr in action Copyright © 2015 by McGraw-Hill Education. All rights reserved.