CCNA Guide to Cisco Networking Chapter 8: Routing Protocols and Network Address Translation

CCNA Guide to Cisco Networking 2 Objectives Understand the purpose and operation of network address translation (NAT) Configure static NAT, dynamic NAT, and dynamic NAT with overload Understand and configure port address translation (PAT) Differentiate between nonroutable, routed, and routing protocols Define Interior Gateway Protocols, Exterior Gateway Protocols, distance-vector routing protocols, and link-state routing protocols

CCNA Guide to Cisco Networking 3 Objectives (continued) Explain the concepts of count-to-infinity, split horizon, split horizon with poison reverse, and hold-down timers Describe, configure, and monitor the interior routing protocols RIP and IGRP Explain static routing and administrative distance Configure static routing and default routes

CCNA Guide to Cisco Networking 4 Network Address Translation Static NAT Dynamic NAT Port Address Translation Dynamic Nat with overload Overlapping

CCNA Guide to Cisco Networking 5 Network Address Translation (continued)

CCNA Guide to Cisco Networking 6 Network Address Translation (continued)

CCNA Guide to Cisco Networking 7 Network Address Translation (continued)

CCNA Guide to Cisco Networking 8 Configuring Network Address Translation Configure static NAT –Define static mapping between the inside address and the outside address –Define the router’s interfaces as inside or outside Basic NAT interface assignment –RouterA(config)# int fa 0/0 –RouterA(config-if)# ip nat inside –RouterA(config-if)# int serial 0/1 –RouterA(config-if)# ip nat outside

CCNA Guide to Cisco Networking 9 Configuring Dynamic NAT Configure a standard access control list to define what internal traffic will be translated Define a pool of addresses to be used for dynamic NAT allocation Link the access list to the NAT pool Define interfaces as either inside or outside

CCNA Guide to Cisco Networking 10 Configuring Dynamic NAT (continued) Dynamic NAT router configurations –RouterA(config)# access-list 1 permit –RouterA(config)# ip nat pool PoolExample netmask –RouterA(config)# ip nat inside source list 1 pool PoolExample –RouterA(config)# int fa 0/0 –RouterA(config-if)# ip nat inside –RouterA(config-if)# int serial 0/1 –RouterA(config-if)# ip nat outside

CCNA Guide to Cisco Networking 11 Configuring Port Address Translation To An Outside Interface Configure PAT router commands –Configure a standard access list to define what internal traffic will be translated –Link the access list to the interface to be used for PAT –Define interfaces as either inside or outside

CCNA Guide to Cisco Networking 12 Configuring Port Address Translation To An Outside Interface (continued) PAT router commands –RouterA(config)# access-list 1 permit –RouterA(config)# ip nat inside source list 1 interface serial 0/1 overload –RouterA(config)# interface serial 0/1 –RouterA(config-if)# ip nat outside –RouterA(config-if)# interface fa 0/0 –RouterA(config-if)# ip nat inside

CCNA Guide to Cisco Networking 13 Configuring Port Address Translation To An Outside Interface (continued)

CCNA Guide to Cisco Networking 14 Configuring Dynamic NAT With Overload Dynamic NAT with overload is a mixture of dynamic NAT and PAT –Dynamic NAT: Pool of inside addresses to a small pool of outside addresses –PAT: Same pool of inside addresses to an single outside address –PAT function becomes available when pool of outside addresses are all in use Use dynamic NAT and PAT configurations using the same pool of inside addresses

CCNA Guide to Cisco Networking 15 Nonroutable Protocols Peer-to-peer networks Microsoft Windows operation systems –NetBIOS Enhanced User Interface (NetBEUI) Very small Fast Efficient Cannot scale

CCNA Guide to Cisco Networking 16 Nonroutable Protocols (continued)

CCNA Guide to Cisco Networking 17 Routed Protocols Routed protocols Support networks Logical addresses Transmission Control Protocol/Internet Protocol (TCP/IP) Internetwork Packet Exchange/Sequence Packet Exchange (IPX/SPX)

CCNA Guide to Cisco Networking 18 Routed Protocols (continued)

CCNA Guide to Cisco Networking 19 Routing Protocols Path determination Routing tables –Metric –Autonomous system (AS) –Convergence Interior gateway protocols (IGP) –Routing information protocol (RIP) –Interior gateway routing protocol (IGRP) –Enhanced Interior gateway routing protocol (EIGRP) –Open shortest path first (OSPF) Exterior gateway protocols (EGP) –Border gateway protocol (BGP)

CCNA Guide to Cisco Networking 20 Routing Protocols (continued)

CCNA Guide to Cisco Networking 21 Routing Protocols (continued)

CCNA Guide to Cisco Networking 22 Two Types Of IGPs Distant vector and link-state Distant-vector –Routing by rumor –Routing loops –Count-to-infinity –Split horizon –Split horizon with poison reverse –Hold-down timers

CCNA Guide to Cisco Networking 23 Two Types Of IGPs (continued) Link-state –Link-state advertisements (LSA) –Shortest path first (SPF) algorithm –Link-state packets Common view of the topology –Floods or multicasts LSPs –Triggered updates

CCNA Guide to Cisco Networking 24 Two Types Of IGPs (continued)

CCNA Guide to Cisco Networking 25 Two Types Of IGPs (continued)

CCNA Guide to Cisco Networking 26 Two Types Of IGPs (continued)

CCNA Guide to Cisco Networking 27 Two Types Of IGPs (continued)

CCNA Guide to Cisco Networking 28 Two Types Of IGPs (continued)

CCNA Guide to Cisco Networking 29 Routing Information Protocol RIP has the following attributes –Distance-vector routing protocol –Maximum hop count of 15 –16 hops is considered infinity –Hop count is the only metric available for path selection –Broadcasts the entire routing table to neighbors every 30 seconds –Capable of load balancing –Easy to configure

CCNA Guide to Cisco Networking 30 Enabling RIP Routing

CCNA Guide to Cisco Networking 31 Enabling RIP Routing (continued)

CCNA Guide to Cisco Networking 32 Configuring RIP Routing For Each Major Network Design the network for the appropriate networks Configure interfaces to be gateways for networks Configure routing protocol In router mode establish networks to be advertised

CCNA Guide to Cisco Networking 33 Configuring RIP Routing For Each Major Network (continued)

CCNA Guide to Cisco Networking 34 Configuring RIP Routing For Each Major Network (continued)

CCNA Guide to Cisco Networking 35 “show ip protocol” and “debug ip rip” (continued)

CCNA Guide to Cisco Networking 36 “show ip protocol” and “debug ip rip” (continued)

CCNA Guide to Cisco Networking 37 “show ip route” Command

CCNA Guide to Cisco Networking 38 “show ip route” Command (continued)

CCNA Guide to Cisco Networking 39 “show ip route” Command (continued)

CCNA Guide to Cisco Networking 40 Interior Gateway Routing Protocol Proprietary distance-vector routing protocol Supports hop count of 255 –100 is the default hop count Supports up to four equal cost paths Routing table updates every 90 seconds

CCNA Guide to Cisco Networking 41 Interior Gateway Routing Protocol (continued) IGRP metrics –Hops: Number of routers between source and destination networks –Load: The load on a link in the path –Bandwidth: The speed of the link (default) –Reliability: Measures reliability with a scale of 0 to 255 –Delay: The delay on the medium (default) –MTU: The size of the datagram

CCNA Guide to Cisco Networking 42 Interior Gateway Routing Protocol (continued)

CCNA Guide to Cisco Networking 43 Interior Gateway Routing Protocol (continued)

CCNA Guide to Cisco Networking 44 Interior Gateway Routing Protocol (continued)

CCNA Guide to Cisco Networking 45 Interior Gateway Routing Protocol (continued)

CCNA Guide to Cisco Networking 46 Static Routing Adding static routes –Router(config)# ip route [destination network/destination ip address] [next hop ip address/forwarding interface] [administrative distance] –RouterD(config)# ip route Changing administrative distance –Default administrative distance of a static route is 0 if a forwarding interface is configured 1 if a next hop ip address is configured –Router(config)# ip route

CCNA Guide to Cisco Networking 47 Static Routing (continued)

CCNA Guide to Cisco Networking 48 Configuring A Default Route Routing protocols do not behave equally with default routes –Router(config)# ip route [next hop ip address/forwarding interface] [administrative distance] Router(config)# ip default-network [forwarding ip address]

CCNA Guide to Cisco Networking 49 Configuring A Default Route (continued)

CCNA Guide to Cisco Networking 50 Summary NAT is a technology that allows organizations to map valid external addresses to private or unregistered internal addresses This allows organizations to maintain a separation between the Internet and the intranet (internal network) while still providing access to the Internet Organizations can use NAT to allow many more people to access the Internet by sharing one or more valid public addresses PAT allows an organization to map more than one internal private IP address to a public IP address

CCNA Guide to Cisco Networking 51 Summary (continued) Protocols vary in their functions, some protocols are designed to be used in small networks without the need for Network layer addressing These protocols are described as nonroutable protocols, the most common nonroutable protocol is NetBEUI Other protocols were designed with the ability to move between multiple networks via Network layer addressing These protocols are routed protocols, the most common routed protocol suite is TCP/IP

CCNA Guide to Cisco Networking 52 Summary (continued) Protocols must be available that can find the best path throughout an internetwork and relay that information to routers Routing protocols serve this function on modern networks Routing protocols are classed in two major groups: Interior Gateway Protocols and Exterior Gateway Protocols Interior Gateway Protocols are routing protocols that function within a single autonomous system Exterior Gateway Protocols function as routing protocols between autonomous systems

CCNA Guide to Cisco Networking 53 Summary (continued) Interior routing protocols are further divided into distance-vector and link-state routing protocols These two types of Interior Gateway Protocols use very different methods to determine the best path in an internetwork Distance-vector protocols periodically broadcast entire routing tables to neighbor routers Link-state protocols multicast link updates to routers in their area upon startup and when network topology changes Two common distance-vector IGPs are the Routing Information Protocol and the Interior Gateway Routing Protocol

CCNA Guide to Cisco Networking 54 Summary (continued) RIP is an easy-to-configure routing protocol that uses hop count as its sole metric RIP has a hop count limit of 15 RIP uses split horizon, split horizon with poison reverse, and hold-down timers to help limit routing loops RIP can be used on Cisco and non-Cisco routers

CCNA Guide to Cisco Networking 55 Summary (continued) IGRP is also a distance-vector routing protocol with maximum hop count of 255 IGRP is not limited to using hop count as its sole metric IGRP can also use load, bandwidth, reliability, and delay when determining best path IGRP uses only bandwidth and delay by default IGRP is a Cisco proprietary protocol and can only be used on Cisco routers

CCNA Guide to Cisco Networking 56 Summary (continued) Static routes are used to conserve bandwidth and lower memory and CPU load on a router while still allowing for correct routing table creation Static routes give administrators control and flexibility in path selection in a network