Introduction To Networking Routing Protocols

RIP RIP (Routing Information Protocol) is one of the earliest routing protocols RIP used for routing within an autonomous system (e.g., an IGP) RIP is a distance vector routing protocol, meaning every router shares its entire routing table with every neighbor at every routing update RIP uses hop count as the metric RIP networks are limited in size to a maximum of 15 hops between any two networks. A network with a hop count of 16 indicates an unreachable network RIP v1 is a classful protocol (Does not support Variable Length Subnet Masks, VLSM); RIP v2 is a classless protocol (supports VLSM) RIP is best suited for small private networks

EIGPR Enhanced Interior Gateway Routing Protocol (EIGRP) is an IGP protocol developed by Cisco EIGRP is considered a hybrid protocol, or an advanced distance vector routing protocol since it uses distance vector with some extra features to increase reliability EIGRP uses a complex formula for the metric, taking into account bandwidth, load, delay and reliability, as well as administrator set values EIGRP is a classless protocol so it supports VLSM EIGRP is best suited for medium to large private networks

OSPF Open Shortest Path First (OSPF) is an IGP routing protocol OSPF is a link-state routing protocol, so each router floods the network with its local networks when it is time to update OSPF uses relative link cost based on bandwidth for the metric OSPF is a classless protocol, supporting VLSM OSPF divides a large network into areas OSPF is best suited for large private networks

OSPF Areas Each autonomous system requires an area 0 that identifies the network backbone All areas must connect to area 0, either directly or indirectly through another area Routes between areas must pass through area 0 Routers are classified into one of three types Internal routers share routes within an area area border routers share routes between areas autonomous system boundary routers share routes outside of the AS A router is the boundary between one area and another area

IS-IS Intermediate System to Intermediate System (IS-IS) is an IGP routing protocol IS-IS is a link-state routing protocol, so each router floods the network with its local networks when it is time to update IS-IS uses relative link values defined by network admins for the metric IS-IS is a classless protocol, supporting VLSM IS-IS divides a large network into areas like OSPF IS-IS is best suited for large private networks; it supports larger networks than OSPF. IS-IS is typically used within an ISP and easily supports IPv6 routing

IS-IS Areas While IS-IS divides a large network into areas, there is no area 0 requirement, and IS-IS provides greater flexibility than OSPF for creating and connecting areas Routers are classified into one of three types: L1 routers share routes within an area L2 routers share routes between areas L1/L2 router can share routes with both L1 and L2 routers L1 routers will only share information between L1 routers, and L2 routers will only share information betweens L2 routers, which is why L1/L2 routers are necessary A network link is the boundary between one area and another area.

BGP Border Gateway Protocol (BGP) is an exterior gateway protocol (EGP) used for routing between autonomous systems BGP is an advanced distance vector protocol (also sometimes called a path vector protocol) and is classless BGP uses paths, rules, and policies instead of a metric for making routing decisions Internal BGP (iBGP) is used within an autonomous system; External BGP (eBGP) is used between autonomous systems. BGP is the protocol used on the Internet; ISPs use BGP to identify routes between autonomous systems. Very large networks can use BGP internally, but typically share routes on the Internet only if the AS has two (or more) connections to the Internet through different ISPs

Commands to Set Up Routing To set up a static route Ip route [IP ADDRESS] [SUBNET MASK] [PHYSICAL PORT] To set up OSPF Router ospf [PROCESS NUMBER] The Process Number is just an id number for the router, and has no bearing on routing Followed by Network [IP ADDRESS] [WILDCARD MASK] area [AREA NUMBER] A wildcard mask is basically an inverse Subnet mask For Example IP Route 100.100.100.0 255.255.255.0 s0/0/0 Router ospf 100 Network 10.10.10.0 0.0.0.255 area 0