1. Introduction To Networking
Routing Protocols

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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.

8. 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

9. 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 s0/0/0
Router ospf 100
Network area 0