IP Routing Introduction and Routing Mechanism:
IP routing – sending data packets from one network to another through routers. It is routers that examine destination IP address, determine next- hop address to forward a packet. Remote router- IP address of router used to reach that network. Outgoing interface. Populating routing table- directly connected subnets, static routing, default, dynamic routing.
Directly Connected Interface – routes local to router-one or more networks or subnets.- easily recognizable – traffic directed to these networks- can be forwarded without any help from routing protocols. Static routing- routes to destination manually entered by network administrators in router’s route table, don’t adjust to changes in the network. Default gateway – the router that hosts use to communicate with other hosts – remote networks. Why use Default Gateway?
Default routing – stub networks. Networks having only one output interface, all data going through a single exit. Instead of having many static routes connecting to remote networks – single output interface- single default is configured to match all routes.
Dynamic Routing – optimal data routing, enables routes to select paths according to real-time logical network changes. Routing protocol responsible for the creation, maintenance, update of a dynamic routing table. Static routing- all routing jobs have done manually by a network administrator.
Types of dynamic routing – Routing Information Protocol (RIP) and Open Shortest Path First (OSPF). Dynamic –least expensive routing process. It delivers and receives routing messages on router interfaces, information shared with other routers, swap routing information with others routes to find data about remote networks. Dynamic routing – security, RAM, CPU usage.
Routing Table – routers maintain routing table stored in RAM- it is used to determine the path to the destination. Entries- network destination, network subnet mask-specifies range of IP addresses
Routing metrics:
a unit calculated by a routing algorithm for section or rejection of a routing path for transfer of data/traffic. Used for finding out the optimal route for sending network traffic. Each different route has a metric, calculated using many different techniques, methods of routing algos in use- Hop Count- number of routers data has to pass through to reach destination, Path Reliability-amount of network downtime, Delay-due to distance or congestion on route, Path Speed, Load, Reliability, ticks-measurement of delay –tick 1/18 a sec- used as part of routing protocol IPX RIP, Maximum Transmission Unit- largest unit size permitted to be send on all routes from source to destination, cost, Bandwidth-throughput out in bits per second, latency, maximum transmission unit.
Different protocols use different calculations to arrive at an optimal route-EIGRP uses complex equations, EIGRP- bandwidth, delay, reliability, load. OSPF metric value – OSPF Cost Value- accumulated cost to send packets from source network to destination. Cost of interface inversely proportional to the bandwidth of that interface- higher bandwidth, lower cost, low bandwidth, higher cost.
If a router finds different paths with the same administrative distance value and metric value to a destination, load balance can happen. For most routing protocols- route with least metric is taken as the best route.
A protocol is a set of procedures that must be followed when transmitting or receiving data. It defines format, timing, sequence, error checking on the network. There are hundreds of protocols in use.
Routing metrics – different parameters, operational environments- cost calculation for a given path. Bellman-Ford Algorithm- for adding total hops (Intermediary routers), involved in reaching a destination. Path reliability, load, speed, latency, packet loss- inputs for calculating path cost in modern routing protocols.
Comparing routing metrics – routes have same Administrative Distance-trust worthiness of routing info received.
Static and Dynamic Routing –
Differences between Static and Dynamic Routing. Static for small networks- a college campus with a predictable number of users. Static –minimum bandwidth usage, laborious task to set up, tedious to maintain and troubleshoot. Dynamic for large networks that keep changing, respond to change, easier to maintain, better for growth.
Static routing: configure d manually typing global configuration mode command IP route- DESTINATION_NETWORK SUBNET_MASK NEX_HOP_IP_ADDRESS. Usually used in smaller networks – scalability reasons.
Packet Tracer: Simulation software – simulates router, switch, networking equipments-helps reduce the cost of training. Helps students in getting hands-on-practice on CISCO devices. Help learners create own self-evaluated assignments to demonstrate networking concepts. Learners can learn to configure routers, switches from command line Packet Tracer provides visual drag and drop problem using networking devices.
-Static Routing- administrative distance- It is used for priority setting. Different routes in a destination network can be assigned different weights. Routes with same weight share traffic, Changing Administrative Distance in static routes.
-Static and Dynamic Routing with protocols: Static – routing tables set by a network administrator. Dynamic Routing Protocols- dynamically discover network destinations. Continuously change network status updates between each other as broadcast or multicast- Routing Information Protocol (RIP), Enhanced Interior Gateway Routing Protocol (EIGRP), Open Shortest Path First (OSPF).
Types of protocols- Distance –
Vector Routing Protocols – use simple algorithms to find out cumulative distance value between routers based on hop count- RIP, IGRP.
Link-State Routing Protocols– using sophisticated algorithms which maintain a complex database of internetwork topology. (Eg. OSPF), Intermediate System to Intermediate System (IS-IS).
Hybrid Routing Protocols– use combination of distance-vector, link-state methods that try to incorporate the advantages of both, minimize disadvantages- EIGRP, RIP 2.
Hybrid has advantages of both distance vector and link state routing protocols, merges them into a new protocol.
EIGRP has characteristics of both Distance Vector, Link State Routing protocols. EIGRP –hybrid routing protocol- doesn’t send Link State Advertising packets as OSPF. Sends traditional distance vector updates containing information about networks plus the cost of reaching them. Routing protocols distribute routing information to all routers in a network. Each router knows about all other routers in a connected network. It enables data packets to reach a destination faster.
IP Routing Requirements
The IP Routing and Routing Protocols course can be learned by anyone with a basic knowledge of computers, computer networking basics, internet and a passion to learn.
Why learn IP Routing and Routing Protocol?
Today business and technological success depend on how data is transmitted fast along networks. IP routing enables data to be transmitted via routers choosing the optimal path to a destination. It is useful for network engineers, network administrators, VOIP engineers, switching, router engineers tobetter their job prospects and career growth. The course enables learners to understand concept s related to routers, how to configure various protocols with a simulator, understand both static and dynamic routing among others.
