routing protocol Flashcards
What is the primary function of a router, and how does it differ from a switch?
A router is a network device that connects multiple computer networks together and directs traffic between them. It determines the best path for data to travel from one network to another using routing protocols. Unlike a switch, which operates within a single network to forward frames based on MAC addresses, a router works at the network layer (Layer 3) to forward packets between different networks using IP addresses.
Explain the significance of routing protocols in networking.
Routing protocols are essential for enabling routers to dynamically share information about network topology, allowing them to determine the best path for data transmission. They facilitate network scalability, efficiency, and adaptability by ensuring that routers can make optimal forwarding decisions based on metrics like hop count, bandwidth, and delay.
Differentiate between Interior Gateway Protocols (IGPs) and Exterior Gateway Protocols (EGPs), providing examples of each.
IGPs are used within a single Autonomous System (AS) to facilitate communication between internal routers. Examples include:
RIP (Routing Information Protocol)
OSPF (Open Shortest Path First)
EIGRP (Enhanced Interior Gateway Routing Protocol)
EGPs are used between different Autonomous Systems to manage inter-network routing. The primary example is:
BGP (Border Gateway Protocol)
Describe the role of metrics in routing protocols and list three commonly used metrics.
Metrics help routers determine the best path for forwarding packets by evaluating different criteria. Common metrics include:
Hop Count: Measures the number of routers a packet must pass through.
Bandwidth: Represents the amount of data that can be transmitted over a link.
Delay: Measures the time taken for a packet to travel from source to destination.
What is convergence in routing, and why is it important?
Convergence occurs when all routers in a network have consistent and updated routing information. It is crucial for ensuring stable and efficient routing decisions, reducing downtime, and preventing routing loops.
How do Distance Vector and Link State routing protocols differ in their operation? Provide examples of each.
Distance Vector Routing Protocols determine the best path based on distance (hop count) and direction. Each router periodically sends its routing table to neighbors. Example: RIP, IGRP.
Link State Routing Protocols build a complete map of the network by sharing information about directly connected links, allowing routers to compute the best path independently. Example: OSPF, IS-IS.
What is Administrative Distance (AD), and how does it affect routing decisions?
Administrative Distance (AD) is a value assigned to different routing protocols to rank their trustworthiness. A lower AD value indicates a more reliable route. Routers prefer routes with the lowest AD when multiple routes to the same destination exist.
Compare and contrast RIP and OSPF in terms of their efficiency and scalability.
RIP (Routing Information Protocol)
Uses hop count as its metric (maximum of 15 hops).
Sends entire routing table updates periodically, consuming bandwidth.
Suitable for small networks but inefficient for large networks due to slow convergence.
OSPF (Open Shortest Path First)
Uses a link-state algorithm to build a complete topology of the network.
Only sends updates when changes occur, reducing bandwidth consumption.
Highly scalable and preferred for large, complex networks.
Explain how BGP differs from IGPs like RIP and OSPF.
BGP is an Exterior Gateway Protocol (EGP) used to route data between different Autonomous Systems (ASes) on the internet, whereas RIP and OSPF are Interior Gateway Protocols (IGPs) used within an AS. BGP determines routes based on various policies rather than just shortest path metrics and is essential for global internet routing.
What are the key steps in configuring a Cisco router?
Answer: Configuring a Cisco router involves several steps:
Access the Router: Connect using a console cable and access the CLI.
Enter Global Configuration Mode: enable → configure terminal.
Assign IP Addresses: Configure interfaces using interface <interface_name> and ip address <IP> <subnet_mask>.
Enable Routing Protocols: Example:
router rip
network <network_address>
Set Administrative Distance (Optional): distance <value>.
Save Configuration: write memory or copy running-config startup-config.</value></network_address></subnet_mask></IP></interface_name>
Distinguish between Privilege Mode and Global Configuration Mode on a Cisco Router.
Privilege Mode (enable mode): Allows access to show commands and troubleshooting but not configuration changes.
Global Configuration Mode (configure terminal): Enables modifications to the router’s settings, including interface configurations and routing protocols.
Describe the process of configuring a Cisco switch.
Access the switch via console.
Enter Privilege Mode: enable.
Enter Global Configuration Mode: configure terminal.
Assign VLANs and ports using interface commands.
Configure trunking if needed with switchport mode trunk.
Save settings using write memory.
Why is OSPF preferred over RIP in large networks?
OSPF is preferred because it:
Uses a hierarchical structure (areas) to reduce routing table size.
Converges faster due to link-state advertisements.
Supports advanced features like authentication and load balancing.
What problem does the Split Horizon rule solve in Distance Vector Routing Protocols?
The Split Horizon rule prevents routing loops by disallowing routers from advertising a route back to the interface it was learned from. This stops incorrect routing updates from being propagated in the network.
How does EIGRP improve upon RIP and OSPF?
EIGRP combines the best features of Distance Vector and Link State protocols:
Uses the Diffusing Update Algorithm (DUAL) for fast convergence.
Supports unequal-cost load balancing.
Reduces overhead by sending updates only when topology changes.
