Border Gateway Protocol

BGP's primary function is to ensure that packets of information are forwarded in the most suitable path on the internet.

The current BGP version 4 was released in 2006.

The key components of the BGP algorithm are the routing table, routing policy, and BGP speakers.

When a data packet needs to be transmitted, the origin router sends a request to its BGP peers, they respond with their best paths. The origin router uses the BGP algorithm to select the best path and forwards the packet along that route.

BGP manages how packets are routed across the internet by exchanging routing and reachability information between edge routers. It directs packets between autonomous systems, networks operated by different organisations.

The three types of RIBs are Adj-RIBs-In (stores route information received), Loc-RIB (keeps the best paths for outgoing routing), and Adj-RIBs-Out (has routes to be advertised).

EBGP connects different autonomous systems and its updates are exchanged between routers in different AS. IBGP is used within an autonomous system and its updates are exchanged between routers in the same AS.

BGP is commonly used for inter-domain routing (exchanging routing information amongst distinct autonomous systems) and in large corporate networks for internal load balancing and maintaining redundant internet connections.

The Border Gateway Protocol plays a critical role in network security by routing and rerouting data packets, protecting against data theft. Measures to secure BGP include the Resource Public Key Infrastructure that validates route announcements, and BGPsec, a security layer addition.

BGP has significant real-world applications in load balancing, inter-domain routing and providing redundancy. It helps maintain efficient data flow during network congestion by rerouting excess traffic and assures accessibility even if one internet connection fails.

When BGP fails, it can lead to inefficient routing and potentially 'routing loops', where data packets circulate without reaching their destination. Usually, these outcomes occur due to BGP configuration errors or faulty hardware, necessitating fast recovery through rectification or hardware replacement.

Risks in BGP operations can be mitigated through periodic auditing of BGP configurations, security protocol deployment, and workforce education. Resources like RPKI validate BGP route announcements, while BGPsec encrypts BGP messages to authenticate data and ensure its integrity.

Border Gateway Protocol (BGP) is a standardized exterior gateway protocol that routes information across the internet, specifically across autonomous systems. It is a path vector protocol ensuring accurate and efficient data delivery.

An autonomous system is a network or collection of networks that are under the control of a single entity, such as an Internet Service Provider (ISP).

Policies in Border Gateway Protocol are used for regulating and optimising network communication. They manage and provide flexibility to the intricacies of paths that data can traverse on the internet.

BGP manages how packets are routed across the internet through sharing information between edge routers.

The three fundamental processes are: establishment of TCP connections, exchange of BGP messages, and implementation of BGP policies.

BGP achieves this by controlling routing information, distributing network reachability information, selecting paths to external networks based on routing policies, and ensuring loop-free inter-domain routing.

BGP operates by communicating information about reachable networks across internet service providers (ISPs). Each ISP operates an autonomous system and uses BGP to share information about the reachability of its directly connected networks. This info is then propagated across the internet, shaping routing tables used by routers to guide data packets to their destined IP address.

ISPs utilise BGP to orchestrate pathways data packets follow, enabling them to enforce policy controls and make decisions based on business and cost considerations. They can selectively prefer certain paths over others, turning BGP into a mechanism for business-driven routing, not just shortest-path routing.

AS_PATH is a sequence of Autonomous System (AS) numbers included in each network advertisement from one BGP speaker to another. It shows the trail of autonomous systems to be traversed to reach a network, helping to avoid routing loops and assist in path selection. Networks prefer shorter AS_PATHs to ensure better network performance.

EBGP is used specifically for routing between different autonomous systems (ASes). It exchanges network reachability information with systems in different networks to facilitate data packet transmission across distinct autonomous systems.

MED is a BGP attribute that provides a hint about the preferred path into an autonomous system (AS). Routes with lower MED values are preferred, assisting in determining the best path for a data packet.

In large-scale network environments, EBGP often facilitates peering between Internet Service Providers (ISPs). Each provider, identified as a separate AS, uses EBGP to exchange route information, building comprehensive routing tables for efficient data packet transmission.

The path-vector algorithm is the core of BGP that functions like a distance-vector algorithm but avoids count-to-infinity problem. Instead of sharing just costs, it shares paths, allowing routers to make informed decisions on routing packets based on cost and specific path the packet would take.

The steps include importing routing information from peers into the local BGP table, calculating a degree of preference for each route, selecting the best path based on the highest preference, and then advertising this path to other BGP speakers in the network.

The efficiency of BGP includes supporting a large number of prefixes, offering a high degree of route control, enabling policy-based routing, delivering reliable routing information, and increasing resiliency and redundancy. Its preference for security and stability over speed is a key attribute.

BGP's central role is in creating a cohesive set of rules that data packets follow in their journey from one part of the internet to another.

An autonomous system (AS) is a network or group of networks that share exactly the same routing policies.

Key features of BGP include scalability, route aggregation, policy-based routing, and a loop prevention mechanism.

BGP was designed to be exceptionally robust and high in fault tolerance, meaning it can withstand network problems and recover rapidly without causing significant disruption to data flow.

The primary purpose of Border Gateway Protocol (BGP) is to direct data packets through appropriate routes across the internet, serving as the postal service of the internet.

The process starts with an internet router announcing its IP prefixes or routes to its neighbours. The neighbours add their own autonomous system number (ASN) to the route and propagate it. This propagation continues throughout the network, enabling routers to learn the paths to all network segments.

A BGP Speaker sends a request to start a peering session with other speakers, forming a TCP connection between them. Upon successful establishment of this connection, BGP Speakers exchange messages to form a BGP Peer relationship.

Each BGP speaker running on a router contains a unique algorithm that determines the best route. Each router builds a database with available paths and their characteristics, known as BGP Attributes, using these attributes to compare routing paths and decide on the most preferred one.

BGP is responsible for routing data through numerous routers and servers to its ultimate destination. It supports policy-based routing, offering control over routing decisions.

BGP ensures secure and efficient route for data packets to travel between different offices of the corporation, while also considering congestion and server availability for data routing.

EBGP ensures efficient and secure data exchange between different autonomous systems or routers maintained by separate entities. It applies policy-based routing to direct traffic along the most efficient path.

EBGP analyses path attributes and applies policy-based routing. It directs traffic along the most efficient or preferred path, preventing data packets from getting lost or looped endlessly.