BGP announcement

 Border Gateway Protocol (BGP) – A Fresh Look


Border Gateway Protocol (BGP) is an industry standard routing protocol created for the exchange of routing and reachability information over the Internet between large autonomous networks belonging to Service Providers and large Organizations. It is highly Scalable, Available, Secure and Robust. BGP is continuously evolving in tandem with internetworking technologies and architectures, cementing its place as the perfect partner for the next generation of networks and an enabler of Digital Transformation

Operation of BGP:

In the BGP world, the basic unit is the Autonomous System (AS) – a collection of IP networks running a common routing policy and controlled by one or more network operators under one administrative entity. Each AS consists of one or more BGP routers, configured manually to recognise its direct neighbour as a Peer. Once Peers establish connections with each other, they exchange the addresses of networks that they each can reach as well as the next hop to reach those networks. In short, they update each other’s routing tables with routes from their own local BGP routing table. Peers learn new routes through this exchange of information.

The BGP routing algorithm is intelligent and robust:

  1.  It can decide the most preferred path to a destination network. If it receives routing information to a destination network from more than one Peer, it does a comparison of the competing routes to decide the most preferable one and adds it to its routing table
  2. It can prevent rapidly changing routes from poisoning the routing tables. It does this with timers
  3.  It only allows information exchange between trusted routers
  4.  It can integrate routes learned from other routing protocols into the BGP routing table
  5. Why do you need to understand BGP?

With the rapid expansion of the Internet in the 1980’s, the need was felt for an enhanced exterior routing protocol to replace the incumbent Exterior Gateway Protocol (EGP) for communicating with routers outside the core network. BGP was formalized and established as the Internet’s exterior routing protocol of the future. Hence it is of interest primarily to administrators of Internet Service Providers (ISPs) or large private networks that connect to the Internet through multiple ISPs.

However now, in contrast to the past, BGP is becoming relevant to networks of all sizes. Illustrated below are a few scenarios that show how BGP can be utilised by smaller networks too.

Scenario 1: Reliable Internet Services

BGP is THE routing protocol of choice for the Internet. Opting for BGP will help ISPs maintain uniform and standard connections to other ISPs. Secondly, most large organisations are multi-homed to multiple ISPs; BGP is the de-facto routing protocol for such connections. Hence, Enterprises invariably use BGP to connect to their ISPs. Therefore, running BGP is an entry-level requirement for an ISP to gain a foothold in the Enterprise market. Technically speaking, though other routing protocols can be used, BGP has the highest control over route selection, flexibility, scalability and stability.

Scenario 2: Cost Effective VPN Services

ISPs and VPN Service Providers can use their existing IP backbone to provide VPN services to customers by using BGP/MPLS-Layer 3 VPNs. BGP distributes VPN routing information across the backbone and MPLS forwards VPN traffic to remote VPN sites. The stability and scalability of BGP allows Service Providers to offer value-added services like Quality of Service (QoS) and convergence of voice, video and data. For Enterprise Customers, BGP/MPLS-Layer 3 VPNs allows them to outsource routing information to Service Providers, resulting in cost savings and reduction of complexities.

Scenario 3: Stable Networks by Separating Interior and Exterior Routing

Although an Interior Gateway Protocol (IGP) can be used for distributing routing information to other Autonomous Systems, it is like using a screwdriver to hammer nails. Nothing stops you, but the screwdriver may get damaged or it might hurt the person. IGPs lack the scalability, route filtering and traffic engineering capabilities of an Exterior Gateway Protocol, like BGP. For example, inadequate filtering of routes at the AS edge can cause disastrous outages to internal as well as external networks. Hence it is highly recommended that ISPs, VPN Service Providers and Enterprises deploy the industry-standard Exterior Gateway Protocol, BGP.

Scenario 4: Resiliency against Denial-of-Service Attacks

An effective weapon against a Denial-of-Service (DoS) attack is the use of remote-triggered blackhole routing. BGP routers learn about remote networks and the next hop to reach them, from peers. Consequently, the BGP router’s routing table is a mixture of directly and non-directly connected networks. Now, BGP is the only routing protocol capable of propagating a non-directly connected next hop. This makes it a lot easier to kill DoS traffic because you need to define a blackhole only on a few strategic routers in your network.

Scenario 5: Quality of Service for mission-critical business traffic

BGP has a feature called QoS Policy Propagation. This feature allows the classification of traffic according to precedence. In other words, you can mark some traffic as more important than the others and give it a higher preference when it travels across the Internet or Enterprise network. BGP also supports Web Cache Communications Protocol, developed by Cisco Systems. The aim of this protocol is to optimize the use of network resources and lower response times.

Both these features result in a high-performance network, critical to ISPs and large Enterprises.

Scenario 6: Insurance against IPv4 Address Exhaustion

The IPv4 address space has exhausted many years ago at the top-level (IANA) as well as at the Regional Internet Registry (RIR) level. These organisations have implemented several post-exhaustion mitigations like, reclaiming unused addresses, creating markets in IP Addresses, transition mechanisms etc. As a result. the Internet is now a mix of IPv4 and IPv6 addresses, fragmented across the globe. Some RIRs have millions of reclaimed IPv4 addresses while others have a severe shortage. Added to this, ISPs and Enterprises are not yet ready to give up IPv4 addresses. In this scenario, BGP can help ISPs and Enterprises to advertise IPv4 addresses over IPv6 portions of the Internet, thus helping to maintain undisrupted global connectivity to customers.

How can Alnitech help you?

We can equip your business with the right Internetworking Technology that is crucial for facing the challenges posed by disruptive changes that are inevitable in the Internet space. Undisrupted Accessibility and Connectivity to your products and services are the 2 key ingredients for success in the Digital Economy

Our Services:

We Design and Build

  • BGP networks that give your business undisrupted global connectivity to your customers
  • Secure BGP networks that are resilient to Denial-of-Service Attacks
  • High Availability networks that connect to multiple Service Providers
  • High Speed networks for Mission-critical businesses and applications

and many more value-added services.

Why choose Alnitech:

  • Cost-effective tailor-made solutions, not one-size fits all
  • Partners to your business, not just a vendor
  • Qualified and experienced in-house Technical Support, not external 3rd party

Contact Us to discuss your specific need. We can help you choose the best BGP based solution for your organization.

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