BGP Basics for Businesses Considering Their Own ASN

BGP Basics for Businesses Considering Their Own ASN

For many businesses, Internet connectivity starts with a simple setup: connect servers to an ISP, receive IP addresses, and let the provider handle routing.

That model works well for many organizations. But as a company grows, it may need multiple Internet providers, its own IP address space, greater control over routing, or improved network resilience. This is where BGP and an Autonomous System Number (ASN) become important.

Before requesting an ASN, however, businesses should understand what BGP actually does, why an ASN is needed, and what operating a BGP network involves.

What Is BGP?

BGP, or Border Gateway Protocol, is the routing protocol used to exchange reachability information between different autonomous systems on the Internet.

An Autonomous System is a collection of IP networks operating under a clearly defined routing policy. Each AS is identified by an ASN. APNIC describes the ASN as identifying a BGP-speaking, self-managed routing entity with a single routing policy.

In simple terms, BGP helps different networks tell each other:

“These IP networks are reachable through me.”

Your ISP uses BGP to exchange routes with other networks, and large enterprises, cloud providers, hosting companies, telecom operators, and data centers may operate BGP themselves.

What Is an ASN?

An Autonomous System Number is a unique identifier assigned to an Autonomous System.

Think of an ASN as the identity of a network in the global BGP routing system.

Having an ASN does not automatically give a business IP addresses, bandwidth, or Internet connectivity. These are separate resources and services.

An organization considering its own ASN should therefore think about three related but distinct components:

ASN + IP resources + BGP connectivity

All three may be relevant to an organization building an independently routed network.

Why Would a Business Need Its Own ASN?

The most common reason is the need to operate its own external routing policy, particularly when connecting to multiple upstream networks.

For example, imagine a company connected to two different Internet providers:

Business Network → ISP A

Business Network → ISP B

With an appropriately designed BGP setup, the organization can advertise its routes through both connections and influence how traffic enters and leaves its network.

This is commonly referred to as multihoming.

Current RIPE guidance states that an ASN is associated with a clearly defined routing policy and that, under its current policy, a network must be multihomed and have a unique routing policy to qualify for an ASN.

The relevant Regional Internet Registry policy should always be checked before applying because requirements can change.

How Does BGP Multihoming Work?

In a basic multihomed design, your network establishes BGP sessions with two or more upstream providers.

Each provider exchanges routing information with your network.

BGP can then be used to influence:

• Which provider receives outbound traffic
• Which provider is preferred for certain routes
• How incoming traffic reaches your network
• Which paths should be used when another connection fails

For example, an organization may prefer ISP A for normal traffic while keeping ISP B available as an alternate path.

If ISP A becomes unavailable, routing can converge toward the available path through ISP B.

The exact behavior depends on the BGP configuration and policies applied by the network.

BGP Does Not Automatically Mean Better Performance

It is important not to treat BGP as a magic performance solution.

BGP provides routing control. It does not automatically make an Internet connection faster.

Actual performance depends on factors such as:

• Upstream providers
• Physical network paths
• Peering arrangements
• Internet exchange connectivity
• Transit quality
• Latency
• Congestion
• Routing policy

A carefully designed BGP network can provide greater control and redundancy, but the underlying connectivity still matters.

What Does a Business Need to Operate BGP?

Running BGP requires more than simply obtaining an ASN.

A business generally needs suitable network equipment, upstream connectivity, IP resources, routing policies, monitoring, and technical expertise.

Depending on the architecture, this may involve:

• BGP-capable routers
• Two or more upstream providers
• Public IP address space
• ASN
• BGP sessions
• Route filtering
• Prefix management
• Monitoring and alerting
• Redundant network infrastructure

Security is also important. Incorrect route advertisements can cause outages or routing problems, so businesses should implement appropriate prefix filters, route policies, authentication where applicable, and operational controls.

ASN and IP Addresses Are Different

This distinction causes confusion for many businesses.

An ASN identifies your autonomous system, while an IP address prefix identifies the network addresses you are announcing or using.

Obtaining an ASN does not automatically mean that you receive a large IPv4 or IPv6 allocation.

The relevant Internet Registry determines the policies and procedures for numbering resources.

For Indian organizations, APNIC is the Regional Internet Registry responsible for the Asia Pacific region, so businesses should review the applicable APNIC policies and eligibility requirements before beginning an application.

When Should a Business Consider Its Own ASN?

An ASN becomes more relevant when a business has a genuine routing requirement.

Examples can include:

• Multiple Internet providers
• Data center multihoming
• Hosting or cloud infrastructure
• Internet service operations
• Independent routing requirements
• Network resilience projects
• Public IP infrastructure that needs provider-independent routing

A business with one ISP and a straightforward network may not need to operate BGP itself.

The objective should be to solve a specific networking requirement rather than obtain an ASN simply because the organization is growing.

What Should You Plan Before Applying?

Before pursuing an ASN, document your intended network architecture.

Start with:

1. Upstream connectivity: Which providers will carry your traffic?

2. IP resources: What IPv4 and IPv6 prefixes will you use?

3. Routing policy: Which routes will you advertise and prefer?

4. Redundancy: What happens if one upstream connection fails?

5. Hardware: Do your routers support the required BGP features?

6. Operations: Who will monitor routes and respond to incidents?

7. Security: How will you prevent accidental or unauthorized route advertisements?

Having these answers ready makes the deployment process considerably easier.

Final Thoughts

BGP is one of the technologies that makes the Internet’s interconnected routing system work. For businesses, its biggest value is routing control and the ability to build independently managed external connectivity.

An ASN can be an important part of that architecture, but it should not be viewed as a standalone product.

Businesses considering their own ASN should first establish why they need independent routing, determine their IP requirements, evaluate upstream providers, and understand the applicable Regional Internet Registry policies.

When the business genuinely needs multihoming or an independent routing policy, understanding BGP fundamentals becomes essential before moving into production.

Read More: DDoS Protection for Networks

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FAQs

What is BGP in simple terms?

BGP is a routing protocol that allows different autonomous systems to exchange information about network reachability. It helps networks determine how traffic can travel between different parts of the Internet.

What is an ASN used for?

An ASN uniquely identifies an Autonomous System in inter-domain routing. It is used with BGP when a network exchanges routing information with other autonomous systems.

Does every business need its own ASN?

No. Businesses using a simple single-ISP network generally do not need to operate their own ASN. An ASN becomes relevant when the organization has a legitimate need for its own external routing policy, such as certain multihomed network architectures.

Does an ASN provide Internet connectivity?

No. An ASN is an identifier, not an Internet connection. A business still needs appropriate upstream connectivity and network infrastructure to exchange traffic.

Can I use BGP with two ISPs?

Yes. Multihoming with two or more upstream providers is a common reason organizations operate BGP. The network can use BGP policies to influence route selection and maintain alternate connectivity.

Is BGP difficult to manage?

BGP is more complex than basic static routing or common internal routing configurations. Incorrect configuration can cause routing problems, so businesses should have appropriately skilled network engineers or work with a qualified network provider.

Does having an ASN guarantee better uptime?

No. An ASN by itself does not provide redundancy. Higher availability depends on the complete architecture, including multiple upstream connections, diverse network paths, appropriate routing policies, redundant equipment, monitoring, and operational procedures.

Is an ASN the same as an IP address block?

No. An ASN identifies an autonomous system, while an IP prefix represents a range of network addresses. They are separate numbering resources and may have different eligibility and allocation requirements.