ASN Use Cases: 8 Real Examples and When You Need One

A network needs its own ASN (Autonomous System Number) when it announces its own IP prefixes over BGP to more than one neighboring network. ISPs, hosting providers, CDNs, Internet exchanges, mobile operators, research networks and multihomed companies all hold one, and so can an individual with two upstreams. In the RIPE region the test is ripe-679: "A network must be multihomed in order to qualify for an AS Number." A single-homed network or a lab can run a private ASN instead.

The RIPE NCC registered 2,175 new ASNs between 1 January and 24 September 2026 and 2,734 in the twelve months to that date, all of them 32-bit (data snapshot of 24 September 2026, series in State of RIPE ASNs 2026). This page walks through who those numbers go to, with real AS numbers, and what an ASN is if you need the definition first.

Use Case 1: Internet Service Providers (ISPs)

Internet Service Providers are the most common holders of ASNs.

Why ISPs Need ASNs

An ISP announces its own allocations, sets its own routing policy and buys transit from more than one upstream. The ASN is what lets it peer at Internet exchanges and sell BGP transit to its own customers. Without one, its address space would be announced under a provider's number and would move with that provider.

Real-World ISP Examples

Regional ISP Example:

A regional ISP serving enterprise customers in Europe holds AS64500 (example). They:

Announce their IPv4 /20 and IPv6 /32 allocations
Maintain transit connections with two Tier-1 providers (AS174 Cogent and AS3356 Lumen)
Peer at multiple Internet Exchange Points (AMS-IX, DE-CIX, LINX)
Implement BGP communities for traffic engineering
Provide BGP transit services to business customers

Major ISP ASN Examples:

AT&T: AS7018, one of the largest US carriers
Verizon: AS701, major North American ISP and Tier-1 network
Orange: AS5511, major European telecommunications provider
Telxius (Telefónica group): AS12956, international carrier of the Telefónica group

Look up any of these numbers with our ASN lookup tool to see the prefixes each one announces and its neighbors.

When ISPs Need Multiple ASNs

Large ISPs often hold multiple ASNs for:

Geographic separation: Different ASNs for different regions or countries
Service differentiation: Separate ASNs for consumer vs. enterprise services
Acquired companies: Maintaining ASNs from acquired businesses during integration
Technical isolation: Separating different network architectures or technologies

Use Case 2: Hosting Providers and Data Centers

Hosting providers and data center operators commonly need ASNs to provide reliable, high-performance services to customers.

Why Hosting Providers Need ASNs

A hosting provider assigns addresses to customer servers and needs those addresses reachable when one transit link fails, so it multihomes and announces the space from its own ASN. The same number lets it announce customer-held prefixes, offer BGP sessions to enterprise tenants and run anycast for distributed services.

Real-World Hosting Provider Examples

Cloud Hosting Provider Example:

A European cloud hosting provider (AS64502, example) operates data centers in Amsterdam, Frankfurt, and London. Their ASN enables:

Announcing customer IPv4 /24 allocations and IPv6 /48 assignments
Multi-homing through three transit providers so one failure does not take the site down
Peering at local IXPs to reduce latency and costs
Offering BGP services to enterprise customers
Implementing anycast for distributed services

Major Hosting Provider ASN Examples:

Amazon Web Services: AS16509 (primary), the largest public cloud
Google Cloud: AS15169 (primary), global cloud infrastructure
Microsoft Azure: AS8075 (primary), major cloud services provider
DigitalOcean: AS14061, cloud hosting focused on developers
OVHcloud: AS16276, European hosting and cloud provider

Specialized Hosting Use Cases

Anycast CDN Implementation:

A hosting provider implements anycast for DDoS protection:
- Same /24 IPv4 prefix announced from AS64500 in multiple locations
- Locations: Amsterdam (AMS-IX), Frankfurt (DE-CIX), Paris (France-IX)
- Traffic automatically routes to nearest PoP
- DDoS attacks distributed across multiple locations

Use Case 3: Enterprise Networks

Enterprises obtain ASNs when their connectivity must survive the loss of one provider.

Why Enterprises Need ASNs

An enterprise gets an ASN to keep its connectivity when a provider fails and to change providers without renumbering. Two upstreams, its own address space and its own number give it control over failover and over how inbound traffic reaches its sites.

Real-World Enterprise Examples

Financial Services Company:

A multinational bank (AS64501, example) uses their ASN for:

Connecting headquarters and trading floors to multiple ISPs
Redundant connectivity for business-critical applications
IPv4 space bought on the transfer market and an IPv6 PI /48
Precise control over inbound traffic routing
Compliance with financial industry resilience requirements

Enterprise Multi-homing Configuration:

Enterprise Network: AS64501
Primary Transit: AS3356 (Lumen) - 1 Gbps
Secondary Transit: AS1299 (Arelion) - 1 Gbps
IP Space: 203.0.113.0/24 (IPv4), 2001:db8:100::/48 (IPv6 PI)

BGP Configuration:
- Receive full tables (or a default route) from both providers
- Announce only your own prefixes to each provider
- Use communities for traffic engineering
- Failover follows BGP session state

Enterprise Sectors Commonly Using ASNs:

Financial services (banks, trading firms, insurance)
Healthcare organizations (hospitals, medical networks)
Technology companies with critical online services
E-commerce platforms requiring high availability
Government agencies with security requirements

When Enterprises DON'T Need ASNs

Many enterprises don't need ASNs because:

Single ISP connection is sufficient for their needs
Provider-managed redundancy is adequate
The fees and the operating effort exceed what the redundancy is worth
Lack of technical expertise to manage BGP routing
Business criticality doesn't justify complexity

Bringing Your Own Addresses to a Cloud (BYOIP)

A company that holds its own address space can announce it from AWS, Azure or Google Cloud instead of, or alongside, its own routers. AWS accepts ranges from ARIN, the RIPE NCC and APNIC only, registered to a business or institutional entity and not to an individual, at /24 for IPv4 and /48 for advertised IPv6, with a ROA authorizing AS16509 and AS14618; your own ASN is optional there (BYOASN). Azure announces under AS8075 and Google Cloud's ROA ASN is 396982 (Premium Tier), so the prerequisite is address space registered to you, in the RIPE region a PI /48, more than an ASN. Per-cloud steps: BYOIP Explained: Bringing Your Own IP Addresses to AWS, Azure and GCP.

Use Case 4: Content Delivery Networks (CDNs)

CDNs use ASNs to announce the same content from many locations.

Why CDNs Need ASNs

A CDN announces the same prefixes from many points of presence, so users reach the nearest one. That needs an ASN of its own, direct peering with eyeball networks and control over how each announcement is steered.

Real-World CDN Examples

Major CDN ASN Examples:

Cloudflare: AS13335, global CDN and security provider present in 348 cities (Cloudflare, September 2026)
Akamai: AS20940 (and others), one of the largest CDN providers globally
Fastly: AS54113, edge cloud platform and CDN
CloudFront (Amazon): uses AWS ASNs including AS16509

CDN Anycast Implementation:

Cloudflare's AS13335 shows how an anycast CDN is built:

Same IP prefixes announced from 348 cities (Cloudflare, September 2026)
Traffic automatically routes to nearest PoP based on BGP routing
DDoS mitigation through distributed infrastructure
Cloudflare says 95% of Internet users are within 50 ms of one of its data centers (Cloudflare network page)

Anycast Configuration Example

CDN Network: AS64503
Service IP: 203.0.113.0/24 (anycast prefix)

PoP Locations:
- New York: Announces 203.0.113.0/24 to AS3356, AS6939
- London: Announces 203.0.113.0/24 to AS1299, peering at LINX
- Tokyo: Announces 203.0.113.0/24 to AS2914, peering at JPIX
- Sydney: Announces 203.0.113.0/24 to AS4826, peering at Equinix Sydney

Result: Users automatically connect to geographically nearest PoP

Use Case 5: Internet Exchange Points (IXPs)

Internet Exchange Points let networks interconnect directly over a shared switching fabric.

Why IXPs Have ASNs

An exchange holds an ASN for its route servers, which take one BGP session per member and redistribute routes among participants so members do not have to configure a full mesh. The number also represents the exchange as a neutral party in the routing table.

Real-World IXP Examples

Major IXP ASN Examples:

AMS-IX (Amsterdam): AS1200, one of the world's largest exchanges
DE-CIX (Frankfurt): AS6695, route servers of the Frankfurt exchange
LINX (London): AS5459, major London Internet exchange
Equinix (Multiple locations): AS24115, global IXP operator

IXP Route Server Function:

Most IXPs operate route servers that:

Accept BGP sessions from IXP members
Redistribute routes among participants
Eliminate need for full-mesh BGP peering
Filter invalid routes and provide security
Simplify peering configuration for members

Use Case 6: Mobile Network Operators

Mobile carriers use ASNs for their data networks and mobile Internet services.

Why Mobile Operators Need ASNs

A mobile operator announces the address space behind its packet core, connects roaming partners and carries subscriber traffic to the Internet from its own number.

Examples of Mobile Operator ASNs:

Vodafone: AS1273 (and multiple regional ASNs)
T-Mobile: AS21928 (US), various international ASNs
Orange Mobile: Multiple ASNs across operating regions
China Mobile: AS9808 (CMNET)

Mobile-Specific Considerations

Mobile operators often:

Use Carrier-Grade NAT (CGN) for IPv4 subscribers
Rapidly deploy IPv6 to mobile devices
Implement complex routing for roaming traffic
Use ASNs for both mobile data and fixed-line services

Use Case 7: Research and Education Networks

Universities, research institutions, and education networks use ASNs for academic connectivity.

Why Research Networks Need ASNs

Universities and research networks connect to GÉANT, Internet2 and their national research networks over BGP, so each campus or national network announces its own space from its own ASN.

Examples of Research Network ASNs:

GÉANT (European research network): AS20965
Internet2 (US research network): AS11537
CERN: AS513, European particle physics laboratory
JANET (UK education network): AS786

Use Case 8: Individuals and Small Multihomed Networks

A person can hold a public ASN. ripe-679 sets no size or company threshold, only multihoming, so a home lab or a one-person hosting setup qualifies once it takes BGP sessions from two providers (two VPS or transit providers, or one transit provider plus an Internet exchange). Typical uses are a personal /48 announced from two locations, anycast DNS, or a small hosting business that wants to keep its addresses when it changes provider.

Through our sponsorship an ASN costs €130 per year (as of September 2026), the €50 RIPE NCC fee included, for individuals and companies alike. The holder's name and postal address are published in the RIPE Database; phone numbers are not. The RIPE NCC assigns the number, you cannot choose it. What other sponsoring LIRs charge is compared in the ASN sponsorship price comparison.

With one upstream today, a private ASN or dn42 covers the learning phase (see the FAQ below).

Decision Framework: Do You Need an ASN?

You Probably NEED an ASN If:

In the RIPE region every item below also needs multihoming: two or more upstreams or peers, which the RIPE NCC request form asks you to name (ripe-679). ARIN issues a first ASN on request (NRPM section 5). RIPE proposal 2026-01 would drop the justification for a holder's first ASN, but it was still in drafting in September 2026.

You're an ISP providing Internet connectivity to customers
You require multi-homing with two or more upstream providers for business continuity
You operate a hosting service and need provider-independent addressing
You're implementing anycast for geographic load distribution
You need provider independence to maintain business flexibility
You participate in IXPs and establish peering relationships
Traffic engineering is critical for your business operations

You Probably DON'T Need an ASN If:

Single ISP connection meets your redundancy requirements
Provider-managed failover is sufficient for your needs
You lack BGP expertise and don't plan to develop it
Cost outweighs benefits for your use case
Small-scale operations don't justify the complexity
Testing or learning purposes (use private ASNs instead)

What an ASN Costs

Direct costs:

Registry fees: €130 per year for a sponsored ASN in the RIPE region through us, the €50 RIPE NCC fee included; $275 per year at ARIN in the 3X-Small category on the 2026 fee schedule ($288.75 from 2027); as a RIPE NCC member, €1,000 to join plus €1,800 per LIR account and €50 per ASN under the RIPE NCC Charging Scheme 2026 (ripe-848), then €1,894 with one ASN included from 2027 (ripe-867, adopted May 2026)
Transit from at least two upstreams, priced per provider and port
A BGP-capable router, or a software BGP daemon (BIRD, FRR, OpenBGPD) on a server
IP address space, if not already held

Indirect costs:

Staff training and expertise
Ongoing management overhead
Monitoring and maintenance
Compliance with RIR policies

For a detailed cost analysis, see ASN Registration Cost Breakdown (2026).

Getting Started with ASN Registration

If you've determined that your organization needs an ASN:

Assess your requirements: confirm you will be multihomed (two or more upstreams or peers)
Choose your RIR approach: direct membership or a sponsoring LIR
Gather documentation: prepare technical justification and organizational documents
Secure upstream agreements: establish relationships with ISPs before applying
Submit application: follow RIR-specific application procedures
Implement BGP: configure the sessions after assignment and publish a ROA for each prefix before the first announcement; 68.6% of IPv4 prefix-origin pairs were RPKI-valid on 1 August 2026 (NIST RPKI Monitor), see What Is RPKI? Route Origin Validation Explained. The RIPE NCC RPKI Dashboard also creates ASPA objects naming your upstreams since December 2025 (ASPA explained).

We sponsor ASNs in the RIPE region: €130 per year (€80 service fee plus the €50 RIPE NCC fee at cost), for companies and individuals. We prepare the file, file it with the RIPE NCC and maintain the records as your sponsoring LIR; your dashboard handles route objects, RPKI ROAs and LOAs. The wizard asks for a government ID (individuals) or a recent business registration document (organizations), the contracts or invoices of your two providers, and the prefix you will announce, or you order a /48 with the ASN. New orders can prepay year 2 for €234 in total (20% off year 2). Your ASN is typically live in 1 to 2 business days once your file is complete, RIPE NCC processing included. See the ASN registration service.

Frequently Asked Questions

Can a small company or an individual get an ASN?

Yes. ripe-679 sets no size threshold, only multihoming. Companies and individuals qualify once they take BGP sessions from two networks. A sponsored ASN costs €130 per year through us, RIPE NCC fee included. For an individual holder, name and address are published in the RIPE Database; phone numbers are not.

Do I need an ASN for a private network?

No. A network that does not exchange routes with the public Internet, or only runs BGP internally, uses a private ASN: 64512 to 65534 or 4200000000 to 4294967294 (RFC 6996). Private ASNs are free and need no registration; ranges and limits are in Private ASN ranges vs your own public ASN.

Can I get an ASN just for learning BGP?

In the RIPE region a public ASN needs a multihomed network (ripe-679), so a lab behind one upstream does not qualify. For practice you need no public number at all: use a private ASN (64512 to 65534, RFC 6996) or join dn42, a hobbyist BGP network with 1,500+ AS on its wiki in September 2026. Once you take BGP sessions from two providers, you meet the RIPE test.

How do major companies like Google use their ASNs?

Large companies like Google (AS15169) use their ASNs to:

Announce massive IP address blocks
Implement global anycast networks
Establish direct peering with thousands of networks
Control traffic engineering across worldwide infrastructure
Optimize content delivery and service performance

What happens if I get an ASN but don't use it?

In the RIPE region the RIPE NCC contacts holders of ASNs that are not announced. The number stays if it goes into use within three months; no reply within one month starts a three-month deregistration (AS Number clean-up). The annual fee is due while the number is registered. If you no longer need it, return it through your sponsoring LIR.

Summary and Next Steps

Every network in this article holds an ASN for the same reason: it announces its own prefixes to more than one neighbor and wants to choose how traffic enters and leaves. If you have two upstreams and your own address space, you qualify in the RIPE region; with one, a private ASN does the job until the second arrives. The step-by-step filing is in How to Register an ASN in 2026.

Understand requirements: ASN Registration Requirements by RIR (2026)
Prepare your file: How to Prepare Your ASN Justification