Autonomous System details for AS1921

Peering is a direct, often cost-neutral, interconnection between independent internet networks (Autonomous Systems). Instead of paying an intermediary (an upstream provider) to carry all their traffic, peered ASNs agree to exchange traffic destined for each other's networks and customers directly.

This results in lower latency, reduced costs, and more efficient paths for traffic. A peering relationship is distinct from a customer/provider relationship; peers generally only exchange routes to their own and their customers' networks, not the full internet routing table.

An upstream, also known as a transit provider, is an internet network (Autonomous System) that another AS pays to provide connectivity to the entire global internet.

Essentially, the customer Autonomous System announces its own IP address space (and that of its own customers, if any) to its upstream providers. In return, these upstreams provide the customer AS with routes to all other destinations on the internet, often including a default route (a path for any traffic not explicitly known).

This ensures that:

• Users and services within the customer AS can reach any website or service globally.
• The rest of the internet can reach the IP addresses advertised by the customer AS.

Unlike peering, which is typically a selective, often settlement-free exchange of traffic between networks and their customers, an upstream relationship is a commercial one where an AS purchases comprehensive internet access. Think of it like your home internet service provider (ISP); you pay them, and they connect you to everything online.

A downstream is an Autonomous System (customer) that pays another Autonomous System (the provider) for internet connectivity. The provider AS essentially acts as the upstream for its downstream customers.

In this relationship:

• The provider AS supplies its downstream customers with routes to the rest of the internet (or a portion of it, depending on the service agreement).
• The provider AS announces the IP address prefixes of its downstream customers to its own upstreams and peers, making the downstream customers reachable globally.

This is a classic customer-provider relationship. The downstream AS relies on its provider AS to carry its traffic to and from the wider internet. An individual end-user or a small business buying internet access from an ISP is effectively a downstream of that ISP's Autonomous System.

IP Ranges are blocks of IP addresses that an Autonomous System (AS) announces it controls. These ranges can be used by the organization operating the AS itself, or by its customers if the AS provides internet services.

The IPv6 address space is vastly larger than IPv4 by design, to accommodate the internet's ongoing growth. A single ASN might be allocated an enormous number of IPv6 addresses, even if they only use a fraction currently. This ensures plenty of addresses for future expansion.

ASN types categorize the primary function or nature of the organization operating the Autonomous System:

• isp: Primarily provides internet access to end-users or other businesses.
• hosting: Primarily provides services like web hosting, cloud computing, or data center colocation.
• education: Networks operated by universities or research institutions.
• government: Networks operated by government agencies.
• business: A large organization that manages its own network for internal use and external services, but isn't primarily an ISP.

The ASN type is provided by the ASN operator or inferred from activity on the ASN's networks, the ASN or organisation's name, or its website.

• Allocated: The date when the ASN was originally assigned to the organization by a Regional Internet Registry (RIR).
• Last updated: The date when the registration records for this ASN were last modified in the RIR's database. This could be due to changes in contact information, organization details, or other administrative updates.

These relationships are primarily inferred by analyzing BGP (Border Gateway Protocol) routing data collected from various points on the internet.

• Upstreams are identified as networks providing broad internet transit.
• Downstreams are customers receiving transit from the AS.
• Peers are networks exchanging traffic directly, often identified by the limited scope of routes they share.

Large networks, especially content providers or major ISPs, often rely heavily on peering to exchange traffic efficiently and cost-effectively. They might have enough peering partners to cover most of their traffic needs, reducing their reliance on paid upstream transit. Some may still use upstreams for redundancy or to reach niche parts of the internet not covered by peers.

If an ASN is an Internet Service Provider (ISP) or provides transit services, other ASNs (its customers) will connect to it as their downstream. The provider AS then carries traffic for these downstream customers to the rest of the internet.