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SKNK Field Notes · Routing and addressing terms
Internet Routing Glossary
Look up ASN, BGP, IPv6, PA, PI, RPKI, ROA, IRR, and peering. Each entry gives a plain-language definition, why it matters, and where to read more.
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Showing 28 of 28 terms
ASN and identity
Autonomous System Number(ASN)
The routing ID of a network: a number that identifies an autonomous system in inter-domain routing.
Why it matters
Announcements, filters, and peering all key on it. To speak for your own network, you need a number.
Related terms
ASN and identity
Autonomous System
A group of networks operated by one organisation under one external routing policy.
Why it matters
"Autonomous" means one external policy, not total isolation. Deciding whether you need an ASN is deciding whether you are one autonomous system.
Related terms
ASN and identity
External routing policy
The rules you follow when exchanging reachability with other autonomous systems: what you announce, accept, and refuse.
Why it matters
This is the real reason to get your own ASN. If the policy must be yours, the identity must be yours.
Related terms
ASN and identity
Sponsoring LIR
A relationship in which an LIR helps an End User request and maintain Internet number resources, under the applicable policy and agreement.
Why it matters
You get ASN and IPv6 resources without running a full RIPE NCC membership. In exchange, the sponsor administers the relationship — so you need to know where its boundary sits.
Related terms
BGP and routing
Border Gateway Protocol(BGP)
The inter-domain protocol networks use to advertise reachability: you say what you can reach, and your neighbours decide whether to believe you.
Why it matters
There is no central routing table on the Internet — BGP is the distributed one. Every path, and every filter, flows through it.
Related terms
BGP and routing
IP prefix
An address range written as address/length, for example 2001:db8::/32.
Why it matters
Routing, registries, and authorisations all speak in prefixes. Writing one precisely — length included — is step one of reading any result.
Related terms
BGP and routing
Origin ASN
The ASN a routing record marks as the source of a prefix's announcement.
Why it matters
Both RPKI and IRR check origins. Before acting on any result, ask: which number claims this prefix — and is it the one you expect?
Related terms
BGP and routing
Multihoming
Connecting a network to two or more external networks or upstreams.
Why it matters
Resilience is the upside; the cost is a routing policy of your own. That moment is when many people start needing an ASN.
Related terms
BGP and routing
IP transit
A paid upstream service that carries your traffic to the rest of the Internet.
Why it matters
Transit is a service you buy; peering is a relationship you exchange. Knowing which is which explains both your bill and your route table.
Related terms
BGP and routing
Peering
A direct interconnection where two networks exchange traffic under an agreed policy.
Why it matters
Free — but neither automatic nor universal: both sides must agree and must be able to meet. Looking it up in PeeringDB is only step one.
Related terms
BGP and routing
Internet Exchange Point(IXP)
A facility where many networks can meet and interconnect.
Why it matters
An IXP sells the meeting room, not the friendships. Ports in the fabric do not equal peers.
Related terms
BGP and routing
Route announcement
A BGP update that tells other networks: "you can reach this prefix through me."
Why it matters
A registry object is a record; an announcement is a live action. Read both together to see whether the route should exist and whether it is actually running.
Related terms
IPv6
IPv6
Version 6 of the Internet Protocol, with 128-bit addresses. The hard part of IPv6 is not the protocol — it is prefix lengths and subnet boundaries.
Why it matters
IPv4 intuition misleads in IPv6. Understanding the /48 and /64 hierarchy beats memorising the protocol.
Related terms
IPv6
IPv6 prefix
An IPv6 address range with a prefix length, e.g. 2001:db8::/32 or 2001:db8::/48.
Why it matters
The length decides how many subnets fit inside, and how the range appears in routing data.
Related terms
IPv6
IPv6 /48
An IPv6 prefix with a 48-bit length, commonly used to plan subnets for one site or customer.
Why it matters
"I need a /48" is common phrasing, but what you can do with it depends on the resource model and the service agreement. Ask first, plan after.
Related terms
IPv6
IPv6 /64
A 64-bit IPv6 prefix, the standard subnet boundary in IPv6 address plans.
Why it matters
Count the /64s inside a larger prefix and you instantly see how much room your plan has.
Related terms
IPv6
Provider Aggregatable(PA)
Address space tied to a provider's allocation and the resource relationship around it.
Why it matters
Before choosing PA, ask: if you change providers, does this prefix have to be renumbered? If yes, plan for it first.
Related terms
IPv6
Provider Independent(PI)
Address space intended not to depend on any single provider — still bound by registry rules.
Why it matters
PI survives provider changes without renumbering; the price is your own registry relationship, annual fees, and ROA/IRR upkeep.
Related terms
IPv6
IPv6 subnetting
Dividing a larger IPv6 prefix into smaller prefixes according to a plan.
Why it matters
Turning a resource prefix into site, service, and infrastructure boundaries is the most time-consuming — and most worthwhile — part of IPv6 planning.
Related terms
Routing security
Resource Public Key Infrastructure(RPKI)
A cryptographic system that publishes and validates who is authorised to announce what.
Why it matters
RPKI does not prevent routing mistakes; it makes them visible. That visibility is most of the defence.
Related terms
Routing security
Route Origin Authorisation(ROA)
A signed authorisation: "ASN X may announce prefix Y, up to length Z."
Why it matters
A ROA is the input RPKI validation reads. Without one, a validator can only answer Unknown.
Related terms
Routing security
Maximum length
The longest prefix length a ROA authorises.
Why it matters
Announce something more specific than max-length and validation flips to Invalid. More specific is not always better in RPKI.
Related terms
Routing security
Internet Routing Registry(IRR)
A registry system for publishing routing-policy objects, used by operators and filtering systems.
Why it matters
IRR and RPKI answer related but different questions. Before relying on a routing filter, know which one it actually uses.
Related terms
Routing security
Route object
An IRR object describing an IPv4 route and its origin ASN.
Why it matters
Operators build filters from these. But an object is not a live route — the most common confusion on this page.
Related terms
Routing security
ROUTE6 object
The IRR object for an IPv6 inter-domain route and its originating ASN.
Why it matters
It is the IPv6 counterpart of a route object. Read it separately from live BGP observations.
Related terms
Routing security
RPKI Valid
Validation result: this announcement matches an applicable ROA.
Why it matters
Valid answers exactly one question: authorisation. Your service can be down and RPKI still says Valid.
Related terms
Routing security
RPKI Invalid
Validation result: the announcement conflicts with ROA data — for example, the origin is not the authorised one.
Why it matters
Before changing policy on an Invalid, check which of prefix, origin, or length disagrees. Then act.
Related terms
Routing security
RPKI Unknown / Not Found
Validation result: no applicable authorisation found in the validator's data.
Why it matters
Unknown is not Invalid. It is common for small networks with no ROA at all — not a sign of wrongdoing. Read it with its source and timestamp.
Related terms
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