ALPN (Application-Layer Protocol Negotiation)

E209795

ALPN (Application-Layer Protocol Negotiation) is a TLS extension that allows clients and servers to agree on which application-layer protocol (such as HTTP/2 or SPDY) to use over a secure connection during the TLS handshake.

All labels observed (3)

How this entity was disambiguated

Statements (46)

Predicate Object
instanceOf TLS extension
application-layer protocol negotiation mechanism
abbreviation ALPN
allowsNegotiationOf HTTP/1.1
HTTP/2
SPDY
custom application protocols
gRPC
associatedWith HTTP/2 over TLS
HTTPS
TLS 1.2
RFC 8446
surface form: TLS 1.3
avoids additional round trips for protocol negotiation
backwardCompatibility can fall back to HTTP/1.1 if HTTP/2 not negotiated
benefit enables protocol agility
reduces latency for protocol selection
supports coexistence of multiple application protocols on same port
definedIn TLS
surface form: Transport Layer Security (TLS)
failureBehavior connection may be terminated if no protocol is acceptable
fullName ALPN (Application-Layer Protocol Negotiation) self-linksurface differs
surface form: Application-Layer Protocol Negotiation
impact enables deployment of new application protocols without new ports
negotiatesOver encrypted TLS handshake messages
negotiationDirection client to server
negotiationModel client proposes list of protocols
negotiationPhase during TLS handshake
operatesAtLayer application layer
protocolIdentifierFormat opaque byte strings representing protocols
purpose negotiate application-layer protocol over a secure connection
relevance critical for modern web performance
replaces Next Protocol Negotiation
roleInHTTP2 selects HTTP/2 vs HTTP/1.1 over TLS
securityProperty protected by TLS handshake integrity
serverBehavior selects one protocol from client list
standardizedBy Internet Engineering Task Force
surface form: IETF
statusComparedToNPN standardized successor
supports multiple protocol identifiers in a single handshake
typicalPort 443
usedBy CDN providers
HTTP/2 implementations
QUIC-over-TLS implementations
reverse proxies
web browsers
web servers
usedFor multiplexing different application protocols on same TLS endpoint
usedIn TLS
surface form: TLS handshake
visibility not visible to application data layer after handshake

How these facts were elicited

Referenced by (5)

Full triples — surface form annotated when it differs from this entity's canonical label.

SPDY negotiationMechanism ALPN (Application-Layer Protocol Negotiation)
RFC 3546 title ALPN (Application-Layer Protocol Negotiation)
this entity surface form: Transport Layer Security (TLS) Extensions
NPN (Next Protocol Negotiation) replacedBy ALPN (Application-Layer Protocol Negotiation)
NPN (Next Protocol Negotiation) relatedTo ALPN (Application-Layer Protocol Negotiation)
ALPN (Application-Layer Protocol Negotiation) fullName ALPN (Application-Layer Protocol Negotiation) self-linksurface differs
subject surface form: ALPN
this entity surface form: Application-Layer Protocol Negotiation