Family gtp netlink specification

Summary

GPRS Tunnelling Protocol, user plane (GTP-U).

The gtp netdevice encapsulates and decapsulates user plane packets in GTP-U tunnels (GTPv0 and GTPv1-U, see 3GPP TS 29.060 and TS 29.281). This family manages the PDP contexts that describe the tunnels and triggers GTP-U echo requests. It is driven by user space control planes such as those built on libgtpnl.

The kernel registers the family with version 0, which the genetlink-legacy schema cannot express.

The notifications multicast on the “gtp” group are not described: PDP context additions and deletions, and GTP-U echo responses, reuse the NEWPDP, DELPDP and ECHOREQ command values of the requests.

Operations

newpdp

Create or update a PDP context.

attribute-set:

gtp

value:

0

dont-validate:

[‘strict’, ‘dump’]

flags:

[admin-perm]

do:

request

attributes:

[link, version, tid, peer-address, peer-addr6, ms-address, ms-addr6, flow, i-tei, o-tei, family, net-ns-fd]

delpdp

Delete a PDP context.

attribute-set:

gtp

dont-validate:

[‘strict’, ‘dump’]

flags:

[admin-perm]

do:

request

attributes:

[link, version, tid, ms-address, ms-addr6, i-tei, family, net-ns-fd]

getpdp

Get or dump one or more PDP contexts.

attribute-set:

gtp

dont-validate:

[‘strict’, ‘dump’]

flags:

[admin-perm]

do:

request

attributes:

[link, version, tid, ms-address, ms-addr6, i-tei, family, net-ns-fd]

reply

attributes:

[link, version, tid, peer-address, peer-addr6, ms-address, ms-addr6, flow, i-tei, o-tei, family]

dump:

reply

attributes:

[link, version, tid, peer-address, peer-addr6, ms-address, ms-addr6, flow, i-tei, o-tei, family]

echoreq

Send a GTP-U echo request to a peer. ms-address is not a mobile subscriber address here, but the local IPv4 address used as source of the request.

attribute-set:

gtp

dont-validate:

[‘strict’, ‘dump’]

flags:

[admin-perm]

do:

request

attributes:

[link, version, peer-address, ms-address, net-ns-fd]

Multicast groups

• gtp

Definitions

version

type:

enum

name-prefix:

gtp-

enum-name:

gtp-version

header:

linux/gtp.h

entries:

• v0

• v1

Attribute sets

gtp

link (u32)

doc:

ifindex of the gtp netdevice the context is attached to.

version (u32)

enum:

version

doc:

GTP version of the context, GTPv0 or GTPv1-U.

tid (u64)

doc:

Tunnel identifier, GTPv0 only.

peer-address (u32)

byte-order:

big-endian

display-hint:

ipv4

doc:

IPv4 address of the remote GSN peer (GGSN or SGSN). Also known as GTPA_SGSN_ADDRESS, kept for legacy user space.

ms-address (u32)

byte-order:

big-endian

display-hint:

ipv4

doc:

IPv4 address of the mobile subscriber served by the context.

flow (u16)

doc:

Flow label, GTPv0 only.

net-ns-fd (u32)

doc:

File descriptor of the network namespace of the gtp netdevice.

i-tei (u32)

doc:

Ingress Tunnel Endpoint Identifier, GTPv1-U only.

o-tei (u32)

doc:

Egress Tunnel Endpoint Identifier, GTPv1-U only.

pad (pad)

peer-addr6 (binary)

byte-order:

big-endian

display-hint:

ipv6

doc:

IPv6 address of the remote GSN peer (GGSN or SGSN).

ms-addr6 (binary)

byte-order:

big-endian

display-hint:

ipv6

doc:

IPv6 prefix of the mobile subscriber served by the context: a /64 prefix, with the lower 64 bits set to zero.

family (u8)

doc:

Address family (AF_INET or AF_INET6) of ms-address or ms-addr6, AF_INET when absent. The peer address uses the family of the tunnel socket.