Package: simu5g.corenetwork.trafficFlowFilter

TrafficFlowFilter

simple module

Maps IP 4-Tuples to Traffic Flow Template (TFT) identifiers, which are used by the GtpUser module next to it. It interacts with the Binder to determine the destination of the packet. Resides, with the GtpUser, in the UserPlaneRelay of every node that ends GTP-U tunnels: eNodeB, gNodeB, PgwStandard and Upf (also as the UPF of a MecHost). For instance, in a Upf module acting as the entry point of the 5G network, it identifies the destination endpoint of the GTP tunnel that the packet should traverse, which is the gNodeB serving the destination User Equipment (UE). In a base station, it receives the UEs' uplink datagrams straight from the cellular NIC.

The module also assigns each packet entering the tunnel its QoS Flow Identifier (QFI). At a core-network tunnel entry (Upf, PgwStandard, a MEC host's UPF) the QFI-assignment rules are installed by the node's control-plane entry point, UserPlaneNodeControl, on behalf of the CoreControl, the SMF stand-in (the rules are authored in its dlQfiRules parameter): they model the packet detection and QoS enforcement rules (PDR/QER) that the SMF installs into a UPF over N4 signaling -- a real UPF holds no classification policy of its own, and neither does this module. A packet matching no rule gets QFI 0 (the default flow).

A base station is no rule-enforcement point: no SMF installs classification rules there, and none can be authored for it. An uplink packet that SDAP already attributed to a QoS flow keeps that QFI on its way into the core network; uplink traffic from a stack without SDAP is classified by a built-in DSCP-as-QFI residual.

Unstructured sessions (see the sessionType parameter of LteUe). At a base station, their uplink payload, which SDAP delivers up as the "unstructured" protocol, goes to the session's anchor on the QoS flow SDAP attributed it to: no MEC steering and no local delivery, which go by an IP destination the payload has none of. At the anchor UPF, a datagram of the data network addressed to an Unstructured session's N6 address is that session's downlink (see UserPlaneNodeControl): the N6 tunnel's UDP/IP headers go, and the payload goes into the session's tunnel on the default QoS flow, with no rule evaluated.

Packets that name their session. At a UPF or PGW, a packet tagged with its session (a SessionTag) is that session's downlink, and goes into the session's tunnel without being classified by its destination address. The downlink frames of the Ethernet sessions come from the node's EthernetSessionBridge: a frame goes on the QFI of the first rule that matches the full frame (a dscpAsQfi rule does not match a frame), else the default QoS flow. The replies of the node's Ipv6NdResponder on the links of the IPv6 sessions go on the default QoS flow.

Used in compound modules

Name	Type	Description
UserPlaneRelay	compound module	The user-plane relay of a node that ends GTP-U tunnels: the "relay" between the two protocol stacks in the user-plane stack diagrams of 3GPP (TS 23.401, 23.501, 38.300). At a base station it relays between the radio interface and the N3/S1-U tunnels, at a Upf or PgwStandard between the data network (N6/SGi) and the tunnels toward the base stations or other UPFs.

Parameters

Name	Type	Default value	Description
binderModule	string	"binder"
ownerType	string		Must be one of ENODEB, GNODEB, PGW, UPF, UPF_MEC
gateway	string	""	The core network gateway of a base station or a MEC host's UPF, a module path relative to the network; unused at an anchor (PGW, UPF), which is the gateway itself
mecHost	string	""	At a base station: the MEC host the base station steers traffic to (see the mecHost parameter of eNodeB); empty = none
fastForwarding	bool	true

Properties

Name	Value	Description
display	i=block/filter

Gates

Name	Direction	Size	Description
in	input		The user data entering the tunnels
out	output		The classified user data, to the GtpUser

Source code

//
// Maps IP 4-Tuples to Traffic Flow Template (TFT) identifiers, which are used by the ~GtpUser module
// next to it. It interacts with the ~Binder to determine the destination of the packet.
// Resides, with the ~GtpUser, in the ~UserPlaneRelay of every node that ends GTP-U tunnels: ~eNodeB,
// ~gNodeB, ~PgwStandard and ~Upf (also as the UPF of a ~MecHost).
// For instance, in a ~Upf module acting as the entry point of the 5G network, it
// identifies the destination endpoint of the GTP tunnel that the packet should traverse, which is the gNodeB
// serving the destination User Equipment (UE). In a base station, it receives the UEs'
// uplink datagrams straight from the cellular NIC.
//
// The module also assigns each packet entering the tunnel its QoS Flow Identifier
// (QFI). At a core-network tunnel entry (~Upf, ~PgwStandard, a MEC host's UPF) the
// QFI-assignment rules are installed by the node's control-plane entry point,
// ~UserPlaneNodeControl, on behalf of the ~CoreControl, the SMF stand-in (the rules are
// authored in its dlQfiRules parameter): they model the packet detection and QoS
// enforcement rules (PDR/QER) that the SMF installs into a UPF over N4 signaling --
// a real UPF holds no classification policy of its own, and neither does this
// module. A packet matching no rule gets QFI 0 (the default flow).
//
// A base station is no rule-enforcement point: no SMF installs classification rules
// there, and none can be authored for it. An uplink packet that SDAP already
// attributed to a QoS flow keeps that QFI on its way into the core network; uplink
// traffic from a stack without SDAP is classified by a built-in DSCP-as-QFI
// residual.
//
// Unstructured sessions (see the sessionType parameter of ~LteUe). At a base station,
// their uplink payload, which SDAP delivers up as the "unstructured" protocol, goes
// to the session's anchor on the QoS flow SDAP attributed it to: no MEC steering and
// no local delivery, which go by an IP destination the payload has none of. At the
// anchor UPF, a datagram of the data network addressed to an Unstructured session's
// N6 address is that session's downlink (see ~UserPlaneNodeControl): the N6 tunnel's
// UDP/IP headers go, and the payload goes into the session's tunnel on the default
// QoS flow, with no rule evaluated.
//
// Packets that name their session. At a UPF or PGW, a packet tagged with its session (a
// ~SessionTag) is that session's downlink, and goes into the session's tunnel without being
// classified by its destination address. The downlink frames of the Ethernet sessions come
// from the node's ~EthernetSessionBridge: a frame goes on the QFI of the first rule that
// matches the full frame (a dscpAsQfi rule does not match a frame), else the default QoS
// flow. The replies of the node's ~Ipv6NdResponder on the links of the IPv6 sessions go on
// the default QoS flow.
//
simple TrafficFlowFilter
{
    parameters:
        @display("i=block/filter");

        string binderModule = default("binder");
        string ownerType @enum(ENODEB,GNODEB,PGW,UPF,UPF_MEC); // Must be one of ENODEB, GNODEB, PGW, UPF, UPF_MEC
        string gateway = default("");  // The core network gateway of a base station or a MEC host's UPF, a module path relative to the network; unused at an anchor (PGW, UPF), which is the gateway itself
        string mecHost = default("");  // At a base station: the MEC host the base station steers traffic to (see the mecHost parameter of ~eNodeB); empty = none
        bool fastForwarding = default(true);
    gates:
        input in;  // The user data entering the tunnels
        output out;  // The classified user data, to the ~GtpUser
}

File: src/simu5g/corenetwork/trafficFlowFilter/TrafficFlowFilter.ned