- 01Virtualised Evolved Packet CorevEPC
- 02Home Subscriber ServerHSS
- 03Packet Data Network GatewayPDN-GW
- 04Diameter Routing AgentDRA
- 05Equipment Identity RegisterEIR
- 06Policy and Charging Rules FunctionPCRF
- 07Messaging CenterSMSC
- 08IP-SMS GatewayIP-SM-GW
- 09Gateway Mobile Location CentreGMLC
- 10IMS Core with TAS and MRFIMS
- 11Access Network Discovery and Selection FunctionANDSF
- 12Cell Broadcast CentreCBC
An LTE core without a DRA needs every element to maintain a direct Diameter connection to every other. Six core elements and ten roaming partners means dozens of peer connections: each one a separate configuration to maintain, a separate failure point to monitor.
Diameter is the signalling protocol that connects every element in an LTE core. The MME authenticates subscribers against the HSS. The PGW receives policy rules from the PCRF. The OCS tracks charging events. Every one of these exchanges requires a configured peer connection.
In a network without a DRA, every element connects directly to every other element it needs to reach. Add a new HSS node and every element that queries the HSS needs reconfiguring. Add a new roaming partner and every internal element that needs to accept their signalling needs a new peer connection. The mesh grows with every change. At scale, modifying the network topology becomes an exercise in touching dozens of configurations simultaneously.
A mesh that grows with every change
A Diameter network without a routing agent is a mesh: every element talks directly to every other element it needs to reach. Add a node, update a peer, onboard a roaming partner — and the configuration change propagates across the entire mesh.
Connect once, route everywhere
The Ouroboros DRA replaces that mesh with a hub. Every Diameter-speaking element in the network connects to the DRA once. The DRA routes each message to the correct destination — whether that is an internal element like the HSS or PCRF, or an external roaming partner's Diameter infrastructure. Elements do not need to know where other elements are located. They know the DRA's address.
Routing on the subscriber
Routing decisions happen in real time. The DRA is also the Subscription Locator Function (SLF) of the network: it reads the subscriber identity of each request — the IMSI from the Subscription-Id or User-Name AVP, the MSISDN, the IMS public identity (SIP or tel URI) or the private identity (IMPI) — and relays the request to the HSS, OCS or PCRF that holds that subscriber. The clients never query an SLF themselves: no Dx or Dh exchange, a single Diameter peer. The same table locates the ported-in and ported-out numbers, so number portability comes with it. Routing also works on origin host and realm, by priority, with destination realm substitution. Load balancing across nodes, fall-back routes and failover are handled here, and record route keeps the path of every message.
Screened at the boundary
Inbound Diameter traffic from roaming partners is screened at the DRA boundary, which acts as a Diameter Edge Agent. Black and white lists on message header and AVP contents, IMSI filtering by origin realm or host, and dropping rules apply before any traffic reaches internal elements. AVP rewriting rules (prefix, suffix, deletion) adapt partners' messages, topology hiding keeps the home network anonymous, and throttling protects the core from roaming accidents and denial-of-service attacks.
DRA — Diameter hub across the 4G core
Internal signalling, roaming control, number portability, screening — one hub.
Centralising internal Diameter signalling
An operator with MME, HSS, PCRF, OCS, SGW, and PGW points each at the DRA. A change to any element's address or capacity updates the DRA routing table. The other elements stay untouched.
Roaming Diameter control
Roaming partner connections terminate at the DRA. A new roaming agreement means one peer connection at the DRA boundary, not a configuration change across every internal element.
Signalling security and screening
Inbound Diameter messages from roaming partners are screened at the DRA boundary before reaching internal elements. Messages outside expected parameters are blocked without operator intervention, and throttling caps the traffic of a misbehaving partner.
Several HSS, OCS or PCRF
An operator running several HSS, OCS or PCRF instances, or hosting MVNOs, lets the DRA act as the Subscription Locator Function: it picks the right one from the IMSI, the MSISDN or the IMS identity of each request. The other elements keep a single Diameter peer.
Number portability on Diameter
Ported-in and ported-out numbers are entered in the subscriber location table with the HSS or the operator that serves them. Requests addressed by MSISDN — Sh from the application servers, S6c for SMS over Diameter, SLh from the GMLC — reach the right destination without a portability query in each element.
Ouroboros is more agile and flexible than bigger ones. Its prices are competitive. The genuine expertise of the team enables a true dialogue with our partners.
Frédéric Maro
VP Network & Advanced Projects · Sierra Wireless
Hub-and-spoke Diameter topology
Every network element connects to the DRA once, replacing the N×N peer mesh. Adding a network element or roaming partner requires one configuration change, not N.
Real-time routing decisions
Routing tables update dynamically without interrupting in-flight Diameter sessions. Network topology changes such as new nodes or failed peers take effect without session loss.
Roaming partner boundary control
Inbound roaming Diameter traffic terminates at the DRA and is inspected before reaching internal elements. Roaming partner signalling is controlled at the perimeter, not managed per internal element.
Active-active geographic redundancy
DRA state replicates across sites. A site failure does not disrupt Diameter routing. Signalling continuity is maintained even during a primary site outage.
Subscription Locator Function (SLF)
The HSS, OCS or PCRF of each subscriber is found from the IMSI (Subscription-Id, User-Name), the MSISDN, the IMS public identity or the IMPI, per Diameter application. Multi-HSS, multi-OCS, MVNO hosting and number portability work without changes on the clients, and without Dx or Dh queries.
AVP rewriting and filtering rules
Black and white lists on header and AVP contents, dropping rules, and AVP rewriting by prefix, suffix or deletion. Interworking issues with partners are fixed at the DRA, not in every element.
Topology hiding and throttling
The home network topology stays anonymous to roaming partners, and throttling prevents network failures caused by roaming accidents or denial-of-service attacks.
SCTP multihoming
Peers connect over SCTP with several IP addresses or over TCP. A link failure does not drop the Diameter association.
IPv4, IPv6 and dual-stack
Every interface runs over IPv4, IPv6 or both. The element fits an IPv6 core or a mixed network without a separate configuration.
The DRA is not a glamorous product. It is the element that makes the rest of the network manageable as it grows. Without it, every topology change propagates through the configuration of every element that connects to the changed component: a new node, a capacity upgrade, a new roaming agreement. With it, the change happens once.
The Ouroboros DRA is available standalone, on OPEX rental, and integrates with Diameter elements from any vendor. For operators adding LTE to a 3G core, or managing a growing roster of roaming partners, signalling control does not require a multi-vendor signalling portfolio.
How many Diameter-capable elements and roaming partners are you managing today? We'll show what the hub-and-spoke topology removes from your operations workload.
Product datasheet4G / LTE · 4G/LTE
Diameter Routing Agent (DRA)
An LTE core without a DRA needs every element to maintain a direct Diameter connection to every other. Six core elements and ten roaming partners means dozens of peer connections: each one a separate configuration to maintain, a separate failure point to monitor.
In production since 2015 · 99.999% availability
The peer mesh that grows with every change
Diameter is the signalling protocol that connects every element in an LTE core. The MME authenticates subscribers against the HSS. The PGW receives policy rules from the PCRF. The OCS tracks charging events. Every one of these exchanges requires a configured peer connection.
In a network without a DRA, every element connects directly to every other element it needs to reach. Add a new HSS node and every element that queries the HSS needs reconfiguring. Add a new roaming partner and every internal element that needs to accept their signalling needs a new peer connection. The mesh grows with every change. At scale, modifying the network topology becomes an exercise in touching dozens of configurations simultaneously.
The mesh becomes a hub.
A mesh that grows with every change
A Diameter network without a routing agent is a mesh: every element talks directly to every other element it needs to reach. Add a node, update a peer, onboard a roaming partner — and the configuration change propagates across the entire mesh.
Connect once, route everywhere
The Ouroboros DRA replaces that mesh with a hub. Every Diameter-speaking element in the network connects to the DRA once. The DRA routes each message to the correct destination — whether that is an internal element like the HSS or PCRF, or an external roaming partner's Diameter infrastructure. Elements do not need to know where other elements are located. They know the DRA's address.
Routing on the subscriber
Routing decisions happen in real time. The DRA is also the Subscription Locator Function (SLF) of the network: it reads the subscriber identity of each request — the IMSI from the Subscription-Id or User-Name AVP, the MSISDN, the IMS public identity (SIP or tel URI) or the private identity (IMPI) — and relays the request to the HSS, OCS or PCRF that holds that subscriber. The clients never query an SLF themselves: no Dx or Dh exchange, a single Diameter peer. The same table locates the ported-in and ported-out numbers, so number portability comes with it. Routing also works on origin host and realm, by priority, with destination realm substitution. Load balancing across nodes, fall-back routes and failover are handled here, and record route keeps the path of every message.
Screened at the boundary
Inbound Diameter traffic from roaming partners is screened at the DRA boundary, which acts as a Diameter Edge Agent. Black and white lists on message header and AVP contents, IMSI filtering by origin realm or host, and dropping rules apply before any traffic reaches internal elements. AVP rewriting rules (prefix, suffix, deletion) adapt partners' messages, topology hiding keeps the home network anonymous, and throttling protects the core from roaming accidents and denial-of-service attacks.
DRA — Diameter hub across the 4G core
How operators use it.
Internal signalling, roaming control, number portability, screening — one hub.
Centralising internal Diameter signalling
An operator with MME, HSS, PCRF, OCS, SGW, and PGW points each at the DRA. A change to any element's address or capacity updates the DRA routing table. The other elements stay untouched.
Roaming Diameter control
Roaming partner connections terminate at the DRA. A new roaming agreement means one peer connection at the DRA boundary, not a configuration change across every internal element.
Signalling security and screening
Inbound Diameter messages from roaming partners are screened at the DRA boundary before reaching internal elements. Messages outside expected parameters are blocked without operator intervention, and throttling caps the traffic of a misbehaving partner.
Several HSS, OCS or PCRF
An operator running several HSS, OCS or PCRF instances, or hosting MVNOs, lets the DRA act as the Subscription Locator Function: it picks the right one from the IMSI, the MSISDN or the IMS identity of each request. The other elements keep a single Diameter peer.
Number portability on Diameter
Ported-in and ported-out numbers are entered in the subscriber location table with the HSS or the operator that serves them. Requests addressed by MSISDN — Sh from the application servers, S6c for SMS over Diameter, SLh from the GMLC — reach the right destination without a portability query in each element.
“Ouroboros is more agile and flexible than bigger ones. Its prices are competitive. The genuine expertise of the team enables a true dialogue with our partners.”
Frédéric Maro
VP Network & Advanced Projects · Sierra Wireless
Specifications.
Inside the platform.
Hub-and-spoke Diameter topology
Every network element connects to the DRA once, replacing the N×N peer mesh. Adding a network element or roaming partner requires one configuration change, not N.
Real-time routing decisions
Routing tables update dynamically without interrupting in-flight Diameter sessions. Network topology changes such as new nodes or failed peers take effect without session loss.
Roaming partner boundary control
Inbound roaming Diameter traffic terminates at the DRA and is inspected before reaching internal elements. Roaming partner signalling is controlled at the perimeter, not managed per internal element.
Active-active geographic redundancy
DRA state replicates across sites. A site failure does not disrupt Diameter routing. Signalling continuity is maintained even during a primary site outage.
Subscription Locator Function (SLF)
The HSS, OCS or PCRF of each subscriber is found from the IMSI (Subscription-Id, User-Name), the MSISDN, the IMS public identity or the IMPI, per Diameter application. Multi-HSS, multi-OCS, MVNO hosting and number portability work without changes on the clients, and without Dx or Dh queries.
AVP rewriting and filtering rules
Black and white lists on header and AVP contents, dropping rules, and AVP rewriting by prefix, suffix or deletion. Interworking issues with partners are fixed at the DRA, not in every element.
Topology hiding and throttling
The home network topology stays anonymous to roaming partners, and throttling prevents network failures caused by roaming accidents or denial-of-service attacks.
SCTP multihoming
Peers connect over SCTP with several IP addresses or over TCP. A link failure does not drop the Diameter association.
IPv4, IPv6 and dual-stack
Every interface runs over IPv4, IPv6 or both. The element fits an IPv6 core or a mixed network without a separate configuration.
The DRA is not a glamorous product. It is the element that makes the rest of the network manageable as it grows. Without it, every topology change propagates through the configuration of every element that connects to the changed component: a new node, a capacity upgrade, a new roaming agreement. With it, the change happens once.
The Ouroboros DRA is available standalone, on OPEX rental, and integrates with Diameter elements from any vendor. For operators adding LTE to a 3G core, or managing a growing roster of roaming partners, signalling control does not require a multi-vendor signalling portfolio.
HSS
S6a authentication traffic between MME and HSS routes through the DRA. The HSS is one of the DRA's primary internal routing targets.
PCRF
Gx interface traffic between the PGW and PCRF routes through the DRA. Load balancing across PCRF instances is managed at the DRA.
vEPC
The MME, SGW, and PGW all generate Diameter signalling. All three connect to the DRA as their single signalling routing point.
Next step
How many Diameter peer connections does your network currently maintain?
How many Diameter-capable elements and roaming partners are you managing today? We'll show what the hub-and-spoke topology removes from your operations workload.