How an IPX Carrier
can Optimize LTE Roaming
Roaming in LTE
Connectivity between mobile network operators (MNO) in
4G LTE is much more complex than it was in legacy networks.
This complexity is primarily due to the change in focus. LTE is
not a voice-focused roaming environment, but rather a data-
centric environment. This significant change had prompted the
GSMA to define guidelines on how roaming for LTE should
be implemented. One of the requirements states that the
interconnection of LTE network requires the use of an IPX (IP
There may be MNOs considering interconnections to roaming
partners on a bilateral basis, however a direct approach would
require many point-to-point connections and could not be
considered very scalable and resource efficient.
However, what the GSMA left out in its requirements are the
functional specifications within an IPX carrier service provision.
To fulfill this gap, we will outline briefly what are the typical
services an IPX carrier should offer and what value-added
services could be provided to mobile network operators
The rapid increase of launched commercial LTE services
accelerates the need to provide LTE roaming. The first
commercial roaming LTE traffic began in 2012. Establishing
technical roaming for LTE relationships with hundreds of LTE
roaming partners is a very resource intensive activity for
Therefore, the alternative favors connecting to one or multiple IPX
carriers and receiving access to their infrastructure and services.
Once connected to an IPX carrier, the MNO can receive basic
1 According GSA at the start of 2013, 145 commercial LTE networks had been
launched in 66 counties.
How an IPX Carrier can Optimize LTE Roaming
IPX transport services to interconnect the various MNOs that the
IPX has connected to its network. As new MNOs get connected
to the IPX network, they can be easily interconnected to the other
MNOs with minimal effort from all sides.
IPX Value Add for LTE Roaming
In addition to basic transportation services, there are many
other challenges that MNOs need to solve. Here again, the IPX
carrier can serve as an outsourcing partner for challenges such
as Diameter normalization, global Diameter routing, scaling
and securing the signaling plane and its content, but only on
condition that the IPX carrier has deployed both a Diameter
Routing Agent (DRA) and a Diameter Edge Agent (DEA).
GENBAND QUANTiX DSC: Combining DRA, DEA,
IWF and more functionality on one platform
The first interfaces that need to be implemented to support
LTE roaming are the Diameter-based interfaces S6a and
S6d between the MME/SGSN on one side and the HSS on
the other side. Further on, other interfaces like S9 that lie
between the home PCRF and the visited PCRF are required
as well. Potentially more interfaces, like Gy for billing, might
be included over time especially once a local breakout will
be used and the home network needs to receive real-time
GENBAND’s QUANTiX DSC is 100% complaint with 3GPP
Diameter Routing Agent (DRA) requirements, 3GPP Diameter
Edge Agent (DEA), GSMA IR.88 requirements and much
more. When an IPX carrier deploys the QUANTiX DSC,
it solves all the relevant IPX Diameter routing and security
The QUANTiX DSC supports the advanced routing
functionalities for the S6a, S6d and S9 interfaces as per
It supports a Diameter Gateway functionality to allow
different implementation of the same Diameter protocol,
also called Diameter dialects, to be normalized and
correctly work with each other. This same Diameter
Gateway function also allows interworking between
Diameter and many other protocols like LDAP, Radius,
SS7-MAP, SS7-Camel, etc.
Via its Diameter Gateway, the DSC allows access to LDAP
databases that could hold routing rules and additional
information that can be helpful in routing.
It enables advanced routing functions that allow for
alternative routes and can offload routing processing from
MNO’s MMEs like mapping IMSIs to Realms.
It provides IPsec and TLS security and interworking to/
from links using no IPsec or TLS.
The QUANTiX DSC solution allows for the option to have
an internal SEG (Security Gateway) functionality for
terminating IPsec and TLS or to interwork with an external
third party’s SEG.
It offers gateway functionality for IPv6 and IPv6 next to
TCP and SCTP, where it can also be used as an SCTP
It uses full topology hiding, not only for most of the visible
network node addresses but also addresses inside any
AVP that contains sensitive information. This is supported
currently for S6a, S6d, S9 and Gy.
It offers advanced Access Control Lists (ACL) to manage
how much signaling is allowed between various nodes for
the various applications.
It supports mechanisms to prevent flooding, such as a
mechanism to prevent a Denial of Service attack.
It allows for advanced health and error rate monitoring
for assuring better QoS (such as using alternative route for
links with high delay or high number of error rates).
It enables accounting and billing functionalities to allow
for Transaction Data Record generation for signaling
It allows for Roaming statistics and KPI generation (and
integration with existing OSS/BSS solutions).
It offers testing and tracing functionality allowing an IPX
carrier better troubleshooting tools, allows to test and
trace the behavior of network nodes that are new or have
updated software, prior to sending live traffic.
The QUANTiX DSC supports the IWF function enabling
SS7-MAP and Diameter interworking according 3GPP TS
29.305, covering mobility management and IMEI check
It supports multi-tenancy to allow an IPX carrier to offer
virtual DEA and/or DEA functionalities to its customers.
It supports Intelligent Roaming functionalities, like steering
of roaming traffic and the QUANTiX DSC can also be
used for GLR (Gateway Location Register) purposes.
It supports routing and gateway functionalities that are
required for the 2014 EU Data Roaming regulation.
By deploying the GENBAND QUANTiX DSC, the IPX carrier
has a future-proofed network, shortened time-to-market via
the advanced IOT table with most of the leading DEA, MME
and HSS vendors and supports of all Diameter interfaces (and
many legacy interfaces as well).
The GENBAND QUANTiX DSC is a Diameter solution that
combines intelligent, context-aware signaling with a Diameter
router, load balancer, and gateway. This all-in-one platform
provides simplified control, superior scalability, and seamless
connectivity so that networks can support subscribers’ heavy
and growing use of mobile broadband data. The DSC
Diameter Gateway offers instant and cost-effective, any-to-
any connectivity between Diameter-based interfaces and
systems that use legacy signaling protocols. With seamless
connectivity between all Diameter network elements, legacy
network elements, and an unlimited variety of third-party
vendors, MVNOs, MVNEs, roaming partners, and service
providers have an easy migration path with countless
opportunities to pursue alternative business models and
introduce additional revenue sources.
How an IPX Carrier can Optimize LTE Roaming
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This document and any products or functionality it describes are subject to change without
notice. Please contact GENBAND for additional information and updates.