Ronen Guri, director of business development, mobile backhaul, RAD, tells Keith Dyer that operators need to add sophisticated traffic management, performance monitoring and timing over packet technologies to their packet switched backhaul networks to enhance their end-to-end mobile SLAs.
Keith Dyer:
Ronen, what changes have you seen recently in the way your operator customers are addressing their backhaul requirements?
Ronen Guri:
Well if you were to go back a bit, clearly we would have seen mobile backhaul on a TDM/SDH infrastructure using T1/E1 interfaces. But then, as we all know, came 3G and the move to HSPA, which brought with it a change in the volumes and types of data traffic.
So then we started to see more and more mobile operators move to Ethernet to handle packet-switched backhaul.
Some started operating a hybrid model, switching voice over those legacy connections and data over the packet switched network. But we are actually now seeing more and more mobile operators moving today to take all their traffic, voice, data, and signaling over the packet-switched network. However, this move to packet-switched backhaul  has seen an emphasis on providing a fat pipe, not a smart pipe with enhanced class of service (CoS) and traffic management support. In some cases you will see some basic CoS support in the backhaul network but not end-to-end control.
We have observed in all cases that allied to this, is the fact that mobile operators will require SLAs for their backhaul networks. SLAs were an inherent part of TDM technology, second nature to it.
For historical reasons, they aren’t in packet technology and need to be recreated. This is done by deploying equipment engineered to support performance standards, high availability and throughput thresholds and monitor backhaul network behavior at all times so that both the mobile operator and the mobile backhaul provider, whether it is a wholesale carrier or the transport division of a fixed-mobile operator, can assure the end-to-end SLAs that they are commited to, before they impact subscriber services.
The big question facing everyone is how the backhaul transport provider can guarantee an end-to-end SLA for the mobile operator’s network.
Keith Dyer:
So if the move is from fat but dumb connectivity to smart backhaul, how does the industry equip itself to do that?
Ronen Guri:
Our main proposal, which works both in the case of a wholesale transport provider and for operators with self-owned backhaul, is to equip transport networks with Mobile Demarcation Device (MDDs). These are located at each and every point of interface between the mobile operator and the transport operator – depending on the network topology they can be at a cell site, a hub site or an aggregation node. These MDDs are devices that can do all that is needed to guarantee the SLA of the network: hierarchical traffic management, sophisticated performance monitoring, threshold testing and turn up, timing over packet and service validation tools.
Keith Dyer:
Hold on a moment. Most regional mobile operators have thousands, if not tens of thousands of cell sites. Can transport providers afford the CapEx for MDDs?Â
Ronen Guri:
I’d say they can’t afford not to. The alternatives don’t have the technology to support iron-clad SLAs. Of course, the MDD has to have all the technologies required at a price point that enables transport providers to deploy in the tens of thousands of cells that you mentioned. That’s not trivial
Keith Dyer:
When you talk of monitoring SLAs in the backhaul network, what is required to do that?
Ronen Guri:
You need to build parameters to provide SLAs for three or four or eight different classes of service, so each and every CoS has guaranteed availability, packet loss, delay and delay varation. In order to do that you need to provide traffic management and scheduling for all CoS across each and every EVC in the network.
If you can guarantee the SLAs in this manner then you can allow sophisticated traffic handling in the network, and that allows wholesale providers with several mobile operator customers to provide different SLAs according to what they all require. Another aspect that is required is the ability to be able to provide end-to-end monitoring and fault detection of the network itself. That requires an end-to-end view so that if any device has a problem, you can use an alternative path in the network. The requirements here are for fast detection times to boost the resiliency of the network itself as we are talking about measuring delay, delay variation, packet loss and the availability of the network, amongst other parameters, across every CoS within every connection.
Keith Dyer:
When you talk of assuring services across all packet-switched architectures, that always raises the question of timing and synchronisation. Does the MDD provide a solution to that issue as well?
Ronen Guri:
Yes, since packet-switched networks do not include inherent synchronisation mechanisms, they require complementary clock transfer solutions and nowhere is this issue of greater importance than in mobile backhaul. To ensure service quality for mobile traffic and avoid dropped calls, mobile networks require exceptionally stringent phase and frequency accuracy, which calls for equally exceptional high performance clocking capabilities. We have announced that our MDDs build on RAD’s position as a leader in timing over packet. RAD’s MDDs are equipped with the SyncToP suite of synchronisation and Timing over Packet technologies, which includes Synchronous Ethernet, IEEE 1588v2 (1588-2008) Precision Timing Protocol and NTR that are designed to provide clocking accuracy at SDH/SONET levels over packet transport. One reason why this versatility is crucial in an MDD is that for various reasons the mobile operator and the transport provider may be using different synchronization technologies in their respective networks.
Therefore the MDD must be equipped for every contingency. Another possibility is that the transport provider might want to sell timing capabilities and for that he needs timing support and interfaces in the MDD. On the other hand, if the timing is provided by the mobile operator, the transport provider needs to have 1588-TC support in-order to provide a better timing transport network.
Keith Dyer:
So you have enhanced SLA assurance, timing over packet functionality and traffic management features across the backhaul network, and that translates into the ability for operators to be able to manage their networks more efficiently and profitably.
Ronen Guri:
Absolutely. The important thing to realise is that when it has come to validation of services, it is the backhaul that has been the tricky part. The role of the MDD is to make available in the backhaul all the capabilities operators are used to having within the RAN and the core.
Keith Dyer:
And finally, what changes to the backhaul do you think we will see with the introduction of LTE?
Ronen Guri:
It’s still too early to tell , but with LTE deployment it’s important to note that the topology can change completely to a mesh architecture. More cell sites will be deployed and they will be talking to one another as well as to the network core. Data traffic patterns will change in the backhaul and transport networks will have to be optimized to respond to these shifting patterns.
This is definitely not a problem that can be solved by capacity alone — with our focus on smart pipes and on end-to-end SLA assurance, it’s clear that LTE and MDDs make enormous sense together.