Jul 13, 2010

The LTE Diaries: Come Along for the LTE Development Ride

by Dennis Cox

NOTE: This is one post in a long series, catch up on the most recent LTE development updates, or check out our recent LTE webcast.

Several BreakingPoint engineers are starting work on adding Long-Term Evolution (LTE) support for the BreakingPoint Storm CTM. I’m excited about this development, as well as the way in which we are going to share the news. Rather than have you wait for a press release with a long list of our new LTE-based features, we are going to use this blog to bring you along for the rapid development ride. Over the next few weeks you will hear directly from BreakingPoint engineers and myself about lessons learned in LTE network simulation and performance. These posts will provide you with a look inside our development team and grant you visibility into the evolution of our product, nearly in real-time. Let's get started.

Please note: Some writing on this blog post will make generalities and skip over details, we do this to simplify the concepts. Writing about something like LTE with the needed precision would bore the majority of our readership. If you want to get into the details, however, post a question or comment below.

LTE 101

Before I dive into the first two steps of development, let's review a few points about LTE:

There is often confusion, caused by marketing, about what LTE truly is and does. LTE does stand for "long-term evolution", but is typically marketed as "4G". In reality, LTE is really 3.99G, which does not fully comply with the IMT Advanced 4G requirements, but is a pre-4G standard that moves us towards actual 4G.
One of the key components of LTE is, of course, the mobile device, otherwise known as User Equipment or UE. A UE connects over radio frequency (RF) to a tower that transmits on the LTE spectrum.
One of the most significant parts of LTE, and really where the "evolution" comes in, is eNodeB. Think of eNodeB as comprising all the communications architecture that makes LTE possible, including communications between the tower, the SGW (Serving Gateway) and the MME (Mobility Management Entity), which is the main signaling node that deals with registration and a lot more.
To visualize: In LTE, you have the UE connected to eNodeB, then eNodeB connected to MME, then eNodeB connected to SGW.

Have I lost you? Let me break down our development schedule and make it clear why we are doing what we’re doing.

Step 1: SCTP Support

We start next week implementing the Stream Control Transmission Protocol (SCTP), which we will provide support for in the two modes we care about, either on top of UDP or on top of the IP stack. SCTP goes a long way toward providing a more reliable transport protocol to a potentially unreliable service such as IP. Within the protocol there are many functions that allow for detection of data corruption, loss of data and data duplication. Scott Canion will be writing a post soon on what is so great about SCTP.

SCTP is a transport layer that will run in the BreakingPoint network processors. Because of our unique architecture and use of network processors we will be able to rapidly develop SCTP and allow all of our application protocols to use this transport layer. For example, you can simulate H.323 to transmit over SCTP simply by clicking on a protocol field. Think of it this way; within the BreakingPoint product we are setting up a series of SCTP servers (Windows, Linux, etc.), and you'll be able to communicate all of your protocols using this transport layer. (UPDATE: Read our post on SCTP Support)

Step 2: DHCP Client Support

In parallel, we are adding DHCP Client support into our firmware. When DHCP is introduced, BreakingPoint users will go to the Network Neighborhood window to input the amount of clients they want to simulate and specify they want each of them to get an IP address. I could write a lot about why this is important and how it works, but I'll leave that for future blog posts. For now, the important point is that this is how some UEs (the mobile device) get assigned an IP address. Remember, LTE is a moving standard with different implementations, so your mileage may vary.

Step 3: GTP Support

GTP is a tunneling protocol important to LTE networks. While SCTP runs from the eNodeB up to the MME, GTP runs from the eNodeB through the SGW to the PGW (Packet Data Network Gateway). This effectively gives you a VPN connection to your phone provider's Internet service, and is important because it allows you to head on over to the Android store or check out a web page. As we said above, your phone may have an IP address through the DHCP Client, but it is all tunneled through the telecom network using GTP. (UPDATE: Read our post on GTP Support)

Step 4: S1AP Support

Additionally, to make this all happen, you need S1AP support. S1AP is a series of messaging protocols that work over ASN.1 encoding and is the control plane signaling protocol between the eNodeB and MME. This provides additional mobility functions for the UE, among other benefits. (UPDATE: Read our post on S1AP support)

Buckle Up, It’s Going To Be a Very Fast Ride

Our rapid development schedule includes the introduction of support for SCTP and DHCP Clients, then GTP and S1AP. Of course this does not address LTE as a whole, but they are all critical pieces of the puzzle. These features will allow you to run SSL over an LTE network to measure behavior. Fuzz the eNodeB to oblivion to find problems. Throw security attacks over the LTE network and detect vulnerabilities. And much more.

This, in turn, allows you to evaluate the performance and security of LTE network components by simulating actual LTE protocols at high-speeds and load. And allows you to continuously stress your LTE implementation no matter what version, and there are many, you are working on today.

Personally, I’m really excited about these developments and what it means for our users. With the LTE-based features we will be developing you will be able to run every BreakingPoint application (130+) and every security strike (4,500+ live attacks) over an actual LTE network. And do it with the necessary high-performance and scale of 20 Gbps per blade and 15 million simultaneous users per blade.

This is only the beginning of our LTE support and over the next few weeks you are going to hear more directly from the engineers working on these and other developments. The beauty is, you'll hear it here first. If you have any questions about BreakingPoint LTE support feel free to email me directly, dcox at breakingpoint dot com or leave a comment below.