Monday, March 8, 2010

Direct Tunneling Vs Gateway offloading

The Next Generation Mobile Equipment will be very Bandwidth intensive and always hungry due to high demand of Video/voice and triple play services on the move. According to one report a single smart-phone traffic uses requirement is apporx 25-30 times higher than the simple GSM phones!

Due to this increased traffic demands, the Mobile networks and Gateways are being flooded and customers are getting unsatisfactory services.
So whats the solution there,

1. Keep increasing the Gateway hardwares to build up the network infrastructure to the next level.
2. Using the optimization methods, such as Direct tunneling and Gateway offloading.

Purchasing the huge number of network hardwares (GWs) to reach the hardware level infrastructure is really not the solution at all, It will eat up millions of dollars for Network service providers and even not complete, on increasing the number of subscriber it will need the same amount of maintains cost continiously!

So whats next!

Direct Tunneling and Offloading.

Direct Tunneling: The direct tunnel feature enables an SGSN to establish a direct user plane tunnel between the radio network controller (RNC) and a GGSN.
The SGSN functions as the gateway between the RNC and the core network. It handles both
signaling traffic (to keep track of the location of mobile devices), and the actual data packets being
exchanged between a mobile device and the Internet.















Snapshot from 3GPP TR 23.919 version 7

So what actually we are doing with the Direct tunnel, we are bypassing the SGSN to reduce the latency and freeing the SGSN from heavy traffic loads.

Now again here is one question? Does this really solve our problem?, I think a bit but not completely, because when the packtes are reaching directly to the GGSN from lots of RNC simultaneously, its again creating the chaos on the GGSN interfaces.

Then network optimization reached to another level where the SGSN and GGSN are thought to be only for the GTP signaling and PCRF and no data traffic will come up from the GGSN.

This New advancement is the SGSN and GGSN offloading.
In this technique a Offload gateway is been placed in the middle of the RNC and SGSN.
Once the PDP context is activated fromt he GGSN, all the Data traffic will follow from the Offload Gateway!

 So both the RNC and Offload Gateway will talk using the Iu-PS interface and SGSN and GGSN will never be loaded due to data traffic.

I really dont have idea about the security vulnerability in this condition and I suspect its really a security issue in this case because we are just allowing the IP packets without the GTP header to the Internet Core from the radio interface.


Waiting for your comments and suggestions!

6 comments:

  1. Another problem is charging that typically is performed by the GGSN. If you bypass the GGSN it won't see the traffic and cannot charge it.

    ReplyDelete
  2. yeah Markus, that problem is obvious, i dont know how they are handling this thing, but there will some other mechanism to check the charging.

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  3. So are there any 3gpp specs around the SGSN/GGSN offloading concept, or is this just a proprietary implementation by some vendors such as Stoke ?

    Kevin

    ReplyDelete
  4. And what about LI ? How can you intercept at all that traffic?

    ReplyDelete
    Replies
    1. sorry couldn't understand your question! please elarborate in details.

      Delete
  5. Kevin, the offloading methods are not new... it depends on the vendor how do they want to implement that. eg. f5 has the ssl offloading very simplified, main goal is fast and seamless data communication with service providers having less problem handling the data, end user getting much better exprience. you might wana check these specs.
    3GPP TR 43.902
    3GPP TS 23.234

    ReplyDelete

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