Analyst Fingers NSN Server for Verizon's 4G Fail

One analyst suggests that the Verizon Wireless 4G Long Term Evolution (LTE) outage was caused by a Nokia Networks element in the IMS system that manages subscriber activity on the network. (See Verizon Investigating LTE Outage.)

Simon M. Leopold of Morgan Keegan & Company Inc. put out a research note Thursday afternoon that suggests that the daylong 4G outage was caused by a server that became unstable under heavy loads:

    Our checks indicate that a team from Verizon and its key vendors including Alcatel-Lucent (NYSE: ALU), Ericsson AB (Nasdaq: ERIC) and Nokia Siemens Networks (NSN) pulled together and came up with a work around over night. Our checks suggest the problem resides deep in the network core and involves difficulties authenticating devices as they attempt to connect to the network. We suspect the overload relates to the HSS, the Home Subscriber Service, which is part of the IP Multimedia Subsystem (IMS). We believe the IMS solution comes from NSN. The infrastructure from Alcatel-Lucent and Ericsson seem as if they are functioning properly.

The HSS server holds all the user information related to preferences, subscriptions, location and authorization needed by the network to manage the subscribers as they move around on the 4G network. It is broadly similar to a Home Location Registrar (HLR) in a 3G network set-up.

Verizon Wireless had no comment when LR Mobile asked about the analyst note on Thursday.

— Dan Jones, Site Editor, Light Reading Mobile

Kevin Mitchell 12/5/2012 | 5:06:26 PM
re: Analyst Fingers NSN Server for Verizon's 4G Fail

The detail isn't there to know for sure, but given the Diameter signaling environment here, this could be a problem that a policy exchange controller (PEC) could solve. Many companies are introducing these new products (including my own) to secure and scale the Diameter signaling environment that is prevalent in LTE and IMS.

One role a PEC plays is load balancing, routing and performing admission control for Diameter, including in front of HSS and PCRF servers.



EyeOfTheNeedle 12/5/2012 | 5:06:24 PM
re: Analyst Fingers NSN Server for Verizon's 4G Fail

Certainly overload control capabilities are not part of the design of an HSS. This applies both to IMS and EPC access. Dozens or hundreds of MMEs can easily flood an HSS in many situations. For EPC access a Policy Exchange Controller layer is able to control signaling overloads from MMEs and protect the HSS. 

comtech3 12/5/2012 | 5:06:11 PM
re: Analyst Fingers NSN Server for Verizon's 4G Fail

Seemed that there were no ball to be dropped in this game because there were no ball! LTE is suppose to be a packet data technology,and as such all the necessary backup servers should be in place.Isn't strange that the network went down despite very few devices that are LTE enabled were on it? The thing is, Verizon and others were in a mad rush to build-out their LTE  infrastructure to prove that it was better than WiMax,but who gets the last laugh? However, in the fulness of time we will see which technology will be laughing all the way to the bank!

marchwu 12/5/2012 | 5:06:04 PM
re: Analyst Fingers NSN Server for Verizon's 4G Fail

doesn't work

alandal 12/5/2012 | 5:05:59 PM
re: Analyst Fingers NSN Server for Verizon's 4G Fail

Some seem to suggest this is just an overload problem. Could it be true? How many LTE users are on VzW?

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