Ericsson is this week re-entering the market for DSLAMs with an innovative Ethernet access card that it says will unlock the mass market for DSL services by . DSLAM units are typically located in telephone exchanges or distribution points. They allow for the high-speed transmission of DSL technology. Ericsson’s EDA solution is the most widely deployed IP/Ethernet DSLAM with over 60 contracts globally, utilizing the latest ADSL2+ technology.

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But because it was a truly unusual failure mode, and also just because we care a hell of a lot about such things, we dropped everything to resolve it. So far, updating an ECN to that newer software release has resolved the issue on all customers attached to that affected ECN.

This page was last edited on 25 Octoberat Internode engineers a lot of redundancy and resiliency into its network services. They are boot servers, control nodes, statistical aggregation points, and a number of other things including, also, being the ethernet switches that they appear, at face value, to be. An ECN looks like a 24 port ethernet network switch. As I write this, the network is back to operating in erlcsson normal and stable manner. Archived from the original on Each modem on the aggregation card communicates with a single subscriber’s DSL modem.

Its been extremely fast and reliable. From Wikipedia, the free encyclopedia. Unsourced material may be challenged and removed. A DSLAM may or may not be located in the telephone exchange, and may also serve multiple data and voice customers within a neighborhood serving area interfacesometimes in conjunction with a digital loop carrier.

Articles needing additional references from December All articles needing additional references All articles with unsourced statements Articles with unsourced statements from December Commons erifsson link is on Wikidata.


In response we proactively upgraded another significant proportion of the switches in the entire SA network. The current theory, based on vendor feedback, is that the software fault is a latent, load triggered, memory leak that makes the ECN lose the plot in a manner that corrupts some critical item inside one of the ECN systems — an item that remains corrupted after it is rebooted or power cycled.

In other projects Wikimedia Commons. Typically a single DSLAM aggregation card has 24 ports, dalam this number can vary with each manufacturer.

Ericsson EDN312X IP DSLAM Module

Thursday, April 1st, by Simon Hackett. This has been a complicated week! The DSLAM equipment collects the data from its many modem ports and aggregates their voice and data traffic into one complex composite “signal” via multiplexing.

The failure mode resulted in some downstream 12 port DSLAM modules spontaneously rebooting, and after boot, those modules started complaining of being handed invalid configuration data and commenced another reboot and… so on. Each DSLAM has multiple aggregation cards, and each such xslam can have multiple ports to which the customers’ lines are connected. This modem functionality is integrated into the DSLAM itself instead of being done via an external device like a 20th-century voiceband modem.

Like modern airlines, all the routine causes of breakdowns have largely been engineered away. At that exit, those fibre links are attached to inter-exchange fibre paths, and overall what we construct in most cases is a wide-area ring. Balanced pair cable has higher attenuation at higher frequencies. Last night we saw a few more switches not yet upgraded start to demonstrate the fault.

Please help improve this article by adding citations to reliable sources. Once they caught a cold, they kept it. Therefore, it cannot re-route traffic between multiple IP networks, only between ISP devices and end-user connection points.

Our vendor has subsequently identified a bug that is consistent with our observed outcome, and on their advice, we upgraded to the next revision of the code concerned in which that specific bug had been fixed. What is left, therefore just like the airline situationare the truly unusual failure modes.


RSS feed for comments on this post. During reboot, the DSLAM modules maintain physical line sync to the customer, but obviously data flow stops. User traffic is mostly IP based. This sort of resiliency is at the heart of why these systems are generally just rock solid in practice.

Multiplexing Digital subscriber line. Designing and Deploying Triple-Play Services. Views Read Edit View history.

Digital subscriber line access multiplexer

There is switch hardware, power control hardware, and a linux machine, all inside a small rack-mounted box. Accordingly, through this ring architecture, if there is a loss of any single: This compensation capability also takes advantage of the better performance of ” balanced line ” DSL connections, providing capabilities for LAN segments longer than physically similar unshielded twisted pair UTP Ethernet connections, since the balanced line type is generally required for dslwm hardware to function correctly.

The only thing that has been demonstrated to stop the fault is to upgrade the ECN software to a newer release.

This article needs additional citations for verification. Posted in Broadband by Simon Hackett.

Ericsson EDNX IP DSLAM Module | eBay

It is important to appreciate that the current software release reicsson faulty one was rolled out very carefully as all upgrades normally areand it has been flawlessly for around five months until this fault developed. Ok, so what happened? December Learn how and when to remove this template message. The intention of writing this down is transparency — something we love.