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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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The intention of writing this down is transparency — something we love. A digital subscriber line access multiplexer DSLAMoften pronounced DEE-slam is a network device, often located in telephone exchangesthat connects multiple customer digital subscriber line DSL interfaces to a high-speed digital communications channel using multiplexing techniques. This article needs additional citations for verification. User traffic delam mostly IP based. Typically a single DSLAM aggregation card has 24 ports, but this number can vary with each manufacturer.

Posted in Broadband by Simon Hackett. Internode The Web Search Search. 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. As I write this, the network is back to operating in a normal and stable manner.

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

Based on vendor advice, we are now looking at how best to upgrade the rest of the network, to guard against a further recurrence elsewhere. Retrieved from ” https: There is switch hardware, power control hardware, and erkcsson linux machine, all inside a small rack-mounted box. Some weeks are more eficsson than others. Balanced pair cable has higher attenuation at higher frequencies. It is important to appreciate that the current dskam release the faulty one was rolled out very carefully as all upgrades normally areand it has been flawlessly for around five months until this fault developed.


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Ericsson EDN312X IP DSLAM Module

What is left, therefore just like the airline situationare the truly unusual failure modes. The only thing that ericson been demonstrated to stop the fault is to upgrade the ECN software to a newer release. RSS feed for comments on this post. But it is much more than that.

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. By using this site, you agree to the Terms of Use and Privacy Policy. This sort of resiliency is at the heart of why these systems are generally just rock solid in practice.

December Learn how and when to remove this template message. Unsourced material may be challenged and removed. Sorry, the comment form is closed at this time. Archived from the original on An ECN looks like a 24 port ethernet network switch. In other projects Wikimedia Commons. This is due to the nominal line impedance measured in Ohms but comprising both resistance and inductance of balanced lines being somewhat lower than that of UTP, thus supporting ‘weaker’ signals however the solid-state electronics required to construct such digital interfaces are more costly.

This page was last edited on 25 Octoberat 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.

The anatomy of a complex fault.

InterComms – The International Communications Project

Once they caught a cold, they kept it. This is not a trivial decision, because we are upgrading to a new software release — which brings in the potential for there to be some other, as yet unknown, issue for our service. From Wikipedia, the free encyclopedia.


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 its hardware to function correctly.

Therefore, it cannot re-route traffic between multiple IP networks, only between ISP devices and end-user connection points. Like traditional voice-band modems, a DSLAM’s integrated DSL modems are usually able to probe the line and to adjust themselves to electronically or digitally compensate for forward echoes and other bandwidth-limiting factors in order to move data at the maximum possible connection rate. This modem functionality is integrated into the DSLAM itself instead of being done via an external device like a 20th-century voiceband modem.

Designing and Deploying Triple-Play Services. Ok, so fricsson happened?

So far, updating an ECN to that newer software release has resolved the issue on all customers attached to that affected ECN. Its been extremely fast and reliable. We obviously had a fault. 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.

It has been, and it remains, a very unusual failure mode, starting with this interesting fact — when things went wrong, rebooting the applicable parts of our equipment did not fix those network elements.

A Sslam 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.