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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This sort of resiliency is at the heart of why these systems are generally just rock solid in practice. Accordingly, through this ring architecture, if there is a loss of any single: Each modem on the aggregation card communicates with a single subscriber’s DSL modem. RSS feed for comments on this post.

A DSLAM may or may not be located in the telephone exchange, and may also serve multiple data and voice customers eicsson a neighborhood serving area interfacesometimes in conjunction with a digital loop carrier. This has been a dsllam week! Internode engineers a lot of redundancy and resiliency into its network services. Dslak 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.

Nodes that have worked flawlessly for five months, so they might work flawlessly for another five months. Customer-premises equipment that interfaces well with the DSLAM to which it is connected may take advantage of enhanced telephone voice and data line signaling features and the bandwidth monitoring and compensation capabilities it supports.

Digital subscriber line access multiplexer – Wikipedia

Unsourced material may be challenged and removed. December Learn how and when to remove this template message. Like modern airlines, all the routine causes of breakdowns have largely been engineered away. 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.

During reboot, the DSLAM modules maintain physical line sync to the customer, but obviously data flow stops. DSLAMs are also used by hotels, lodges, residential neighborhoods, and other businesses operating their own private telephone exchange. In other projects Wikimedia Commons.


There was zero indication of the potential for this to happen, until it started happening this week. Archived from the original on From Wikipedia, the free encyclopedia. This modem functionality is integrated into the DSLAM itself instead of being done via an external device like a 20th-century voiceband modem. 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.

Typically a single DSLAM aggregation card has 24 ports, but this number can vary with each manufacturer. Sorry, the comment form is closed at this time. 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.

The following is a rough guide to the relation between wire distance based on 0. Ok, so what happened? User traffic is mostly IP based.

It also uses the best equipment and services it can obtain — because this is all a part of giving our customers the best possible service experience. The intention of writing this down is transparency — something we love.

Ethernet DSL Access unlocks the broadband mass market

Once they caught a cold, they kept it. In response we proactively upgraded another significant proportion of the switches in the entire SA network. 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.

Posted in Broadband by Simon Hackett. Designing and Deploying Triple-Play Services. It has been, and it remains, a very dspam failure mode, starting with this interesting fact — when things went wrong, rebooting the applicable parts of our equipment did not fix those network elements. 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.

Digital subscriber line access multiplexer

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. This article needs additional citations for verification. But it is much more than that. 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.


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

Balanced pair cable has higher attenuation at higher frequencies. Thursday, April 1st, by Simon Hackett. Some weeks are more complicated than others. What is left, therefore just like the airline situationare the truly unusual failure modes.

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.

Please help improve this article by adding citations to reliable sources. Therefore, it cannot re-route traffic between multiple IP networks, only between ISP devices and end-user connection points. Last night we saw a few more switches not yet upgraded start to demonstrate the fault.

The anatomy of ericssoj complex fault. dslzm

As I write this, the network is back to operating in a normal and stable manner. 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. An ECN looks like a 24 port ethernet network switch.