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  1. Post
    #1
    Seeing we get the same threads time and time again, please refer to this first before making a thread. Read through the terms so you know what you're talking about when you're saying my DSLAM/RAN etc sucks.

    ADSL
    Asymetric Digital Subscriber Line - asymetric meaning it's faster downstream than upstream.

    ASAM
    Advanced Services Access Manager (also known as Alcatel 7300). This is an older type of DSLAM which is ATM based. Most ASAMs are subtended from another ASAM. They're slowly being replaced with ISAMs. See DSLAM's as well.

    ATM
    Asynchronous Transfer Mode - a method of encapsulation which is capable of many virtual circuits. With these, providers (ISP's) can split an ATM connection (155Mbit or 622Mbit) up into many connections. ATM isn't just used for DSL but in the case of DSL it's used to provision each customer.

    Conklin DSLAM
    Generally in areas where ADSL isn't available, these are subtended from an ASAM. The bandwidth is fairly limited and is shared with all users on the Conklin (this could be up to 60 depending on how many expansions there are). These are slowly being replaced with ASAMs.

    Contention Ratios
    A contention ratio is the number of users to xMbit of bandwidth. In New Zealand I don't know of any providers who publicly advertise their ratio, or who use them, but they are likely to arrive here soon. For example with 2Mbit Telecom DSL, it's 50:1, meaning 50 users to 1Mbit of bandwidth. In countries such as the UK you can buy residential broadband packages and select your contention ratio, the cheaper plans having a higher ratio, and the more expensive plans having a lower ratio.

    CPE
    Customer Premises Equipment, the term that describes the equipment used on the customer end of a connection, for example your DSL modem/router, cable modem, black box on Wired Country etc.

    DSL
    Digital Subscriber Line.

    DSLAM
    Digital Subscriber Line Access Multiplexer - one or more of these are placed in each exchange that has DSL enabled, when your modem syncs up and the DSL light comes on, it means you are connected to the DSLAM. When data travels down your connection, it goes from the CPE -> DSLAM -> RAN -> ISP (or in the case of Jetstream it doesn't go to the ISP and instead goes to Netgate). There are a few types of DSLAMs used in NZ, see ASAMs, ISAMs, Nokia N50s and Conklins.

    ERX
    Edge Routing Exchange. See RAN.

    Login Realm
    The bit after the @ on your username, ie @xadsl.xtra.co.nz or @jetstart.jet.net.nz or @dsl.maxnet.co.nz and so on. If someone asks you to check this then this is what they're asking about.

    IPNet
    Telecom's backhaul network for carrying traffic from the customer to the ISP, ie carrying traffic from RAN's to ISP's.

    ISAM
    Intelligent Services Access Manager (also known as Alcatel 7302). This DSLAM is ethernet based and supports ADSL2+, and in some cases has a hybrid card (NVLT-C cards) which will be able to support VDSL2 for future proofing. These are being deployed in new cabinets/exchanges across the country. See DSLAM's as well.

    LNS's
    L2TP Network Servers - Each (wholesale) ISP has an L2TP Tunnel coming from the Telecom Wholesale handover to carry the PPP sessions - this is the ISP endpoint that would pass the attempts onto the ISP's RADIUS server.

    Nokia N50
    Not as common as ISAM/ASAM and not as advanced. ADSL1 only like an ASAM and your ISP won't be able to check your line remotely. It's basically an ASAM, but it has remote shelves, not subtends. See DSLAM's as well.

    Netgate
    This is primarily used for Go Large/Big Time customers now (13/04/2010). It's set up as a virtual router within all the RAN's around the country. One of Telecom's brands - they provide national/international connectivity.

    Ping or Latency
    Not many people seem to know what a "ping" actually is. A ping measures the time in milliseconds that it takes for a packet to travel from your computer to a remote computer and back to you again. Just because you can't ping a given host - for example Xtra's homepage doesn't mean it's down, quite a lot of providers are beginning to filter ICMP (pings come under this protocol) traffic because it is commonly used to attack hosts and wastes a lot of bandwidth.
    Many providers also give low priority to ping (ICMP) traffic which may mean your ping at a command line isn't very good, but in say a game, things may be fine.

    RAN
    Regional Access Node (not Remote Access Node!). These aggregate many DSLAM's connections and then feed the data to an ISP or to Netgate. Telecom have recently replaced their Nokia Redback RAN's with new Juniper ERX's.

    Realm
    Also known as a login realm.

    RTT
    Round Trip Time - the time it takes in milliseconds for a packet to go from A to B and back again. See ping.

    SDSL
    Symmetrical Digital Subscriber Line - symmetrical meaning the same speed up and down. In New Zealand Telecom is using SDSL to provision new frame relay links where possible as it is much cheaper.

    Units
    Thanks to DaNzA for bringing this up. So many people post using incorrect units. Please please please learn the correct units.

    THE DIFFERENCE BETWEEN UPPER AND LOWER CASE:

    MB = MegaBytes
    Mb = Megabits
    kB = KiloBytes
    kb = Kilobits

    MB/s = MegaBytes per second
    Mb/s = Megabits per second
    kB/s = KiloBytes per second
    kb/s = Kilobits per second

    1kB = 8kb
    256kb = 32kB/sec

    1MB = 1024kB
    1Mb = 128kB/sec

    2Mb = 256kB

    If you're unsure, then specify the FULL TERM in your post, ie I have a 2Mbit connection, don't say 2MB - that implies you have a 16Mbit connection.

    Wireless
    Contrary to what people seem to think - wireless does not suck. Wireless can ping very nicely depending on the technology used and again the contention ratio the provider uses. Examples of nice wireless connections are Wired Country with their 3.5GHz gear and those providers using things like 2.4GHz (802.11b), 5.3GHz (802.11a) and 5.8Ghz. Woosh uses another technology, WCDMA for their wireless - however it appears the pings are high on it, whether this is related directly to WCDMA or just Woosh's implementation I'm not sure yet - but in exchange for a poor ping time you can hurtle down the motorway at 100km/h and keep using the internet. It is worth noting that 2.4Ghz WISP's are more susceptible to interferance issues than WISP's operating in the 3.5Ghz and 5.x Ghz frequencies.

    I did type this all up pretty quickly so there could be errors - please PM me if there are and I'll fix them, don't tear my head off/call me a newbie.

  2. Post
    #2
    FAQ's

    Most important of all, the moment your DSL dies, DON'T race to call your ISP's helpdesk! Any sane ISP if not all have monitoring systems in place that will notify them of most problems. Chances are they know already - calling them and wasting their time telling every customer the same thing over and over is counter productive. It makes more sense to just wait until they have sorted the problem rather than tying up their resources with phone calls when they could be putting more money towards more bandwidth for you to use.

    A good idea is to give things a few hours (ie 2-3 hours) - then if things still aren't going it's probably a problem that's affecting just you or a small number of users, in which case you should then call support.

    I can't authenticate!
    Firstly, make sure you have DSL sync on your modem. If you don't your attempts won't go anywhere. Check your username and password are correct on your modem, if you are on Telecom you only need to make sure a valid Xtra realm is supplied (*@xtrabb.co.nz,*@xtra.co.nz,*@jetstreamgames.co.nz,*@teleco m.co.nz) as the AAA server will authenticate you by the port. If you're sure this is correct check your ISP isn't having network issues and then call them to log a fault.

    I can't resolve anything!
    Your DNS settings are wrong, or your ISP's DNS servers are hosed (not likely). Go into your network properties/connection properties and set your DNS servers to your ISP's. I have posted a few of the more common ISP's DNS servers below. See their website/helpdesk if they aren't listed.

    I can't sync!
    Wait a few hours, there might be an outage, if you _still_ can't sync after about 6 hours give your ISP a call who in turn will call Telecom. Don't waste time calling Telecom, they will just tell you to call your ISP. If your ISP tells you to call Telecom then tell them not to be lazy - they know the rules.

    My DSL is really slow!
    Is it peak time? If so get used to it. With the coming of higher speed plans, contention ratios will become more noticable. If you want better speeds then pay for a business/carrier grade connection. If your speeds are _really_ _really_ slow, like 1-2kB/sec and you've checked your speed against http://jetstreamgames.co.nz/speed and it's slow there too, then there probably is a problem. Usually ISP's are aware that their bandwidth is overloaded, and probably have ordered more so there's no point calling the helpdesk. Just sit tight, and if after a few days your speeds still suck, then you might want to call up. In the case of extremely low speeds even from the JetstreamGames test site, then you should call the helpdesk because your line card is probably dead or some other similar problem.

    My DSL won't work at all!
    Is your DSL light on your modem on? If not see "I can't sync!" If the DSL light is on then it could be either:
    a) Your login isn't working (look in your router/modem settings and find where it tells you if you're logged in or not. If you aren't logged in then see "I can't authenticate!".
    b) If you can login but you cannot browse, it might be a DNS problem. See "I can't resolve anything!"
    If neither of these solve your problem, and you can access your modem okay from your computer, call your ISP helpdesk. If you can't access your modem ie your modem doesn't work, don't call your ISP - this is not their problem. Take it back to wherever you bought it and they can support you.

    My pings suck!
    Telecom's SLA (service level agreement) states you can get anywhere up to 1000ms on a UBS/Bitstream connection and there is no limit to what your ping can be on other plans. Again like the speeds, pings tend to rise when Telecom or your ISP has run out of bandwidth, and if this is the case, then they already will have ordered more. Again don't waste time calling the helpdesk, they'll tell you to send some traceroutes/pings or tell you that there's no problem - ie go away.


    ISP DNS Servers:
    ICONZ: 210.48.65.1 and 210.48.66.1
    Ihug: 203.109.129.67 and 203.109.129.68
    Inspire: 203.114.128.1 and 203.114.128.2
    Maxnet: 123.100.71.1 and 123.100.71.2
    Orcon: 210.55.12.1 and 210.55.12.2
    TelstraClear: 203.96.152.4 and 203.96.152.12
    Xnet: 58.28.4.2 and 58.28.6.2
    Xtra: 202.27.184.3 and 202.27.184.5

  3. Post
    #3
    What are Line Attenuation and Noise?

    Your broadband modem or router will likely have a page in it’s web interface listing your line statistics. These are often used to judge the quality of your line. This page attempts to explain the terms used.


    SN Margin

    (AKA Signal to Noise Margin or Signal to Noise Ratio)

    This is the relative strength of the DSL signal to noise ratio - the higher the number the better for this measurement. 6dB is generally the lowest dB manufacturers specify in order for the modem to be able to sync. In some instances interleaving can help raise the noise margin to an acceptable level. Generally speaking, as overall bandwidth increases, your signal to noise ratio decreases.
    • 6dB or below is bad and will experience no sync or intermittent sync problems
    • 7dB-10dB is fair but does not leave much room for variances in conditions
    • 11dB-20dB is good with little or no sync problems (but see note below)
    • 20db or above is bad, this occurs when the end-user is too close to the phone exchange. If this occurs the user may end up with alot of DSL connections. To reduce this we can place the user on a low noise profile, which does sometimes resolve the issue.

    Note: there may be short term bursts of noise on your line that may drop the margin, but due to the sampling time of the management utility in your modem/router, will not show up in the figures.


    Line Attenuation

    This is a measure of how much the signal has degraded between the DSLAM and your modem/router, and is largely a function of the distance from the exchange (bigger distances mean higher attenuation). Maximum signal loss recommendation is usually about 60dB. The lower the dB the better for this measurement.
    • 20dB and below is outstanding
    • 20dB-30dB is excellent
    • 30dB-40dB is very good
    • 40dB-50dB is good
    • 50dB-60dB is poor and may experience connectivity issues
    • 60dB or above is bad and will experience connectivity issues

    Note: From a user perspective, there very little you can do to change the line attenuation of your current connection.


    DSL Rate ***/tx/rx/Rate

    The actual service ATM data rate that your ISP has provisioned, plus bandwidth to cover the overhead.


    Attainable Line Rate

    (AKA Sync Rate)

    This is the maximum rate at which your modem can connect to the DSLAM if there was no service provisioning limiting the bandwidth. The higher the number the better.


    Output or TX Power

    How much power your modem (upstream) or DSLAM (downstream) is using. Maximum recommended is about 15dB. The lower the power the better for this measurement. Not all modems have the ability to provide output power.


    Occupancy

    Occupancy is the percentage of line capacity used. Each DSL line is capable of a certain maximum speed or “capacity” dependant on line distance and other varying factors. The occupancy is an expression of your current sync rate setting over your maximum capacity. There are occupancy rates for both upload and download. The lower the figure, the better. Because of error correction and other factors in the DSL protocols, a margin is required so that a connection can be maintained under varying line conditions. If the occupancy approaches 100%, any interference can cause the ADSL sync to be lost. A useful measurement to monitor when sync problems occur.


    CRC Errors

    CRC (or Cyclic Redundancy Check) is a method of detecting errors in data transmission. A high CRC count in itself is not really cause for alarm. However, any increase in CRC errors after your initial connection is established is a problem and usually points to a physical issue somewhere between the modem and the DSLAM.

  4. Post
    #4
    Updated 13/04/2010, updated DSLAM definitions and added different types

  5. Post
    #5
    Shade wrote:
    Updated 13/04/2010, updated DSLAM definitions and added different types
    - Hey I might spend some time with you going over the SNR margins etc, this post is from years ago, and some of the info can be corrected, but I will do it up at the same time as I finally fix / overhaul www.adslgeek.com/troubleshooter.