On Thu, 03 Nov 2011 23:57:15 +0000, David Woodhouse
<(E-Mail Removed)> wrote:
>On Tue, 2011-11-01 at 18:02 +0000, Peter wrote:
>> Where I live and work, in the countryside, where 3G is barely
>> available and GPRS/GSM is very weak, the best thing seem to be to get
>> two analog lines and get two different ISPs to provide a service on
>> these, and have a dual-WAN router.
>
The preferred way to get resilience is to minimise common routes and
paths - if you are in a cabled area then cable + ADSL is likely to
easiest way to protect the "last mile".
Or in the wilds of Scotland etc you may be able to get wireless based
broadband - but most of that was installed in places where normal
broadband coverage is spotty.....
Dual common types of links tends to be much more expensive than just
one
any planner should design the cheapest / shortest access 1st, since
that translates into lower overall cost, and is likely to improve
performance and reliability.
so any 2nd route will need longer cable runs, more new poles + ducts,
and much fewer customers to spread the cost - and you will end up
paying that somewhere in the bill.
>Being in the countryside, you're unlikely to have LLU? So your two links
>to separate ISPs are still going through BT.
FWIW even if LLU is available, you are still using the BT copper from
your location to the same BT exchange.
And since the twisted pairs are out in ducts / hanging from poles,
they are the most susceptible part of the system.
Exactly the same is going to be true of the FTTC and FTTH builds -
there may be some places where new ducts go in so you get separation
from the copper, but given the cost of ducts BT is going to avoid that
when they can.
DSLAMs fitted in a purpose built exchange building with aircon, DC
power and battery backup "should" have a much better protected
environment (apart from the copper lines where interference and spikes
might get into the system).
Then there is the backhaul.
Exchanges are all supposed to have at least 2 BT backhaul cable routes
out. Some ISPs will have their own cables or an OLO fibre pair /
backhaul, but nothing is in place to make your ISP use resilient
backhaul paths (and since that is likely to more than double the
backhaul costs there are some incentives to skimp)
But you may be lucky and 1 of 2 ISPs you pick may have resilient
backhaul and / or the 2 ISPs may not use the same backhaul duct /
cable - but it is going to be difficult to get any checks done about
that.
I'm in a similar situation;
>thankfully my two analogue lines are each connected to a different RAS —
>which helps to avoid a SPOF. They are both with Andrews and Arnold,
>rather than being with different ISPs. It means that I get a whole 2Mb/s
>of combined bandwidth, which is load-balanced across the two lines.
>
>In the absence of 3G (or even reliable 2G) as a backup, I've recently
>joined the FON network (which doesn't require being a BT customer). That
>should mean that if both lines *are* down I can still use a neighbour's
>BTFON access point, make an l2tp tunnel to A&A and still have access to
>my home range of IP addresses, albeit more slowly.
If you get a JCB moment on the duct between you and the exchange it is
likely to hit a duct also feeding other nearby buildings - the duct
system is largely a tree structure.
>
>For email, my solution is to have boxes "out there" which act as
>first-line MX hosts and do all the spam filtering, then deliver mail
>directly to my server at home. After an outage, all I need to do is
>flush the mail queue on my MX hosts.
>
>As for the ISDN line, now that the two ADSL lines are proving to be
>fairly reliable I'm about ready to ditch mine and use exclusively VoIP.
>I'll set it to fall back to placing calls to the analogue lines when the
>SIP client isn't connected, which should mean we don't miss incoming
>calls even during an outage.
--
Regards
(E-Mail Removed) - replace xyz with ntl
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