[Techtalk] High speed access question
Raven, corporate courtesan
raven at oneeyedcrow.net
Wed Oct 3 03:00:01 EST 2001
Quoth Kath (Wed, Oct 03, 2001 at 12:34:18AM -0400):
> - Would it be best to get every building a unique run to a Tier1/2 provider (decentralized)? I'm against it, I'd rather have all lines run to one central district location and then out. It would be easier to firewall and administrate than having 18 firewalls in 9 locations.
It really depends on what you need as far as redundancy and
uptime guarantees. Tier 1 providers are big, yes, but many of them will
charge you more precisely because they are Tier 1. (And many
marketroids will claim that their provider is Tier 1 without any
conception of the actual meaning of the term. For those of you not in
networking, a Tier I provider is one that doesn't have to buy transit
from any other network.) It's worth investigating all the available
competitors in your area.
Are you looking at dual lines from the main office out to the
Internet? If not, you'll be isolated if/when your line drops. And
depending on who your regional LEC is and what sort of SLA (Service
Level Agreement -- basically your contract with your provider), it could
be days before you're up again. If this is not acceptable, negotiate a
2 or 4 hour turnaround time with your provider, or invest in redundant
If possible, get your two main lines from different providers,
or have them follow separate physical paths. That way, a failure in one
(fiber cut, for example) is less likely to take out the other one as
well. Redundancy doesn't do you much good if the circuits follow the
same path and terminate in the same router on the far end.
Will you be managing your own routers, or having the providers
do it for you? If you are using multiple providers, you may have to do
it yourself, since there's usually a "nobody touches this but us" clause
in there for managed care.
> - What kind of provisioning in terms of bandwidth should there be on the line? A T1 connect (1.544 Mbps) from each school to the main location (the HS)? What about from the HS to the internet?
It honestly depends on how many folks you expect to be using the
Net at any given time. If I were you, I would go for T-1's off a
channelized T3, so that the actual run to your buildings is a T3, and
you're just using 1/28th of it. The provisioning costs are usually not
that different, and it makes upgrading later easier. Mention to
whatever provider you select that you may want to upgrade these lines
later -- they will recommend the easiest solutions for you from their
You may also want to consider Frame Relay, ATM, or some other
technology that can be configured to let you burst traffic during
periods of high usage, but get generally charged for a lower bandwidth
connection. If you go with Frame Relay, make sure to ask what the CIR
is. The CIR (committed information rate) is your guaranteed throughput.
Many companies will try to sell you a circuit with a CIR of 0. Do not
buy from them unless your budget is very low -- they're taking your
money and guaranteeing you nothing.
> When a "T1" line is installed, how hard is it to upgrade it to more bandwidth? Does it require plant facility changes (putting down new fiber or copper) or is it merely a change in the Criscos on both ends? (I'm not saying going from fractional T1 to OC3+, but from T1 to T3 speeds).
It totally depends on how they provision it in the first place.
If you're part of a channelized T3, it's a thirty second config change
on the routers. If you're not, you may be in for all the charges you
originally encountered. Discuss this with your provider salespeople.
> Would it perhaps be wiser to have the capacity for a large line (say, 45 Mbps), but negotiate with the provider so that the school would only use what is paid for on a month to month basis? (This works out in the summer when noone is there and therefore the internet is not used)
Might be worth it -- compare prices for that vs. full T1's.
Mention at first that you don't really know what your bandwidth usage is
going to be like, and that you would like to be flexible about
increasing it. And then once your lines are up and running, install
MRTG on your handy Linux server to keep track of utilization. This is
particularly useful in cases of billing disputes with a usage-based
> - Also, what about multihoming? A few local schools here were knocked offline following Sept 11th, as the West Street telecom hub was damaged, but customers connected to 60 Hudson Street facilities were fine.
True multihoming (to 2 different providers) may be overkill for
you. It requires you to have your own AS (autonomous system) number,
and your own IP block to route. Some providers won't accept a BGP
announcement for anything smaller than a /24. Some won't accept
anything smaller than a /19. If you're a basement multihomer, you may
have problems getting your announcements heard. Your best bet may be to
have 2 T3s to different routers in one provider. That way, you get your
IP space from them, and you can just use a private AS number (analogous
to using 10.0.0.0 for your machines -- it gets translated into the
"real" AS number of your provider when it leaves their network.)
Feel free to ask questions if any of this is unclear.
"There shall be nine companions, to match the nine riders that
-- Gandalf the Grey, in a humorously emphasized audio version
of Tolkien's "Lord of the Rings"
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