On Tue, 4 Sep 2007, Thomas Bridge wrote:
> Typically the issue with high bandwidth consumers and cost in a
> broadband environment is the impact on the circuits interconnecting
> the Telco
Right... So you're acknowledging the premise - external links are
suffering from contention, even some internal links you say. (And P2P
is /the/ major user of bandwidth, by most accounts).
> The cost of transit is not the most significant cost. And given
> current transit prices,
If I used 'transit' loosely, apologies. I, and the OP (I think),
meant external.
> Yes I have - its irrelevant.
Yet you acknowledge load on external links is becoming a problem?
> You've had a bee in your bonnet for some years about the fact that
> in some situations Eircom took your PPP frame and wrapped it up in
> an IP header to give to your ISP,
Yep. It's far from ideal.
> Unless you're suggesting that all ISPs should run IP to the DSLAM -
> but that's horrendously cost prohibitive compared to the wholesale
> solutions offered by the Telcos.
I'm not a business person, but the current situation is technically
/awful/. If you think otherwise, please agree below to the 'scenic
routing' comment.
A saner model likely would require different business arrangements,
and I can imagine you would disapprove. I recognise the current
arrangements may be entrenched (to a degree). That said, the only
ISPs left in Ireland of note all either own, or are have plans to
expand, significant 'to the curb' networking infrastructure.
(ie unbundled exchanges (Esat/Magnet), fibre to the home (Magnet?),
cable (NTL)).
If the wholesale-DSL-from-state-telco model is as great as you claim
it to be, how come there is no thriving market of reseller-ISPs? Why
is the market converging on a small number of players, each of which
appears keen to control their infrastructure as 'close' to the
customer as they can get?
Even if such a market existed, technically it'd still suck - that'd
be vestigial of the vast bulk of the plant being owned by a former
state-telco, plus IP suckage.
Anyway, no matter the business model: Scenic routing sucks..
(Yes, IPv4 is costly to administrate, IPv6 hopefully less so, but it
still sucks too there. Granted that is a factor).
> If you're going to start blathering on about "native" IP access, you
> need to define what you mean by it. You also need to acknowledge
> that regardless of how it's done, there's a whole bunch of layer 2
> protocols underlying that connection.
I don't have a problem with L2 protocols (like PPP). I have a problem
with encapsulation of layers of L2 protocols over L3 protocols
(L2TP/IP, then again ATM).
> [snip description of the physical topology]
> The whole point of an IP layer is to abstract the physical topology.
> It's the entire point of having a layered networking model.
Urg..
The layered networking model is to abstract the software
/implementation/ of a network stack.
It's NOTHING to do with abstracting interconnections the topology of
nodes in a network. That's quite a unique interpretation, you should
patent it.
> Within that, a number of compromises are typically made based on
> cost.
And politics.
I'll grant IPv4 isn't the most manageable thing though (and I did in
a previous email).
> You will note that even Eircom don't run IP natively in each
> telephone exchange - they backhaul to the regional BAS.
Yes, I know. You must know I know that ;).
That's a choice borne of the present model, a lot of which is to do
with politics.
Do you really, /really/ think the ideal is for Joe and Jack to have
to use bandwidth on the exchange<->BAS, BAS<->ISP and ISP<->ISP
links? If they are exchange neighbours, that traffic (ideally) ought
to be switched at the exchange, otherwise at the BAS..
Are you really saying scenic routing, at least as the result of these
franken-networks of tunneled protocol over tunneled protocol, are a
good thing? :)
> This is a decision made on the grounds of cost - it's much cheaper
> to put a small number of huge boxes in a few key exchanges and
> backhaul the rest of the connections over their ATM network than to
> deploy smaller boxes into each of the exchanges.
Right, no where did I dispute that.
The problem is we're sending packets all around Ireland, when we
could just switch them in one of those huge boxes in (say) Limerick
city exchange..
> You also have better control over traffic allocation and bandwidth
> allocation on a per service basis that way.
Bollocks :)
> The layers of "crap" are there for a good reason - to create
> competition, and to allow the ISPs and the Telcos to offer
> different services to different customers.
Yes, I understand we have to paper over this problem.
That we must suffer this awful organisation of modern, consumer
network provisioning does not make it "good". The best of a bad
situation still sucks. ;)
> The idea that a telco might want to offer a higher quality of
> service to a banks share trading platform than it does to the home
> user downloading a Linux ISO over Bit Torrent is the driver behind
> a huge amount of the development in IP over the last 40 years.
The development has all been under IP, not in IP. We probably /ought/
to have done the development in the IP control plane, rather than
insert entire transports under IP, but we didn't.
So we're stuck with fact that two IP users connected either at same
exchange or same DSL 'BAS', can only communicate via equipment at a
further-hop ISP (or maybe worse, at an even-further-hop IX).
It's just patently obviously that that is less than ideal (aka
'sucks').
> If you're going to descibe something as crap just because it's
> designed to address Layer 8 issues fair enough - I just find it
> ironic coming from a BGP developer.
BGP is a good example...
Note that with BGP, the internet is abstracted as collections of
ASNs, each with it's own internal topology - deliberately abstracted
away by BGP - yet IP (e.g. a packet) still sees the /full/ topology.
Local considerations (at some given hop) can still therefore apply.
We /do/ need to make compromises, to reduce information through
abstraction - but we can do that conceptually in the control plane,
*without* having to abstract the topology of the actual transport.
Abstracting the link-topology because the IP control plane sucks (in
addition to whatever political/competitive considerations there are
around state-telcos) is not good.
And yes, a good part of why that is done is cause IP and BGP suck. It
(like most IP routing protocols) requires manual input of several
magic parameters at each host (arg!), it's pretty complex, it has a
wealth of knobs to tweak.
That doesn't make it good.
Sadly, many in the network-ops community seem to relish the challenge
of IP routing being as difficult as possible, and vendors are happy
to give it to them. Then, due to the complexity, vendors are even
more happy to give network-ops tunneling methods to help deal with
control-plane complexity...
It needn't be so, but hey..
regards,
--
Paul Jakma paul at clubi.iepaul at jakma.org Key ID: 64A2FF6A
Fortune:
You know it's going to be a long day when you get up, shave and shower,
start to get dressed and your shoes are still warm.
-- Dean Webber
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