[e2e] [SPAM] - Re: number of flows per unit time in routers -Email has different SMTP TO: and MIME TO: fields in the email addresses

Detlef Bosau detlef.bosau at web.de
Thu Dec 1 06:47:20 PST 2005

Ping Pan wrote:
> Actually, not really. GE and 10GE are getting real popular for access,
> in particular, PON-based access networks. There could be tons of GE/10GE
> at aggregation points, but only a single OC3/OC12 toward the core.

I once got a paper rejected and one of the reviewer comments was why I
the "bottleneck link" in the dumbbell was larger than the "acces links".

Excuse me, I´m aged 42 and I have less hair on my head than when I was
aged 24 and some guys claim they would have seen one or two grey hairs
on my head. So, perhaps this is the reason why I cannot understand why
we use OC/12 links to the _backbone_ and 10 GE networks in the access

It may be that some cable guys convince their customers with this,
excuse me, most likely superfluous stuff but despite of very rare cases
I don´t see a reason to attach a computer to the Internet using a 10 GE

But attaching a network to a _backbone_ using an OC/12 link is perhaps
not that much better.

How many tracks as a highway? One per direction? Or two?

And how many tracks as a lonely lane in Somewherevillage?

Surely 24 per direction.

It may be that a shepherd needs the place for his flock to come home.

Of course, I have admittedly no idea of actual bandwidths in actual
backbone networks. Rarely, some providers here in Germany boast with
"backbone links" 
with OC/12 lines and think this to be somehow attractive. However, I
don´t see whether this really makes sense.

However, I´m willing to learn here, because either way proper bandwidth
planing starts with proper baselining and traffic analysis.

> The assumption has been that video traffic can be handled locally within
> aggregation networks, (R/F overlay through optical links directly, or
> satellite video download etc...)
> What may happened is that large user traffic bursts jam into the narrow
> OC-n links toward the core. This is where proper traffic policing
> becomes useful.

And proper bandwidth planing. I´m by far no expert in fibre links. I
really don´t see a reason why one should waste 10 GE networks
to attach two computers in some office to something and to use OC/12,
i.e. 600 MBit/s, links to attach a network, say a provider network,
to the Internet core.

O.k., perhaps it gives Cisco the opportunity to talk small companies
into buying new routers and interfaces and to waste lots of money
for unnecessary stuff. Honestly, I sometimes did not beleive my eyes
when I saw the overprovisioning which is done in many companies.

One of the topics here is congestion control. When I think of congestion
control in many companies, I ask: Congestion? Control?

When two PCs are interconnected by a series of 10 GE fibres and routers
in between are equipped with 100 GByte of memory each, the Microsoft
will recommend window scaling in order to exploit the ressources...



I´ve rarely seen it _that_ extreme. However, I would not be surprised
when the first "decision maker notebook" is attached to the company LAN
using a 1 Terabit/s line, because otherwise a decision maker would not
be able to make decisions.

O.k., when two notebooks in a decision maker´s office are interconnected
via a satellite link, 10 GBit/s may suffice....

> - Ping
> Clark Gaylord wrote:
> >
> > The other thing you need for that to work is that core link speeds are
> > faster than access speeds, but with that assumption it doesn't take long
> > to get to this conclusion.
> >
> > --ckg

Detlef Bosau
Galileistrasse 30
70565 Stuttgart
Mail: detlef.bosau at web.de
Web: http://www.detlef-bosau.de
Mobile: +49 172 681 9937

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