[79026] in North American Network Operators' Group
Re: T1 vs. T2 [WAS: Apology: [Tier-2 reachability and multihoming]]
daemon@ATHENA.MIT.EDU (Stephen J. Wilcox)
Mon Mar 28 20:23:35 2005
Date: Tue, 29 Mar 2005 02:23:06 +0100 (BST)
From: "Stephen J. Wilcox" <steve@telecomplete.co.uk>
To: John Dupuy <jdupuy-list@socket.net>
Cc: Nanog Mailing list <nanog@merit.edu>
In-Reply-To: <6.0.3.0.2.20050328154404.03701e38@mail.socket.net>
Errors-To: owner-nanog@merit.edu
On Mon, 28 Mar 2005, John Dupuy wrote:
> I'll be brief, but I do want to perhaps word Alex's definition in a diffe=
rent way
> that might be more useful.
>=20
> Even "tier 1" providers regularly trade transit. They must since no singl=
e
> network is connected to all the other ones. Not even close. Even UUNet (A=
SN
> 701), arguably the most-connected network on the planet, only connects to=
a
> fraction of the possible peerings.
701 is not the most connected, it has only customers and a restrictive set =
of=20
peers?
you dont need to peer with all networks tho, if all networks are buying fro=
m 701=20
or one of its peers then it will get those routes via peering not transit o=
r=20
transit trades... you seem to be forgetting what peering is.
and if you peer with all networks in the 'transit free zone' then you too b=
ecome=20
transit free also.
> The true definition is more vague: if a peering or transit circuit betwee=
n A or B
> is taken down, who will be hurt the most: A or B? If it predominantly B, =
and much
> less A, then A is "more Tier 1" and B is of a "lesser Tier". If they are =
equally
> hurt, they the are of equal status. Essentially, "Tier 1" is whatever the=
other
> "Tier 1" providers believe at the moment is "Tier 1". It is self-referent=
ial and
> not distinct at all.
i believe the distinction exists as shown above ie transit free.. as to why=
this=20
might be considered a goal i'm not sure, its not obvious that transit free =
is=20
cheaper than buying transit!
this thing about 'who hurts most' is an entirely different topic and has no=
thing=20
to do with who is in the transit free zone. altho destructive depeering doe=
s=20
seem to be common practice within that zone :)
> This is, frustratingly, a very non-technical definition. But it seems to =
map
> with what I've actually seen the industry do.
thats because non-technical definitions mean anyone can call themselves any=
thing=20
they like.. wiltel recently spammed me to buy their 'tier1 transit'.. presu=
mably=20
they are tier1 within their own definition of tier1.
if you want to be technical tho, and aiui we are a technical forum, then ti=
er1=20
means transit free.
i reaffirm my earlier point - but why care, isnt it about cost and reliabil=
ity,=20
and as peering and transit are about the same cost who cares who you dont p=
eer=20
with
Steve
>=20
> John
>=20
> At 09:17 AM 3/28/2005, Stephen J. Wilcox wrote:
>=20
> On Mon, 28 Mar 2005, Randy Bush wrote:
>=20
> > > Firstly, peering isn't binary. Is peering vs transit a distinct=
ion
> based on
> > > routes taken / accepted & readvertised, or on cost? Does "paid =
for
> peering"
> > > count as peering or transit? If you pay by volume? If you pay f=
or
> "more than
> > > your fair share" of the interconnect pipes? (if the latter, I a=
m
> guessing
> > > there are actually no Tier 1s as everyone reckons they pay for =
more
> than
> > > their fair share...).
> >
> > pay?=A0 did i say pay?=A0 i discussed announcement and receipt of
> prefixes.=A0 this
> > was not an accident.=A0 it is measurable.
>=20
> i also avoided money.. i dont think its that relevant, everyone is
> paying for
> peering or transit in one form or another, i dont think any peering=
is
> free
> (free !=3D settlement free)
>=20
> > > Secondly, it doesn't cover scenarios that have have happened in=
the
> past.
> > > For instance, the route swap. EG Imagine networks X1, X2, X3, X=
4
> are "Tier
> > > 1" as Randy describes them. Network Y peers with all the above
> except X1.
> > > Network Z peers with all the above except X2. Y & Z peer. To av=
oid
> Y or Z
> > > needing to take transit, Y sends Z X2's routes (and sends Z's
> routes to X2
> > > routes marked "no export" to X2's peers), and Z sends Y X1's ro=
utes
> (and
> > > sends Y's routes to X1 marked "no export" to X1's peers). Perha=
ps
> they do
> > > this for free. Perhaps they charge eachother for it and settle =
up
> at the end
> > > of each month. Perhaps it's one company that's just bought anot=
her.
>=20
> "transit (n). The act of passing over, across, or through; passage.=
"
>=20
> whether it is a settlement arrangement or a mutual swap, they do NO=
T
> have
> peering, they ARE transitting and by our definition are not
> transit-free (and
> hence not tier1)
>=20
> however alex, you do highlight an excellent point - things are not =
as
> simple as
> 'tier1, tier2', there are complicated routing and financial
> arrangements in
> operation, which brings me back to my earlier point: does it matter
> what a
> network is paying for some connectivity providing they deliver to y=
ou
> the
> connectivity you need at the quality you desire?
>=20
> Steve
>=20
>=20
>=20
