[144881] in North American Network Operators' Group
Re: wet-behind-the-ears whippersnapper seeking advice on building a
daemon@ATHENA.MIT.EDU (Owen DeLong)
Tue Sep 20 14:57:09 2011
From: Owen DeLong <owen@delong.com>
In-Reply-To: <Pine.LNX.4.61.1109200750300.25015@soloth.lewis.org>
Date: Tue, 20 Sep 2011 11:54:54 -0700
To: Jon Lewis <jlewis@lewis.org>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Sep 20, 2011, at 5:01 AM, Jon Lewis wrote:
> On Mon, 19 Sep 2011, Matthew Kaufman wrote:
>=20
>> On 9/19/2011 6:02 PM, Jon Lewis wrote:
>>> On Sun, 18 Sep 2011, Frank Bulk wrote:
>>>> I should have made myself more clear -- the policy amendment would =
make
>>>> clear that multihoming requires only one facilities-based =
connection and
>>>> that the other connections could be fulfilled via tunnels. This =
may be
>>>> heresy for some.
>>> That's not multihoming.
>>=20
>> Really? Lets try these and see how you do:
>=20
> The ARIN NRPM actually defines it:
>=20
> 2.7. Multihomed
>=20
> An organization is multihomed if it receives full-time connectivity =
from
> more than one ISP and has one or more routing prefixes announced by at
> least two of its upstream ISPs.
>=20
> IMO, "full-time connectivity" would mean a leased line, ethernet, or =
even wireless connection, but not a GRE or other tunnel (which is =
entirely dependent on other connectivity).
>=20
Why would you say that a GRE or other tunnel is not full-time =
connectivity? I have full-time GRE tunnels to two ISPs and they do =
actually constitute multihoming under the ARIN interpretation of NRPM =
2.7.
> i.e. if you have a leased line connection to ISP-A, and a tunnel over =
that connection to ISP-B, and either A or your leased line fail, then =
you're down. That's not multihoming.
>=20
In my case, I have full-time circuits to two entities that provide very =
limited IPv4 services. I use those two connections to route GRE tunnels =
to routers in colocation facilities. My AS consists of the routers in =
the colocation facilities combined with the routers at my primary =
location and the networks to which they are attached. The GRE tunnels =
provide OSPF and iBGP routing to the routers at my primary location and =
my prefixes are anchored on the routers at the primary location. The =
colo routers provide the eBGP border connectivity to the upstream =
routers at each of the colos.
In what way is this not multihoming?
Now, let's look at some alternatives...
If I have only a single router at my primary location, is it still =
multihoming? I would say yes. Perhaps less reliable, but, that is not =
ARIN's concern.
If I have only a single physical link over which the multiple tunnels =
are connected, am I still receiving full time connectivity from two =
providers over the multiple tunnels?
Yes, actually, I am. Again, it's not as reliable, but, reliability is =
not ARIN's concern.
> Some of the scenarios you suggested are pretty unusual and would have =
to be considered on a case by case basis. i.e. a shared T1 to some =
common point over which you peer with 2 providers? I'd argue in that =
case, whoever provides or terminates the T1 in that case is your one =
transit provider, and again, you're really not multihomed...unless its =
your T1 and your router at the remote side, and that router has ethernet =
to the two providers...then that router is multihomed, and though most =
of your network is not, I'd argue that you have satisfied the =
requirement for being multihomed.
>=20
I think you are delving much deeper into the internals of someones =
network than it is customary for ARIN to do in order to pass judgment on =
whether or not it is multihomed.
Owen
