[139518] in North American Network Operators' Group
Re: Implementations/suggestions for Multihoming IPv6 for DSL sites
daemon@ATHENA.MIT.EDU (Owen DeLong)
Mon Apr 11 11:28:04 2011
From: Owen DeLong <owen@delong.com>
In-Reply-To: <6AA59EBF-FCE1-4D04-9F86-171602B9426B@net.t-labs.tu-berlin.de>
Date: Mon, 11 Apr 2011 08:26:32 -0700
To: Luigi Iannone <luigi@net.t-labs.tu-berlin.de>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Apr 11, 2011, at 8:15 AM, Luigi Iannone wrote:
>=20
> On 11, Apr, 2011, at 15:37 , Owen DeLong wrote:
>=20
>>=20
>> On Apr 11, 2011, at 6:30 AM, Luigi Iannone wrote:
>>=20
>>>=20
>>> On 11, Apr, 2011, at 15:17 , Owen DeLong wrote:
>>>=20
>>> [snip]
>>>>>>=20
>>>>>> Doing IPv4 LISP on any kind of scale requires significant =
additional prefixes which at this time doesn't seem so practical to me.
>>>>>=20
>>>>> This is not accurate IMO. To inject prefixes in the BGP is needed =
only to make non-LISP sites talk to LISP sites. Even there you can =
aggressively aggregate, as explained in draft-ietf-lisp-interworking.
>>>>>=20
>>>>> As long as the LISP deployment progress you can even withdraw some =
prefixes from the BGP infrastructure and advertise only a larger =
aggregate in order for legacy site to reach the new LISP site.
>>>>>=20
>>>>> Luigi
>>>>>=20
>>>> Who said anything about BGP? I was talking about the amount of =
additional IP space needed vs. the
>>>> amount of IPv4 free space remaining.
>>>>=20
>>>=20
>>> Sorry. I misunderstood.=20
>>>=20
>>> But can you explain better? Why should LISP require more IP space =
than normal IPv4 deployment?
>>>=20
>>> If you are a new site, you ask for an IP block. This is independent =
from whether or not you will use LISP.
>>>=20
>> Sure, but, if you also need locators, don't you need additional IP =
space to use for locators?
>=20
> No, those are the IP address that you provider gives to your border =
router.
>=20
Right... In addition to my provider independent addresses... That's more =
address space than is required
if I am not using LISP.
>>=20
>>> If you are an existing site and you want to switch to LISP why you =
need more space? you can re-use what you have?
>>>=20
>> Perhaps I misunderstand LISP, but, I though you needed space to use =
for locators and space
>> to use for IDs if you are an independently routed multi-homed site.
>=20
> Not exactly. You do not need more space. You re-use what you have.=20
>=20
Still confused, then. This seems antithetical to what you said above and =
below...
>>=20
>> If you are not an independently routed multi-homed site, then, don't =
you need a set of host IDs
>> to go with each of your upstream locators?
>>=20
>> As I understand LISP, it's basically a dynamic tunneling system where =
you have two discrete,
>> but non-overlapping address spaces, one inside the tunnels and one =
outside.
>>=20
>> If that's the case, then, I believe it leads to at least some amount =
of duplicate consumption of
>> IP numbers.
>>=20
>=20
> No true. I ask for a PI block that I will use as EID-Prefix, then the =
locators are part of the address space of my providers.
> There is no duplication.
>=20
>=20
Right... Ordinarily, without LISP, I get a PI block and use that for EID =
and the routing is based on the
EID prefix. With LISP, the EID prefix is PI and I use additional PA =
resources to do the routing locators.
That's what I meant by duplication. There are additional PA resources =
required on top of the PI in order
to make LISP work.
>>> Or I missed the point again?
>>>=20
>> Or perhaps the complexity of LISP in the details still confuses me, =
despite people's insistence
>> that it is not complex.
>>=20
>=20
> IMHO it is very simple. As any new technology there is just a =
learning curve to follow, but for LISP it is not steep ;-)
>=20
I'd agree with you if it weren't for the fact I keep thinking I just =
about understand LISP and then get told
that my understanding is incorrect (repeatedly).
Owen
> Luigi
>=20
>=20
>> Owen
>>=20
>>> thanks=20
>>>=20
>>> Luigi
>>>=20
>>>=20
>>>=20
>>>> Owen
>>>>=20
>>>=20
>>=20
>=20
