Implementations/suggestions for Multihoming IPv6 for DSL sites

Luigi Iannone luigi at net.t-labs.tu-berlin.de
Mon Apr 11 10:15:59 CDT 2011


On 11, Apr, 2011, at 15:37 , Owen DeLong wrote:

> 
> On Apr 11, 2011, at 6:30 AM, Luigi Iannone wrote:
> 
>> 
>> On 11, Apr, 2011, at 15:17 , Owen DeLong wrote:
>> 
>> [snip]
>>>>> 
>>>>> Doing IPv4 LISP on any kind of scale requires significant additional prefixes which at this time doesn't seem so practical to me.
>>>> 
>>>> 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.
>>>> 
>>>> 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.
>>>> 
>>>> Luigi
>>>> 
>>> Who said anything about BGP? I was talking about the amount of additional IP space needed vs. the
>>> amount of IPv4 free space remaining.
>>> 
>> 
>> Sorry. I misunderstood. 
>> 
>> But can you explain better? Why should LISP require more IP space than normal IPv4 deployment?
>> 
>> If you are a new site, you ask for an IP block. This is independent from whether or not you will use LISP.
>> 
> Sure, but, if you also need locators, don't you need additional IP space to use for locators?

No, those are the IP address that you provider gives to your border router.

> 
>> 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?
>> 
> 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.

Not exactly. You do not need more space. You re-use what you have. 

> 
> 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?
> 
> 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.
> 
> If that's the case, then, I believe it leads to at least some amount of duplicate consumption of
> IP numbers.
> 

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.


>> Or I missed the point again?
>> 
> Or perhaps the complexity of LISP in the details still confuses me, despite people's insistence
> that it is not complex.
> 

IMHO it is very simple. As any new technology  there is just a learning curve to follow, but for LISP it is not steep ;-)

Luigi


> Owen
> 
>> thanks 
>> 
>> Luigi
>> 
>> 
>> 
>>> Owen
>>> 
>> 
> 




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