Suggestion for out-of-band IPv6 DHCP server

[Gaston Gloesener]

Glad to hear that the idea is welcome. This is all I could expect at this
time.

 

Ø  OK - I think I understand what you are looking at doing.  We have
considered doing

Ø  something i this area but the priority for doing it hasn't been high.
What we were

Ø  thinking about was to provide a method for a client running on one
interface to

Ø  get a prefix delegation and pass it on to a server running on one more
other

Ø  interfaces.  

 

Ø  Is this the general use case that you are trying to address?  Or is there
some other

Ø  way the interfaces the server is using are getting their addresses (and
subnets).

 

Not exactely. This would be the “normal” in-band case where the router to
the upper network 

(if we consider The network a tree with the internet being the root at the
top) needs to have 

a DHCP server both being able to delegate prefixes and be a statefull DHCP
server. So if the

internet router in first place has no DHCP server functionality or only one
of both my out-of band

suggestion jumps in. 

 

Basically in the IPv6 design the DHCP servers are required to be on the
routers to work correctly.

But what if the router does not have one ?

 

So what you suggest is the correct way in regard of the IPv6 specifications
but does not work if the next 

upper router does not have a DHCP server and thus cannot delegate any
prefixes. Also with that limitation

no other DHCP server can be configured in the local network since the prefix
may change.

 

When it comes to the implementation both in- and out-of-band implementations
will use a lot of code 

in common since basically only the source of the prefix is different.

 

To be more detail about the differences read IB=in-band=PD=prefix Delegation
and OOB=out-of-band, so IB

and PD are the same:

 

Ø  IB==Prefix delegation (paranoia ;-) )

Ø  IB: Get the prefix to use from the DHCP server on the next upper router
(internet router in first place)

Ø  OOB: Extracts the prefix from a configured interface

Ø  OOB: to be used when IB is not available because the upper router has no
PD ability

Ø  OOB: to be used when the router has no state full DHCP server
functionality (or limited) to determine prefix to be used

Ø  IB: delegated prefix to be used on other interface than the one where the
delegation was obtained (the way IPv6 works)

Ø  OOB: prefix to be used on the same interface from which it was extracted

Ø  OOB: configuration may optionally allow to generate additional prefixes
from the one extracted for other interfaces

 

Assuming the prefix delegation mechanism is known I will write up and post
two scenarios to explain where this does not work 

and how OOB DHSCP would operate in these cases. However it is correct that
this is most likely to be a DHCP server not running 

on the internet router so where the client is not directly facing the ISP.
In my case for example the ISP requires me to take some 

fixed router type for him to fully support my connection. But this router
has no DHCP v6 server. But even if it would have one, 

possibly its configuration possibilities would be to limited to use it.

 

I’ll come back soon with these scenarios.

 

 

 

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