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Re: draft-ietf-ospf-ospfv3-update-07.txt : instance



Hi Mitchell,
I'm afraid I don't agree with this suggestion either.  See inline.

Erblichs wrote:

Group,

	This is vastly more complicated, so these suggestions
	have been separated from my previous email.

	2.4  Explicit support for multiple instances per link

	"Support for multiple protocol instances on a link is accomplished via
  an "Instance ID" contained in the OSPF packet header and OSPF
  interface data structures.  Instance ID solely affects the reception
  of OSPF packets and applies to normal OSPF interfaces and virtual
  links."

	I like this for brevity, but ...


Summary
-------
The major question is do we consider a instance equal
to a underlying PDB?


I know for a fact that not all OSPF implementations have underlying PDBs :^).

	Verbose
	--------
	It is my understanding is if we want to separate adj's
	based on instance ID that is contained within OSPF
	control packets then we must:
	
	FYI: this list is not complete

* For each set of links on different routers that have matching Instance-ID, we must KEEP the adj's LSAs separate
from other Instance-IDs LSAs.


	* We must be able to group one or more links with
	a area-id and though two area-ids may be equal, they must
	be kept separate because they below to different instances.

	* We must be able to group like Instance-ID areas with
	each other, which I will term a process.

	* Then each instance has one or more areas with one or
	more links, and that can be separately configured as
	a single independent OSPF process,

	* So, each process, must run separately to keep its LSAs
	separate and must each have full OSPF functionality.

* This generates a separate routing domain per instance.


Nope. A "protocol instance" is just that - a separate instance of OSPF with its own
separate set of protocol data structures, state machines, and processes. It usually but doesn't
necessarily imply a separate routing domain. I could add "Protocol Instance" to
section 1.2 if there is any confusion.


Thanks,
Acee

	THEN...... if this is true... My first ROUGH suggested
	change on this subject is...

Support for multiple protocol instances within the OSPFv3
protocol has a 2 part approach. One part is that the
"Instance ID" is contained in the OSPFv3 packet header.
The second part is that each Instance has one or more links that can be shared by other instances. Each
set of interfaces are grouped together into a area and
the set of areas are grouped for normal OSPF functionality.


	Thus, the full set of LSAs recieved per instance are run
	within separate SPF algorithms and each has their own
	set of routing / forwarding tables.

	And each provider can be allocated an instance / separate
	OSPF process on a single router that will support the
	provider's requirements.

	Mitchell Erblich