Subject: Re: draft-ietf-ospf-ospfv3-update-07.txt : part 2: instance

From: Erblichs <[email-masked]>
Date: Wed, 1 Feb 2006 00:10:48 -0800

Group,

	Three questions/comments dealing with Multiple instances
	with one or more in Standby state. Last few are NITs.

1))))) 2.4  Explicit support for multiple instances per link

"In OSPF for IPv4 this was supported in a haphazard fashion using the
   authentication fields in the OSPF for IPv4 header."

IMO, this generally was done by having two OSPF processes share
the same interface whereby each process generated their own
set of adjs, by xmit/recving hello packetts, xmit/recving all
the OSPF control packets.

To make it as efficient as possible, a "1 to many multiplexor"
was sometimes used for recieving, and reverse for transmiting. So, two
or more processes were ACTIVE simulteneously on the same interface.
To allow this a simple reference count was sometimes used to identify
whether the interface was active.

So, if we do this or

2.4 Explicit support for multiple instances per link

"to have a single link belong to two or more OSPF areas."

Requires BOTH processes's to be ACTIVE on the same interface (we are
referring to V2 haphazard support). Howevever, I am confused with the
two following sections for v3 which seems to contradict this..

3.9  Multiple interfaces to a single link

   In OSPF for IPv6, a router may have multiple interfaces to a single
   link.  All interfaces are involved in the reception and transmission
   of data traffic, but only a single interface sends and receives OSPF
   control traffic.

	"only a single interface sends and receives OSPF control traffic."
	How do both instances have full sets of adjs, LSA exchange, etc?

3.9.1  Standby Interface State

   In this state, the interface is one of multiple interfaces to a link
   and this interface is designated Standby and is not sending or
   receiving control packets.

	"this interface is designated Standby and is not sending or receiving
control packets."
	How does the Standby interface/process recv/xmit LSAs??
		
MultipleInterfacesToLink
      An interfaces on the router has received a hello packet from
      another interface on the same router.  One of the interfaces is
      designated as the Active Interface, and the other interface is
      designated as a Standby Interface.  The Standby Interface
      transitions to the Standby state.

------

So, I am reading that one of my instances has the active interface and
the others a Standby state. But "only a single interface sends and
receives OSPF
 control traffic." 

So, how do I sync my LSDB via DBD packets, and refresh
if my standby interface from one of my other instances
can not send or recieve control packets?????

Are you implicitly stating that all processes with all control packets
will use the same Active interface????

2nd question))))  3.9.1  Standby Interface State

If I believed that you need a Standby state, which I am not 100% sure
because of the above section, Why transistion to down, when the
ActiveDies?

When you have the Event:  MultipleInterfacesToLink with Standby new
State,
why don't you stay in this state "AS LONG AS a Standby is available?
Simply
elect new ActiveInterface as long as a Standby Exists?

Why? In the RFC's state machine Standby's go Down, versus
being promoted MultipleInterfacesToLink in my suggestion

So again when a Interface is in the Standby state, why isn't one of
them promoted to MultipleInterfaces ToLink, if the reference count
is 2 or more. When a Standby transitions to down, the Reference count
should be decremented. If the reference count is 1, then DOWN is
acceptable.

3))))) Grammar : should be plural :^) unless we limit 2 interfaces
				      on the same link.

MultipleInterfacesToLink
      An interfaces on the router has received a hello packet from
      another interface on the same router.  One of the interfaces is
      designated as the Active Interface, and the other interface is
      designated as a Standby Interface.  The Standby Interface
      transitions to the Standby state.

interface is > interfaces are
and the other interfaces are designated as a Standby Interface. 

4)))) I think Moy's address bounces..

5)  A.4  LSA formats

   This memo defines eight distinct types of LSAs. >>>> nine listed

 	    1                   0x2001    Router-LSA
            2                   0x2002    Network-LSA
            3                   0x2003    Inter-Area-Prefix-LSA
            4                   0x2004    Inter-Area-Router-LSA
            5                   0x4005    AS-external-LSA
            6                   0x2006    Group-membership-LSA
            7                   0x2007    NSSA-LSA
            8                   0x0008    Link-LSA
            9                   0x2009    Intra-Area-Prefix-LSA

Mitchell Erblich
------------------

---

From: Acee Lindem <[email-masked]>
Date: Thu, 9 Feb 2006 14:25:16 -0500

Hi Mitchell,

>whether the interface was active.
You still need authentication or some other mechanism to de-multiplex 
packets when the
interface is configured in two separate areas or OSPF instances. Anyway, 
I don't want
to delve too deeping in how it was done is OSPFv2.

>two following sections for v3 which seems to contradict this..
The section below pertains to multiple interface on single link with the 
same interface instance ID.
I'll assure this clear. Based on this, I think most of the other 
questions are out of context.

>	How does the Standby interface/process recv/xmit LSAs??
It doesn't.

>will use the same Active interface????
No - I'm implying that all interfaces pretain to the same OSPF instance 
and area.

>3))))) Grammar : should be plural :^) unless we limit 2 interfaces
Ok.

>4)))) I think Moy's address bounces..
Do you have an updated one :^)?

>            9                   0x2009    Intra-Area-Prefix-LSA
Ok - I'll clarify.

Thanks,
Acee

---

From: Acee Lindem <[email-masked]>
Date: Thu, 9 Feb 2006 15:05:41 -0500

Mitchell,

Acee Lindem wrote:

> interface is configured in two separate areas or OSPF instances. 
> Anyway, I don't want
> The section below pertains to multiple interface on single link with 
> the same interface instance ID.

This is already adequately explained in bullet.

> No - I'm implying that all interfaces pretain to the same OSPF 
> instance and area.
>
>>

Precisely where do you think it is wrong.

>>            9                   0x2009    Intra-Area-Prefix-LSA

Please DO NOT cut'n paste pieces from different parts
of the document out of context. It is clear in the context of the
document, which LSAs are defined and which LSA function codes
are reserved.

Thanks,
Acee