Subject: [nemo] RE: Issue 6

From: Vijay Devarapalli <[email-masked]>
Date: Mon, 14 Jul 2003 10:47:41 -0700

hi Pascal,

> > -----Original Message-----
> > 
> >     When the Mobile Router and the Home Agent exchange routes
> >     through routing protocol updates, the Home Agent MUST NOT
> >     create routes to the Mobile network when the Binding Update
> >     from the Mobile Router is received. The Mobile Router also
> >     MUST NOT include any prefix information in the Binding Update.
> >     Any routes to the Mobile Network are created at the Home
> >     Agent through routing protocol updates.
> 
> Why should that be? We can configure routers to use different routing
> protocols at the same time. You need to state how routes are
> redistributed afterwards but this is business as usual. 

I agree with you here.

> It is up the the
> HA config to accept it or not, 

isnt it redundant to include prefix information in the
binding update if routes are being exchanged through a
dynamic routing protocol?

> but I do not see why Nemo should
> interfere with that. 

because NEMO is the one specifying including prefix 
information in the Binding Update. and the NEMO protocol
includes HA creating routes based on this prefix 
information. we are specifying a protocol operation
here.

> There's no need for the protocol operation to place
> such a limit. Do I miss something?

well, you want the protocol to be efficient, right?
when a dynamic routing protocol is being used, including
prefix information in the binding update is both 
redundant and involves an overhead in terms of the size
of binding udpate.

Vijay

---

From: "S. Felix Wu" <[email-masked]>
Date: Wed, 16 Jul 2003 02:15:24 -0700

A couple questions related to the relationship between prefix BU and
routing protocol exchanges between MR and HA:

> dynamic routing protocol?

In regular router configuration, we have static configured routes
and routes learned dynamically from routing protocols such as RIP
or OSPF. They both exist in the regular routers. Aren't the prefixes
being announced via BU under NEMO like static routes in the regular
world, while we at the same time have dynamic routes for other
prefixes using the MR (from the HA point of view)?

It seems to me that this is a configuration/operation issue.

While I agree that the option in discussion (having both BU and
dynamic routing updates for prefixes between a particular pair of
HA and MR) may be redundent, I wonder in practice whether there
are scenarios that we have to have both?

> redundant and involves an overhead in terms of the size

I have actually a question regarding the prefix table, which in
NEMO the HA will use it to check if the MR has the right/ownership
to announce the prefix. First, I assume that, for both BU and dynamic
routing updates, the HA has to check the table before accepting a
route/binding of MR to prefixes. Second, the content of the prefix
table should be maintained correctly by the system administrators.
(This process is actually a tricky one in some cases.)

According to the current drafts, it seems to me that it is possible
that two different MRs can be allowed to announce the same prefix (e.g.,
169.237.6/24):

	prefix table:
	169.237.6/24			MR1, MR2

Or, maybe more interestingly, MR1 will announce a more specific prefix
(e.g., 169.237.6/25) to HA, and the HA should be OK with it.
Therefore, it is possible while MR1 is authorized to own 169.237.6/24,
it actually only has a smaller portion of it (169.237.6/25) at a
particular moment of time. That is why we might need dynamic routing
protocol to reflect that change.

Is that right? (just try to get clarified....)
Thanks.
-Felix

-- 
----------------------------------------------------------------------
Dr. S. (Shyhtsun) Felix Wu                           [email-masked]
Associate Professor                      http://www.cs.ucdavis.edu/~wu
Computer Science Department                     office: 1-530-754-7070
University of California at Davis               fax:    1-530-752-4767
----------------------------------------------------------------------

---

From: "S. Felix Wu" <[email-masked]>
Date: Wed, 16 Jul 2003 02:15:24 -0700

prefix table:
	169.237.6/24			MR1, MR2

---

From: Kent Leung <[email-masked]>
Date: Thu, 17 Jul 2003 01:14:09 -0700

Hi Felix.

>prefixes using the MR (from the HA point of view)?

I would see the prefixes info as dynamic NEMO route updates.
As Pascal said, there not much difference between two routers
exchanging routes via 2 IGPs and administrative metrics selects
the preferred route.

>It seems to me that this is a configuration/operation issue.

Yes I agree.

>are scenarios that we have to have both?

In practice, not sure why anyone would do this.  But then the base NEMO
should not get into config/operation issue, IMHO, and preclude such 
possibility.
Someone can always dream up some wild scenario where they use functions
that weren't foreseen to solve their problems.

>>prefix information in the binding update is both redundant and involves 
>>an overhead in terms of the size
>>of binding udpate.

I think the base NEMO should be basic and flexible.  Best Practices and 
Informational drafts
may be published in the future based on real world deployments.  Probably 
too early to preclude
anything that is not obviously detrimental to the health of NEMO itself.

Kent

---

From: Kent Leung <[email-masked]>
Date: Thu, 17 Jul 2003 01:14:09 -0700

Hi Felix.

Yes I agree.

Kent

---

From: Vijay Devarapalli <[email-masked]>
Date: Thu, 17 Jul 2003 11:07:02 -0700

> that weren't foreseen to solve their problems.

I dont buy this argument. a protocol specification has to be
tight and exact. I dont see why would need both for the same
prefix.

I disagree characterising this as an "config/operation" issue.

I would agree if the Binding Updates and Routing Protocol
updates carry different prefixes, i.e. if the MR uses a
Binding Update to have the HA create routes for a certain
perfix and it uses a routing protocol update for creating
routes for a different prefix.

Vijay

---

From: Vijay Devarapalli <[email-masked]>
Date: Thu, 17 Jul 2003 11:07:02 -0700

Vijay

---

From: Vijay Devarapalli <[email-masked]>
Date: Thu, 17 Jul 2003 11:21:10 -0700

"S. Felix Wu" wrote:

> route/binding of MR to prefixes. 

no. it is currently used only for checking prefixes in 
the binding updates. we assume routing protocols have 
their own mechanisms to authenticate and authorize 
prefixes.

Pascal in a private email wrote

> My suggestion is to open issue 7 to cover authorization of explicit, and
> to word the fact that we allow but do not control or modify that
> activity of an existing routing protocol on the tunnel.

I agree with him.

> Second, the content of the prefix

note that the prefix table is an optional data structure 
to be used only when you want to prevent a misbehaving 
(but authenticated) mobile router from claiming prefixes 
that actually belong to another mobile router.

if you have another means of checking this (or if you
expect the MR not to misbehave) you dont have to implement
the prefix table.

Vijay

---

From: Vijay Devarapalli <[email-masked]>
Date: Thu, 17 Jul 2003 11:21:10 -0700

I agree with him.

Vijay

---

From: Kent Leung <[email-masked]>
Date: Thu, 17 Jul 2003 14:53:02 -0700

>tight and exact. I dont see why would need both for the same

Hmm.  Original text issue is below.  Not sure if you are assuming
same prefix, which may not be always the case.

>routes for a different prefix.

Yes, the original text was exclusive in which method was used to
update the HA.  Still I don't agree there needs to be any additional
checks.  Again, what is the harm?  The result is still traffic to MNP
are tunneled to the MR.

What about inter-mixing statically configured MNP with BU extensions
or IGP?

This is something that multi-protocol routers deal with since they were
invented.  Why is this such a special case?

Kent

---

From: Kent Leung <[email-masked]>
Date: Thu, 17 Jul 2003 14:53:02 -0700

Kent

---

From: Vijay Devarapalli <[email-masked]>
Date: Thu, 17 Jul 2003 15:58:30 -0700

>     Agent through routing protocol updates.

this was proposed a few days back. the latest 
discussion is at http://people.nokia.net/vijayd/nemo/issue6.txt.

> checks.  Again, what is the harm?  

what is the need? I dont see any.

> The result is still traffic to MNP
> are tunneled to the MR.

*extra* traffic.

> invented.  Why is this such a special case?

didnt follow the argument. my question is why add to 
that? I see that you already have to deal with a lot 
of mechanisms for adding routes. why add yet another 
mechanism when it can used exclusive to the IGP over
the bi-directional tunnel.

Vijay

---

From: Vijay Devarapalli <[email-masked]>
Date: Thu, 17 Jul 2003 15:58:30 -0700

*extra* traffic.

Vijay

---

From: Kent Leung <[email-masked]>
Date: Thu, 17 Jul 2003 16:25:39 -0700

>discussion is at http://people.nokia.net/vijayd/nemo/issue6.txt.

Seems like I've been regurgitating some of the comments that Pascal
had sent.

>  Again, what is the harm?

Stalemate. :)

> > The result is still traffic to MNP

Extra control traffic?  Data traffic is still the same irregardless which 
protocol
sets up the route to MNP.  If it's control traffic, the MR is sending the BU
with extensions and doing IGP.  How is this avoided?

>the bi-directional tunnel.

I'm saying that this is not yet another mechanism.  It's the same
mechanism.  MIP is just another IGP in this context.

Kent

---

From: Kent Leung <[email-masked]>
Date: Thu, 17 Jul 2003 16:25:39 -0700

Stalemate. :)

Kent

---

From: Vijay Devarapalli <[email-masked]>
Date: Thu, 17 Jul 2003 17:14:46 -0700

> with extensions and doing IGP.  How is this avoided?

if MR includes same prefix in both the BU and the IGP
message, then it is extra traffic.

> mechanism.  MIP is just another IGP in this context.

MIP adding prefix routes is a new mechanism. if you 
want to call it an IGP, its fine. but I wouldnt.

anybody else has an opinion on this? this thread is
going nowhere.

Vijay

---

From: Vijay Devarapalli <[email-masked]>
Date: Thu, 17 Jul 2003 17:14:46 -0700

Vijay

---

From: Alexandru Petrescu <[email-masked]>
Date: Sat, 19 Jul 2003 01:18:38 +0200

>>> what is the need? I dont see any.

Puzzled.

>>>> The result is still traffic to MNP are tunneled to the MR.
>>> 
>>> *extra* traffic.
>> 
>> Extra control traffic?  Data traffic is still the same irregardless
>>  which protocol sets up the route to MNP.  If it's control traffic,
>>  the MR is sending the BU with extensions and doing IGP.  How is 
>> this avoided?
> 
> 
> if MR includes same prefix in both the BU and the IGP message, then 
> it is extra traffic.
> 
> 
>>> didnt follow the argument. my question is why add to that? I see
>>>  that you already have to deal with a lot of mechanisms for
>>> adding routes. why add yet another mechanism when it can used
>>> exclusive to the IGP over the bi-directional tunnel.
>> 
> MIP adding prefix routes is a new mechanism. if you want to call it 
> an IGP, its fine. but I wouldnt.
> 
> anybody else has an opinion on this?

Yes.  My personal oppinion is my preference for "implicit" mode and let
the rt protocols manage routes exclusively and not include prefixes at
all in BU.

Someone indicated that MIP might be seen as a rt protocol when it adds
routes.  However, I suspect there are tons of parameters (besides the
prefix itself) that are used by rt protocol messaging, like metrics and
such.  Those paramaters should not be included in the BU's.  And MIP
replicating rt protocol functionality is probably redundant, IMHO.

> this thread is going nowhere.

Depends on where you want it to go.

One might think of sitting and analyzing more, and better describing the
rt protocol - MIP interactions...

Alex
GBU

---

From: Alexandru Petrescu <[email-masked]>
Date: Sat, 19 Jul 2003 01:18:38 +0200

Puzzled.

Alex
GBU

---

From: Vijay Devarapalli <[email-masked]>
Date: Fri, 18 Jul 2003 19:15:01 -0700

> the rt protocols manage routes exclusively and not include prefixes at

Alex and others,

let me phrase the issue better.

the question is should the mobile router be able to 
use both prefix information in the binding update and 
a dynamic routing protocol simultaneously to create 
routes at the HA? or should these two mechanisms be 
used exclusive to each other?

my proposal is

   When the Mobile Router and the Home Agent exchange routes through
   routing protocol updates, the Home Agent MUST NOT create routes to
   the Mobile network when the Binding Update from the Mobile Router
   is received.  The Mobile Router also MUST NOT include any prefix
   information in the Binding Update.  Any routes to the Mobile Network
   are created at the Home Agent through routing protocol updates.

Kent and Pascal argue that this restriction should 
not be there. it is currently possible (according to 
them) to run two IGP protocol at the same time and 
nothing breaks. so there is no reason to have this 
restriction.

my argument is where do you use it? how does the MR 
know which prefix should be sent in the BU and which 
in the routing protocol message? if same prefix is 
sent in both, then it is redundant.

I probably have not listed all the arguments here. 
the entire discussion is at 
http://people.nokia.net/vijayd/nemo/issue6.txt.

Vijay

---

From: Vijay Devarapalli <[email-masked]>
Date: Fri, 18 Jul 2003 19:15:01 -0700

Alex and others,

my proposal is

Vijay

---

From: Ryuji Wakikawa <[email-masked]>
Date: Sat, 19 Jul 2003 21:56:50 +0900

Hi Vijay,

> my argument is where do you use it?

If we say routing procols, which routing protocols do you have in mind?
for example, MANET is also a routing protocol. If specially reactive
protocols such as AODV and DSR are used on MR, MR prefer using BU to
manage MNP with HA. I am not sure if people wants to use AODV on MR, but
the current text limits the use of it.

Does anybody have some other examples??

> how does the MR know which prefix should be sent in the BU and which 

You are right, it is hard to know which prefix should be carried by the
BU or by the routing protocol. An easiest way is just sending same
prefix in both. I don't see big problem to send same prefix in both the
BU and the routing protocol. It is redundant, but it's not so big deal,
isn't it?! 

Isn't some warning enough in the base spec?
This is operation matter unless the NEMO protocol is consistent.

regards,
ryuji

---

From: Ryuji Wakikawa <[email-masked]>
Date: Sat, 19 Jul 2003 21:56:50 +0900

Hi Vijay,

regards,
ryuji

---

From: Alexandru Petrescu <[email-masked]>
Date: Sat, 19 Jul 2003 20:22:40 +0200

> If we say routing procols, which routing protocols do you have in 

There are only a few that are in widespread use, look for those.

> manage MNP with HA. I am not sure if people wants to use AODV on MR,

I first want RIP and OSPF, then the experimentals (which are btw
derivations from the former).

> but the current text limits the use of it.

So the current text forbids AODV and DSR?  I haven't seen that
limitation, could you please more explicit, what's the limitation more
exactly?

Alex
GBU

---

From: Alexandru Petrescu <[email-masked]>
Date: Sat, 19 Jul 2003 20:22:40 +0200

Alex
GBU

---

From: Ryuji Wakikawa <[email-masked]>
Date: Sun, 20 Jul 2003 01:53:12 +0900

> limitation, could you please more explicit, what's the limitation more

You misinterpret here. I said the current text forbids to send MNP in
the BU when MR runs AODV or DSR.
It is OK to use only AODV or DSR to carry MNP to HA, but there might be
some requirement to use NEMO as well to ensure the registration. 
The use of BU might be redundant, but more reliable in some situation.

I want to change the text something like below.

original

suggestion
   When the Mobile Router and the Home Agent exchange routes of specific mobile
network prefixes through routing protocol updates, the Home Agent MUST
NOT create the routes of the mobile network prefixes to
   the Mobile Router when the Binding Update from the Mobile Router
   is received.  The Mobile Router also SHOULD NOT include the mobile
   network prefixes exchanged by routing protocol in the Binding Update.  
The routes of the mobile network prefixes to the Mobile Router SHOULD be
created at the Home Agent through routing protocol updates.

ryuji

---

From: Ryuji Wakikawa <[email-masked]>
Date: Sun, 20 Jul 2003 01:53:12 +0900

original

suggestion

ryuji

---

From: Alexandru Petrescu <[email-masked]>
Date: Sun, 20 Jul 2003 01:10:03 +0200

Ryuji Wakikawa wrote:
>>> for example, MANET is also a routing protocol. If specially 
>>> reactive protocols such as AODV and DSR are used on MR, MR prefer
>>>  using BU to manage MNP with HA. I am not sure if people wants to
>>>  use AODV on MR,
>> 
>> limitation, could you please more explicit, what's the limitation 
>> more exactly?
> 
> 
> You misinterpret here.

Sorry.

> I said the current text forbids to send MNP in the BU when MR runs 
> AODV or DSR. It is OK to use only AODV or DSR to carry MNP to HA,

I think DSR will not put any form of MNP in any form of message (be it
BU or route update).  I mean no prefix, but list of addresses.  So you
come down to AODV only which can be treated from a RIP perspective.

> but there might be some requirement to use NEMO as well to ensure the
>  registration. The use of BU might be redundant, but more reliable in
>  some situation.
> 

Ok...

> original When the Mobile Router and the Home Agent exchange routes 
> through routing protocol updates, the Home Agent MUST NOT create 
> routes to the Mobile network when the Binding Update from the Mobile 
> Router is received.  The Mobile Router also MUST NOT include any 
> prefix information in the Binding Update.  Any routes to the Mobile 
> Network are created at the Home Agent through routing protocol 
> updates.
> 
> suggestion When the Mobile Router and the Home Agent exchange routes 
> of specific mobile network prefixes through routing protocol updates,
> the Home Agent MUST NOT create the routes of the mobile network
> prefixes to the Mobile Router when the Binding Update from the Mobile
> Router is received.  The Mobile Router also SHOULD NOT include the
> mobile network prefixes exchanged by routing protocol in the Binding
> Update. The routes of the mobile network prefixes to the Mobile
> Router SHOULD be created at the Home Agent through routing protocol
> updates.

To me, they both sound good.

Alex
GBU

---

From: Alexandru Petrescu <[email-masked]>
Date: Sun, 20 Jul 2003 01:10:03 +0200

Sorry.

Ok...

Alex
GBU

---

From: Alexandru Petrescu <[email-masked]>
Date: Sun, 20 Jul 2003 01:19:00 +0200

Vijay Devarapalli wrote:
>> Yes.  My personal oppinion is my preference for "implicit" mode and
>>  let the rt protocols manage routes exclusively and not include 
>> prefixes at all in BU.
> 
> 
> Alex and others,
> 
> the question is should the mobile router be able to use both prefix 
> information in the binding update and a dynamic routing protocol 
> simultaneously to create routes at the HA? or should these two 
> mechanisms be used exclusive to each other?

I would say that if Explicit mode, then the two mechanisms should be
exclusive.

> the Mobile network when the Binding Update from the Mobile Router is
>  received.  The Mobile Router also MUST NOT include any prefix 

This sounds good to me as I can understand it.

> Kent and Pascal argue that this restriction should not be there. it 
> is currently possible (according to them) to run two IGP protocol at
>  the same time and nothing breaks.

So maybe they want to give an example.  Kent, Pascal, how can one run
several routing protocols on a machine and nothing breaks?  I suppose
that if one routing protocol adds a route, and another routing protocol
deletes the same route, then some things might break.

Or, maybe this spec should not care at all about routing protocols, and
be entirely silent about how MIP interacts with IGP?

> my argument is where do you use it? how does the MR know which prefix
>  should be sent in the BU and which in the routing protocol message?
>  if same prefix is sent in both, then it is redundant.

I agree with the redundancy aspect.  If the mobile network is made of
several fixed links and several fixed routers, then it makes sense to
run IGP in the mobile network, over the MR-HA tunnel, and in the home
domain.  It is highly redundant to have prefixes both in BU's and in the
rt protocol updates, no?

Alex
GBU

---

From: Alexandru Petrescu <[email-masked]>
Date: Sun, 20 Jul 2003 01:19:00 +0200

Alex
GBU

---

From: Vijay Devarapalli <[email-masked]>
Date: Sun, 20 Jul 2003 22:31:18 -0700

> the current text limits the use of it.

RIPng, OSPFv3 for example.

Vijay

---

From: Vijay Devarapalli <[email-masked]>
Date: Sun, 20 Jul 2003 22:31:18 -0700

Vijay

---

From: Vijay Devarapalli <[email-masked]>
Date: Mon, 21 Jul 2003 10:00:11 -0700

> created at the Home Agent through routing protocol updates.

I am fine with your suggestion. Kent, Pascal?

Vijay

---

From: Vijay Devarapalli <[email-masked]>
Date: Mon, 21 Jul 2003 10:00:11 -0700

Vijay

---

From: "Jongkeun Na" <[email-masked]>
Date: Tue, 22 Jul 2003 20:13:16 +0900

Hello Vijay and all,

I want to clarify again my point about issue 6 because I firstly raised
this issue.
First I've pointed that the basic support protocol doesn't properly work
in case of implicit mode BU and dynamic routing protocol assumed. In the
case that prefix table not properly pre-configurated, HA will reply BACK
error for BU of implicit mode according to last paragraph of section
6.6. I guess this case should be considered as the following choices
which we can do now.
1) Section 6.6 last paragraph additionally describes this case. Already
that commented by Ryuji about using new flag field in the entry of
prefix table. The administrator of HA should mark new field in the entry
mapped with HoA of MR for indicating that the MNP will be set and
managed by any other mechanism e.g. dynamic routing protocol. Therefore,
HA will not send BACK error for implicit mode BU if new flag is set.
2) It should be described in somewhere that MNP allowed to MR should be
set in prefix table by the administration regardless of dynamic routing
protocol used through HA-MR tunnel. And, if the implicit mode allowed
then prefix table must be managed by HA, that must be not optional in
that case. In other words, there is a need to clarify the dependence
between use of implicit mode and usage of prefix table. And, in this
case of using dynamic routing protocol, I think specifying of MNP in
prefix table is redundant.

Am I missing something of this thread? Please correct me.
Otherwise, please consider above cases.

/jongkeun

> From: [email-masked] [mailto:[email-masked]] On Behalf Of
Vijay
> Devarapalli
> Sent: Friday, July 18, 2003 7:59 AM
> To: Kent Leung
> Cc: S. Felix Wu; [email-masked]; [email-masked]
> Subject: Re: [nemo] RE: Issue 6
> 
> Kent Leung wrote:
> 
> >

---

From: "Jongkeun Na" <[email-masked]>
Date: Tue, 22 Jul 2003 20:13:16 +0900

Hello Vijay and all,

/jongkeun

Vijay

---

From: Vijay Devarapalli <[email-masked]>
Date: Tue, 22 Jul 2003 14:02:57 -0700

Jongkeun and others,

there are few things mixed up here...

implicit mode is where the MR assumes the HA knows how to 
figure out the MNP and add routes. the prefix table is a
MUST if an IGP is not used over the bi-directional tunnel.
if an IGP is not being used, and also the prefix table
contains no entries for the MR, then the HA returns a 
Binding Ack with status code 143 (Mobile Network Prefix 
information unavailable).

the prefix table is not needed in case the MR and HA are 
exchanging routes using an IGP. we assume the MR can prove
ownership of prefixes using the IGP.

the prefix table is also used in explicit mode, if the HA 
needs to prevent a misbehaving mobile router from claiming 
MNPs belonging to another mobile router.

Vijay

---

From: Vijay Devarapalli <[email-masked]>
Date: Tue, 22 Jul 2003 14:02:57 -0700

Jongkeun and others,

Vijay