Subject: RE: [manet] Gateway address resolution

From: "Manfredi, Albert E" <[email-masked]>
Date: Mon, 1 Jul 2002 10:06:47 -0400

Mullen, John P. wrote:

> Hi,
> 
> I know I'm missing something here.
> 
> Why can't the MANET be treated as a local intranet with each 
> of its nodes
> having a common Internet subnet mask (augmented by whatever 
> is needed to
> affect routing within the MANET, of course.)  When a gateway 
> sees a packet
> bearing an IP with the MANET subnet mask, it knows it is 
> intended for a node
> within the MANET, while one with a different pattern would be clearly
> intended for the Internet.

Because that wouldn't be the general solution. Seems that many want to be able to turn on their MANET host anywhere and have it join the MANET, without needing DHCP or other server, and without having to enter a MANET-specific IP address and mask manually. And the host must be capable of roaming freely.

If you expect the MANET hosts to belong to a particular IP subnet, that mandates some sort of manual or automatic IP address/mask configuration, with the requisite changes as the host roams.

Bert

_______________________________________________
manet mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/manet

---

From: "Mullen, John P. (Contractor)" <[email-masked]>
Date: Mon, 1 Jul 2002 07:47:32 -0600

Hi,

Why can't the MANET be treated as a local intranet with each of its nodes
having a common Internet subnet mask (augmented by whatever is needed to
affect routing within the MANET, of course.)  When a gateway sees a packet
bearing an IP with the MANET subnet mask, it knows it is intended for a node
within the MANET, while one with a different pattern would be clearly
intended for the Internet.  

John Mullen

-----Original Message-----
From: Yasser A. Lotfy [mailto:[email-masked]]
Sent: Friday, June 28, 2002 3:40 PM
To: [email-masked]; Kuldip Singh Pabla; Charles E. Perkins; Rex
Buddenberg
Cc: [email-masked]
Subject: [manet] Gateway address resolution

Hi,

Seems like many have agreed on the general ideas in my original e-mail.
However, one point yet need further discussion:

Gateway address resolution; 
Since ad-hoc IP addresses don't represent a pool of addresses, the idea of
subnet mask can not be used. Hince, distinguishing intranet traffic from
internet traaffic becomes a critical challenge.

For example ad-hoc gateways can read distination address and check againest
table of all ad-hoc IP addresses. This can raise scalability issues. Can
IPv6 provide a way to distinguish local ad-hoc nodes from fixed structure
nodes? Any other ideas?

Yasser 
Carleton U
Ottawa, Canada

____________________________________________________________
Win a first-class trip to New Orleans and vacation Elvis Style!.
Enter NOW!
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---

From: "Mullen, John P. (Contractor)" <[email-masked]>
Date: Mon, 1 Jul 2002 09:00:21 -0600

Hi Bert,

Well, at least in some MANETs, there is an attempt to introduce hierarchical
routing through dynamic clustering.  These are the organization-related
MANETs (military, public services, etc.) though, rather than the open-ended
ones that are more general.

The proliferation of the Internet and local networks may eventually lead to
a reform of the whole IP approach.  For example, we may end up with 40 or
48-bit IP addresses in a few years, something like the move from five-digit
to nine-digit zip codes.  The demand is very great and, with today's
technology, the extra bits are relatively cheap.  

Another technological fix on the horizon is the use of GPS data.  Rental
cars now routinely come with GPS receivers.  The ability to receive and
decode GPS could become a standard MANET feature.  Someone will probably
come up with routing and clustering schemes based on that GPS info.  That
could really help routing in those wide-open general MANETs.

On the other side, I hear that someone has invented a RF-blocking paint that
many theater and restaurant operators are interested in.  (I wonder how that
will fly the first time someone needs to dial 911 from within a structure
coated with this paint).  I suspect there will be sociological, as well as
technological, aspects to the eventual use of MANETs.

After all, Jazz musicians manage, why not MANETs?

:-)

As for the hop-by-hop, that is not really unusual.  It just appears that way
because of the differences in clustering and channel availability and usage
in MANETs, as opposed to wired nets.  In both cases, nodes are not smart
enough to figure out what to do with a packet on their own, so each packet
is either constrained, through selection of a point-to-point channel, or
addressed so that the recipient is not in doubt.  This is usually managed at
the lower levels, so IP can seem less messy, but the hop-by-hop routing is
still there. 

John Mullen

-----Original Message-----
From: Manfredi, Albert E [mailto:[email-masked]]
Sent: Monday, July 01, 2002 8:25 AM
To: 'Mullen, John P. (Contractor)'
Subject: RE: [manet] Gateway address resolution

You're most welcome, John.

Actually, I don't see much similarity between a MANET and anything
IP-related, as we have known IP to be until now. MANET seems to operate a
lot more like a Layer 2 catenet, i.e. a big, multi-hop infrastructure with
no attempt at hierarchical addressing and routing. It's quite chaotic. And
no one seems to worry too much about scaling.

For example, routes have to be described hop by hop. Not exactly the way IP
is supposed to work.

Bert

> From: Mullen, John P. (Contractor)
> [mailto:[email-masked]]
> Sent: Monday, July 01, 2002 10:17 AM
> To: Manfredi, Albert E
> Subject: RE: [manet] Gateway address resolution
> 
> 
> Thanks Bert,
> 
> I was thinking of a situation in which all MANET nodes would have an
> association with a common organization, such as in area 
> emergency relief.  I
> can see, however, the problem in the more general case you describe.
> 
> JPM
> 
> From: Manfredi, Albert E [mailto:[email-masked]]
> Sent: Monday, July 01, 2002 8:07 AM
> To: 'Mullen, John P. (Contractor)'; [email-masked]
> Subject: RE: [manet] Gateway address resolution
> 
> 
> Mullen, John P. wrote:
> 
> > Hi,
> > 
> Because that wouldn't be the general solution. Seems that 
> many want to be
> able to turn on their MANET host anywhere and have it join the MANET,
> without needing DHCP or other server, and without having to enter a
> MANET-specific IP address and mask manually. And the host 
> must be capable of
> roaming freely.
> 
> If you expect the MANET hosts to belong to a particular IP 
> subnet, that
> mandates some sort of manual or automatic IP address/mask 
> configuration,
> with the requisite changes as the host roams.
> 
> Bert
>

---

From: "Mullen, John P. (Contractor)" <[email-masked]>
Date: Mon, 1 Jul 2002 09:00:21 -0600

Hi Bert,

:-)

John Mullen

-----Original Message-----
From: Manfredi, Albert E [mailto:[email-masked]]
Sent: Monday, July 01, 2002 8:25 AM
To: 'Mullen, John P. (Contractor)'
Subject: RE: [manet] Gateway address resolution

Bert

---

From: "Manfredi, Albert E" <[email-masked]>
Date: Mon, 1 Jul 2002 13:35:44 -0400

Charlie Perkins wrote:

> Finally,
> the node can use its pre-existing IP address (not topologically
> correct) for bidirectional Internet communications, but in
> that case it has to use Mobile IP.

Charlie,

I think that even this limitation is not mandatory, as we discussed last week. In principle, if the Internet gateways to the MANET and the MANET hosts conduct ICMP Router Discovery (RFC 1256), and if the gateways maintain a complete list of all MANET hosts, as if the MANET host IP addresses were just arbitrary flat addresses, then MANET hosts should be able to conduct bidirectional Internet communications without going to Mobile IP.

The gateways would sort of operate like NATs, except that the MANET side is a flat address space. That's why the gateways need the exhaustive list of all MANET hosts.

Bert

---

From: "Yasser A. Lotfy" <[email-masked]>
Date: Mon, 01 Jul 2002 13:33:44 -0400

Hi,

Your e-mail holds many interesting ideas. It clearly raises the need to understand why MANET should not rely on a pool of contiguous IP addresses.

1) Nodes should be able to roam freely in the network. If a cellular node connected to the cellular network via address xxxx came into accessable range of a bluetooth MANET based network, it might decide to join. Obviously, the node prefer to keep its xxxx address.

2) Imagine the situation when you have many MANET networks scaterd in somewhat geographically limited area. Every network will be able to adminstrate itself (ie assign contiguous IP addresses, and subnet mask). Those MANET networks will have occasional interference in shared areas (areas that may belong to more than one MANET). Shared areas obviously have dynamic nature. Nodes roaming from one MANET network to the next should be able to do so without giving up it's IP address.

3) The use of anytype of DHCP requires adminstration both at the node level, and centralized level. In addition, centralized management of MANET contradicts it's charter.

4) Users are entitled to have thier own IP addresses. Assume my PDA address is yyyy, and it is a static IP that is recognizable throughout the internet. Part of the IPv6 effort is to allow personal IP addresses. Overiding this address contradicts with IPv6 directions.

However, I understand that having a pool of contiguous addresses may be the common case. Yet, building the network should be based on the more general case.

Comments?

Yasser

---

From: "Manfredi, Albert E" <[email-masked]>
Date: Mon, 1 Jul 2002 13:50:56 -0400

Hi Charlie,

In the case I described, the MANET host would have to transmit first. Similar to the situation you have today with DHCP and IEEE 802.11 nets in "infrastructure mode."

If the MANET host initiates the session, then the fixed Internet host will see the IP address assigned to the MANET host by the MANET gateway at that time.

I agree that if you want Internet hosts to initiate the session with the MANET host, without any prior knowledge, then Mobile IP would be required.

Bert

Charlie Perkins wrote:

> Hello Bert,
> 
> In the case you describe, what address does a host in the Internet use
> as the destination address, to connect with the manet node?
> 
> "Manfredi, Albert E" wrote:
> 
> > Charlie Perkins wrote:
> >
> > > Finally,
> > I think that even this limitation is not mandatory, as we 
> discussed last week. In principle, if the Internet gateways 
> to the MANET and the MANET hosts conduct ICMP Router 
> Discovery (RFC 1256), and if the gateways maintain a complete 
> list of all MANET hosts, as if the MANET host IP addresses 
> were just arbitrary flat addresses, then MANET hosts should 
> be able to conduct bidirectional Internet communications 
> without going to Mobile IP.
> >
> > The gateways would sort of operate like NATs, except that 
> the MANET side is a flat address space. That's why the 
> gateways need the exhaustive list of all MANET hosts.
> >
> > Bert

---

From: "Manfredi, Albert E" <[email-masked]>
Date: Mon, 1 Jul 2002 13:50:56 -0400

Hi Charlie,

Bert

---

From: "Mullen, John P. (Contractor)" <[email-masked]>
Date: Mon, 1 Jul 2002 12:34:18 -0600

Mulling on this,

Suppose we had a MANET implementation of a "cellular" phone system, in which
instead of a backbone of cellular antennas, routers, etc., there is just a
few isolated antennas designed to act as gateways to the internet.

Of course, the handsets would differ from the usual cellular handset in that
it would be able to forward packets for other users and might also be
strictly digital, with limited digital voice, to compensate for the limited
bandwidth.

The question is, how will a user entering the region of a local MANET be
properly identified and make its location known to other hosts, including
those access through the Internet.

My thought is this:

Suppose there were on the Internet a number of special servers whose
function is to provide directory service for this class of users.  Each
mobile host would have a unique identifier (IP?) that would be easily
associated with a subset of these servers, much like area code gives us an
idea of what state the user is in.  However, this is just to simplify the
task of finding an entry and has nothing to do with the host's current
association or location.

Whenever a host comes within range of one of the associated MANETs, it
recognizes, through Hello messages, the proximity of like hosts and
broadcasts its own request to join.  Once the local group accepts its
membership, it unicasts a location packet to one of the Internet gateways,
which keeps this information for its own use, but also forwards to the
appropriate directory server the host's IP as well as the gateway's own IP.
Then, any host accessing through the Internet, trying to find the mobile
host in question, would request directory assistance, finding whatever
information it needs to route packets to the gateway.

Technically, I realize, this is a form of centralized information storage,
but it is for the purpose of locating a particular host that may be on any
one of hundreds of MANETs, or on none.  The storage is on the Internet, not
on the MANET.  Local MANET routing information would not be forwarded, so
the directory entry would be valid (and useful) as long as the host is in
that particular MANET, even if the route to it within the MANET changes. 

John Mullen

---

From: "Manfredi, Albert E" <[email-masked]>
Date: Mon, 1 Jul 2002 14:44:41 -0400

John,

How does what you describe differ from Mobile IP?

In Mobile IP, the job of the home server is to keep track of where the mobile host pops up at any given time. In the basic version of Mobile IP, all packets to and from the mobile host are routed through the home server. In a newer elaboration, the actual current address of the mobile host is provided to the host wanting to communicate with the mobile host, so the home server can be bypassed.

If I understand your proposal, doesn't this meet the same functionality?

Bert

> Sent: Monday, July 01, 2002 2:34 PM
> To: Manfredi, Albert E; 'Charlie Perkins'
> Cc: [email-masked]

---

From: "Manfredi, Albert E" <[email-masked]>
Date: Mon, 1 Jul 2002 14:44:41 -0400

John,

Bert

---

From: "Mullen, John P. (Contractor)" <[email-masked]>
Date: Mon, 1 Jul 2002 13:13:36 -0600

Hi Bert,

Well, my idea is similar to the newer elaboration of Mobile IP, except
possibly that the information provided by the server is just a vector to one
of the MANET's gateways, not the full address.

In Mobile IP, as I understand it, the vector is to a fixed host that is in
direct communications with the mobile host.  However, in my idea, the vector
is just to the MANET.  All details of interconnection within the MANET are
hidden from the Internet.  This should decrease the volatility of the
listing.

Also, it could be possible to have the server operated as a stand-alone
directory service, not affiliated with a particular MANET or type of host.
Users wishing such connectivity could subscribe to the service, while others
could forego the option, independently of which organization or MANETs they
belong to.

The one down side I see is that unless users insist on privacy from the
beginning, there would be a new option open to telemarketers.

:-/

John Mullen

-----Original Message-----
From: Manfredi, Albert E [mailto:[email-masked]]
Sent: Monday, July 01, 2002 12:45 PM
To: 'Mullen, John P. (Contractor)'
Cc: [email-masked]
Subject: RE: [manet] Gateway address resolution

John,

In Mobile IP, the job of the home server is to keep track of where the
mobile host pops up at any given time. In the basic version of Mobile IP,
all packets to and from the mobile host are routed through the home server.
In a newer elaboration, the actual current address of the mobile host is
provided to the host wanting to communicate with the mobile host, so the
home server can be bypassed.

Bert

---

From: "Mullen, John P. (Contractor)" <[email-masked]>
Date: Mon, 1 Jul 2002 13:13:36 -0600

Hi Bert,

:-/

John Mullen

-----Original Message-----
From: Manfredi, Albert E [mailto:[email-masked]]
Sent: Monday, July 01, 2002 12:45 PM
To: 'Mullen, John P. (Contractor)'
Cc: [email-masked]
Subject: RE: [manet] Gateway address resolution

John,

Bert

---

From: "Mullen, John P. (Contractor)" <[email-masked]>
Date: Wed, 10 Jul 2002 08:12:28 -0600

Hi Phil,

I've lost the context here, but if I remember right, I was talking about a
way to locate a MANET node from within the Internet.

Martha Steenstrup discusses several clustering schemes in "Cluster-Based
Networks" (Chapter 4 of _Ad Hoc Networking_, by Charles Perkins).  Some of
these clustering schemes would provide a framework in which subnet masks
would work within a MANET.  The idea is that a host is assigned an augmented
IP dynamically according to its location within a hierarchal clustering
framework.  This augmented IP consists of a stable part plus an additional
part that changes as the node moves within the cluster hierarchy.  She
describes a couple of schemes that keep track of these changing augmented IP
addresses.

However, I was not referring to routing within the MANET, but location of
the MANET containing a particular node from within the Internet.  If the
MANET interfaces with the Internet, there will have to be one or more
gateways interconnecting the two.  One wishing to locate the MANET node will
have to find these gateways.  By having all nodes, including the gateways,
have a common internet mask, then the Internet node can locate the MANET as
if it were any other local intranet.  The subnet identification would be
redundant within the MANET, as is the case with any intranet, but may still
be carried as part of the fixed (Internet compatible) portion of the node's
IP.

As far as MANET protocols go, unless the subnetting plan is to be carried
out within the MANET, i.e. as in clustering, there is no need to perpetuate
the bits within the MANET.  The gateway can append the bits to any IP
leaving the MANET for the Internet, but if the bits are the same for all
MANET members, there is no need to include them within the MANET.  However,
I believe most MANET protocols do employ the IP in some way, even if they do
not employ subnetting.  If that is the case, the common bits will simply be
treated as part of the IP, without using any subnet mask.

I think so, anyhow.

:-)

John Mullen

-----Original Message-----
From: Phil Neumiller [mailto:[email-masked]]
Sent: Wednesday, July 10, 2002 7:50 AM
To: Mullen, John P. (Contractor); [email-masked]
Subject: Re: [manet] Gateway address resolution

Hi John,

> affect routing within the MANET, of course.)  

Because all current MANET algorithms are classful in the sense that the
routing
algorithm does not propagate subnet bits masks.  How do you define a subnet
in
a MANET?  I have pondered this for quite some time.  The only reasonable
answer
I have currently is to elect a subnet leader and make the neighbors of the
leader
the subnet.  Maybe the neighbors neighbors too.  When a node gets to far
(too 
many hops away) from a subnet leader and sees a closer one it can acquire
that
subnet mask.  Of course all the MANET protocols would need to change to 
support mask propagation.  This would take some work.

---

From: "Mullen, John P. (Contractor)" <[email-masked]>
Date: Wed, 10 Jul 2002 08:12:28 -0600

Hi Phil,

I think so, anyhow.

:-)

John Mullen

-----Original Message-----
From: Phil Neumiller [mailto:[email-masked]]
Sent: Wednesday, July 10, 2002 7:50 AM
To: Mullen, John P. (Contractor); [email-masked]
Subject: Re: [manet] Gateway address resolution

Hi John,

---

From: "Manfredi, Albert E" <[email-masked]>
Date: Wed, 10 Jul 2002 10:42:56 -0400

John,

I guess the point I was trying to make some time ago is that what the _general_ solution to what you are talking about here is not to depend on some special IP prefix/mask for each MANET host, since this would require some sort of DHCP-like auto configuration service, or static configuration, at the MANET host. Since there is a desire in MANET to allow hosts to keep using their own IP addresses and NOT have to depend on configuration servers, your solution would not be the general one.

My initial suggestion was that gateways keep an exhaustive list of every MANET host, treating these hosts' IP addresses as flat addresses (like MAC addresses in a switched Ethernet), and then use an address translation function when going to and from the Internet. The exhaustive list of all MANET hosts would permit gateways to know whether a packet in the MANET was destined to some MANET host, or to the Internet. While this should work in a client-server model, because the client initiates all transactions, Charlie Perkins responded that this would not work if Internet hosts tried to reach a MANET host without prior knowledge.

His answer has been to use Mobile IP (MONET). In this case, the MANET-Internet gateway could be the foreign agent. A MANET host coming on line would register with this foreign agent, and the MANET host's home agent keeps track of which foreign agent is currently responsible for reaching that MANET host. See RFC 2002. With this approach, and gateways keeping that list of MANET hosts to know whether packets are to be routed or kept inside the MANET, I think all problems should be solvable.

Bert

---

From: "Manfredi, Albert E" <[email-masked]>
Date: Wed, 10 Jul 2002 10:42:56 -0400

John,

Bert

---

From: "Mullen, John P. (Contractor)" <[email-masked]>
Date: Wed, 10 Jul 2002 08:56:13 -0600

Hi Phil,

Thanks for the feedback.  A lot of this stuff is new to me and I'm glad to
hear my mullings are not completely insane.

:-)

John Mullen

-----Original Message-----
From: Phil Neumiller [mailto:[email-masked]]
Sent: Wednesday, July 10, 2002 8:13 AM
To: Mullen, John P. (Contractor); Manfredi, Albert E; 'Charlie Perkins'
Cc: [email-masked]
Subject: Re: [manet] Gateway address resolution

Hi John,

> few isolated antennas designed to act as gateways to the internet.

Check out www.meshnetworks.com.  We have built this system.  We call our
gateways, Intelligent Access Points (IAPs).

> those access through the Internet.

What we do, is allow the MANET algorithm to extend to the IAPs.  The
IAPs can route anyway they want on the backside.  This bridges our MANETs
with the global Internet quite nicely.

> task of finding an entry and has nothing to do with the host's current

I don't think you really need any kind of special server, unless its a 
Mobile IP agent!!!  Mobile IP does what your suggesting here quite
nicely BTW.

> information it needs to route packets to the gateway.

All it has to do is do a MIP handover between the MANETs.

> that particular MANET, even if the route to it within the MANET changes. 

MIP agents don't have to be centralized, except for the home agent that can
be easily be made redundant, i.e. the only stateful host.  The FA is
eliminated
in IPv6 with colocated COA.

You are mulling something that has been done for quite some time by MIP!

Thanks,

Phil

---

From: "Mullen, John P. (Contractor)" <[email-masked]>
Date: Wed, 10 Jul 2002 08:56:13 -0600

Hi Phil,

:-)

John Mullen

-----Original Message-----
From: Phil Neumiller [mailto:[email-masked]]
Sent: Wednesday, July 10, 2002 8:13 AM
To: Mullen, John P. (Contractor); Manfredi, Albert E; 'Charlie Perkins'
Cc: [email-masked]
Subject: Re: [manet] Gateway address resolution

Hi John,

Thanks,

Phil

---

From: "Mullen, John P. (Contractor)" <[email-masked]>
Date: Wed, 10 Jul 2002 08:54:14 -0600

Hi Bert,

I am concerned, as Charlie is, with the problem of how a node within the
Internet locates a host within a MANET, when it knows noting about that
host, except its IP (however that is constructed).  If a host will only
belong to a particular MANET, some sort of subnet address would seem a
logical choice, but if that host could belong to any one of numerous MANETs,
I can see things are far more complex.  The MANETs I work with are of the
first type, but, as you point out, this is not the most general case. 

Thanks for the information.  I'm still learning.

:-)

John Mullen

-----Original Message-----
From: Manfredi, Albert E [mailto:[email-masked]]
Sent: Wednesday, July 10, 2002 8:43 AM
To: 'Mullen, John P. (Contractor)'; [email-masked]
Subject: RE: [manet] Gateway address resolution

John,

I guess the point I was trying to make some time ago is that what the
_general_ solution to what you are talking about here is not to depend on
some special IP prefix/mask for each MANET host, since this would require
some sort of DHCP-like auto configuration service, or static configuration,
at the MANET host. Since there is a desire in MANET to allow hosts to keep
using their own IP addresses and NOT have to depend on configuration
servers, your solution would not be the general one.

My initial suggestion was that gateways keep an exhaustive list of every
MANET host, treating these hosts' IP addresses as flat addresses (like MAC
addresses in a switched Ethernet), and then use an address translation
function when going to and from the Internet. The exhaustive list of all
MANET hosts would permit gateways to know whether a packet in the MANET was
destined to some MANET host, or to the Internet. While this should work in a
client-server model, because the client initiates all transactions, Charlie
Perkins responded that this would not work if Internet hosts tried to reach
a MANET host without prior knowledge.

His answer has been to use Mobile IP (MONET). In this case, the
MANET-Internet gateway could be the foreign agent. A MANET host coming on
line would register with this foreign agent, and the MANET host's home agent
keeps track of which foreign agent is currently responsible for reaching
that MANET host. See RFC 2002. With this approach, and gateways keeping that
list of MANET hosts to know whether packets are to be routed or kept inside
the MANET, I think all problems should be solvable.

Bert

---

From: "Mullen, John P. (Contractor)" <[email-masked]>
Date: Wed, 10 Jul 2002 08:54:14 -0600

Hi Bert,

:-)

John Mullen

-----Original Message-----
From: Manfredi, Albert E [mailto:[email-masked]]
Sent: Wednesday, July 10, 2002 8:43 AM
To: 'Mullen, John P. (Contractor)'; [email-masked]
Subject: RE: [manet] Gateway address resolution

John,

Bert

---

From: "Manfredi, Albert E" <[email-masked]>
Date: Wed, 10 Jul 2002 11:48:13 -0400

> first type, but, as you point out, this is not the most general case.

This is in RFC 2002.

Begin this story with the MANET host, call it Host M, coming on line suddenly in some arbitrary MANET. The first thing Host M does is it figures out if it's home or away. It does so by listening for agent advertisements and/or transmitting agent solicitations. (This protocol is an extensions of the older ICMP router discovery protocol.)

Having found that it is away, and that a "foreign agent" is available, host M then registers with its "home agent" through this "foreign agent." The foreign agent acts only as a passive relay to and from the home agent, in this process.

Host M's "home agent" authenticates this registration request, and now knows which foreign agent in the Internet is currently entrusted with host M. In our case, this foreign agent would be associated with an Internet-MANET gateway. Or it might be part of the gateway.

Let's say an Internet host "I" needs to reach a host M, without knowing where host M is. In general, all host I knows is the address of host M.

The IP packet from host I reaches the "home agent" of host M, simply because the IP DA on that packet routes it through that host M home agent. Host M's home agent knows to intercept any packet addressed to host M, and is keeping track of the current foreign agent servicing host M. This home agent then tunnels the packet meant for host M by encapsulating it in an outer wrapper with the foreign agent's address on it. And the foreign agent forwards it to the MANET host.

The problem of how to reach the MANET host within the MANET remains, of course, since that is not part of Mobile IP. However, Mobile IP does pretty well answer the question of how an Internet host can initiate a session with a MANET host, without knowing where that MANET host is.

I believe that the hosts within the MANET can keep using their own, permanent IP addresses, as we discussed already, as long as the gateways keep a list of every host in their MANET and as long as every MANET packet is routed explicitly, hop by hop, within the MANET (not very scalable, but that's not unusual in MANETs). So I believe that this combination would create a generic solution.

Bert

---

From: "Mullen, John P. (Contractor)" <[email-masked]>
Date: Wed, 10 Jul 2002 10:10:47 -0600

Hi Bert,

While this would work, what goes through my mind is the following scenario.

Suppose Alice and Bill are two EEs from UCLA that are at an international
conference in Prague.  Further suppose, they are trying to communicate with
each other while in two local, but distinct, MANETs.  When Mary sends a
packet to Bill, it will go to his home agent at UCLA, who then wraps it and
forwards it to a gateway on MANET-B, which Bill is using.  In a similar
fashion, packets from Bill also go to UCLA and get forwarded to a gateway on
MANET-A, which includes Alice's computer.  So, two people a few miles from
each other are carrying on a conversation which is being bounced to and from
a location half way around the world.

I don't think this is very far-fetched.  I expect that business and high-tec
travelers will want to use MANET connections to maintain connectivity with
the Internet (and each other).  It also seems logical that their home agents
will be located at their home base.  It also seems logical that two
different hotels might each maintain their own MANETs for the use of their
customers.

I had suggested the directory server approach earlier because with that
approach, the first time Bill sends a message to Alice, his host finds out
from the server the location of the current MANET gateway that can reach
Alice and sends the message directly to that MANET, which then takes care of
getting the message to Alice.  I understand that this capability is in the
latest versions of MONET protocols.  Essentially, the home agent acts as a
directory service, rather than a mail forwarder.  It would seem to be a
better solution.

John Mullen

-----Original Message-----
From: Manfredi, Albert E [mailto:[email-masked]]
Sent: Wednesday, July 10, 2002 9:48 AM
To: 'Mullen, John P. (Contractor)'
Cc: [email-masked]
Subject: RE: [manet] Gateway address resolution

This is in RFC 2002.

Begin this story with the MANET host, call it Host M, coming on line
suddenly in some arbitrary MANET. The first thing Host M does is it figures
out if it's home or away. It does so by listening for agent advertisements
and/or transmitting agent solicitations. (This protocol is an extensions of
the older ICMP router discovery protocol.)

Having found that it is away, and that a "foreign agent" is available, host
M then registers with its "home agent" through this "foreign agent." The
foreign agent acts only as a passive relay to and from the home agent, in
this process.

Host M's "home agent" authenticates this registration request, and now knows
which foreign agent in the Internet is currently entrusted with host M. In
our case, this foreign agent would be associated with an Internet-MANET
gateway. Or it might be part of the gateway.

Let's say an Internet host "I" needs to reach a host M, without knowing
where host M is. In general, all host I knows is the address of host M.

The IP packet from host I reaches the "home agent" of host M, simply because
the IP DA on that packet routes it through that host M home agent. Host M's
home agent knows to intercept any packet addressed to host M, and is keeping
track of the current foreign agent servicing host M. This home agent then
tunnels the packet meant for host M by encapsulating it in an outer wrapper
with the foreign agent's address on it. And the foreign agent forwards it to
the MANET host.

The problem of how to reach the MANET host within the MANET remains, of
course, since that is not part of Mobile IP. However, Mobile IP does pretty
well answer the question of how an Internet host can initiate a session with
a MANET host, without knowing where that MANET host is.

I believe that the hosts within the MANET can keep using their own,
permanent IP addresses, as we discussed already, as long as the gateways
keep a list of every host in their MANET and as long as every MANET packet
is routed explicitly, hop by hop, within the MANET (not very scalable, but
that's not unusual in MANETs). So I believe that this combination would
create a generic solution.

Bert

---

From: "Mullen, John P. (Contractor)" <[email-masked]>
Date: Wed, 10 Jul 2002 10:10:47 -0600

Hi Bert,

John Mullen

-----Original Message-----
From: Manfredi, Albert E [mailto:[email-masked]]
Sent: Wednesday, July 10, 2002 9:48 AM
To: 'Mullen, John P. (Contractor)'
Cc: [email-masked]
Subject: RE: [manet] Gateway address resolution

This is in RFC 2002.

Bert

---

From: "Manfredi, Albert E" <[email-masked]>
Date: Wed, 10 Jul 2002 12:35:24 -0400

John Mullen wrote:

> forwards it to a gateway on MANET-B, which Bill is using.

There used to be an I-D addressing this problem, but I don't see it or an RFC that covers this, in a brief inspection of the Mobile IP wg, and obviously that I-D would have expired long ago. Maybe someone knows what happened to it.

One solution would be for the Bill's home agent to respond back to Alice, or to Alice's default router, when first receiving a packet destined to Bill's host, with Bill's "care-of" address. That way, Alice could transmit packets directly to Bill's current foreign agent.

These shortcuts could equally be relayed back to Alice's own foreign agent, if she is also on the road.

> latest versions of MONET protocols.

I thought it was, but just now I didn't find it. Maybe I should look harder. Anyway, it is doable, I believe, within the context of MONET. This problem was also covered in the wireless ATM wg of the ATMF, years ago.

Bert

---

From: "Manfredi, Albert E" <[email-masked]>
Date: Wed, 10 Jul 2002 12:35:24 -0400

Bert

---

From: "Manfredi, Albert E" <[email-masked]>
Date: Wed, 10 Jul 2002 11:48:13 -0400

This is in RFC 2002.

Bert

---

From: "Fredrik Alriksson (EAB)" <[email-masked]>
Date: Fri, 19 Jul 2002 10:14:25 +0200

Hi Bert,

The solution you describe, plus how the communication between the foreign agent and the MANET host can be done, was published '99 (http://www.e.kth.se/~e94_fal/mipmanet.pdf).

BR,
Fredrik

> Sent: den 10 juli 2002 17:48
> Begin this story with the MANET host, call it Host M, coming 
> on line suddenly in some arbitrary MANET. The first thing 
> Host M does is it figures out if it's home or away. It does 
> so by listening for agent advertisements and/or transmitting 
> agent solicitations. (This protocol is an extensions of the 
> older ICMP router discovery protocol.)
> 
> Having found that it is away, and that a "foreign agent" is 
> available, host M then registers with its "home agent" 
> through this "foreign agent." The foreign agent acts only as 
> a passive relay to and from the home agent, in this process.
> 
> Host M's "home agent" authenticates this registration 
> request, and now knows which foreign agent in the Internet is 
> currently entrusted with host M. In our case, this foreign 
> agent would be associated with an Internet-MANET gateway. Or 
> it might be part of the gateway.
> 
> Let's say an Internet host "I" needs to reach a host M, 
> without knowing where host M is. In general, all host I knows 
> is the address of host M.
> 
> The IP packet from host I reaches the "home agent" of host M, 
> simply because the IP DA on that packet routes it through 
> that host M home agent. Host M's home agent knows to 
> intercept any packet addressed to host M, and is keeping 
> track of the current foreign agent servicing host M. This 
> home agent then tunnels the packet meant for host M by 
> encapsulating it in an outer wrapper with the foreign agent's 
> address on it. And the foreign agent forwards it to the MANET host.
> 
> The problem of how to reach the MANET host within the MANET 
> remains, of course, since that is not part of Mobile IP. 
> However, Mobile IP does pretty well answer the question of 
> how an Internet host can initiate a session with a MANET 
> host, without knowing where that MANET host is.
> 
> I believe that the hosts within the MANET can keep using 
> their own, permanent IP addresses, as we discussed already, 
> as long as the gateways keep a list of every host in their 
> MANET and as long as every MANET packet is routed explicitly, 
> hop by hop, within the MANET (not very scalable, but that's 
> not unusual in MANETs). So I believe that this combination 
> would create a generic solution.
> 
> Bert
>

---

From: "Fredrik Alriksson (EAB)" <[email-masked]>
Date: Fri, 19 Jul 2002 10:14:25 +0200

Hi Bert,

BR,
Fredrik