Subject: [manet] OLSRv2 and DYMO for MANEMO Egress-Egress

From: Alexandru Petrescu <[email-masked]>
Date: Mon, 18 Jun 2007 17:34:56 +0200

Hello MANETers,

I'm still in the process of identifying how the two MANET routing
protocols OLSRv2 and DYMO could be used in the MANEMO topology
egress-egress. I'm writing a section for a certain MANEMO draft about this.

However, I have much difficulty in matching the two protocols precisely
on the MANEMO egress-egress topoology. The problems I have are mostly
that when I read the MANET documents I tend to make remarks to MANET WG
about the inner coherency of the two MANET protocols, and forget the
goal to match them on the MANEMO E-E topology :-) I realize though that
when I make these remarks on MANET I'm not well understood: people may
not appreciate when I write too many questions or when I complain too
much about something MANET - sorry about that.

Thus I think I decided to post only once the entire the set of questions
I have on the MANET list, embedded in the text of MANEMO, and see
whether anyone can help describe how OLSRv2 and DYMO could accomodate
the E-E topology. Thanks for any answer you may have for the embedded
questions.

Alex
------------------------------------------------------------------------
5.  MANET protocols for MANEMO E-E Basic Topology

    In this section we describe the use of two MANET routing protocols
    for the Egress-Egress MANEMO topology.  It is important to identify
    the issues with protocol behaviour in order to either suggest
    improvements to MANET protocols or to motivate the design of
    alternative mechanisms.  There's no selective intention of
    declaring a MANEMO winning protocol among the two MANET protocols
    considered.

    MANET Working Group is currently specifying two routing protocols
    which are particularly adapted to the E-E MANEMO topology:
    Optimized Link-State Routing protocol (OLSRv2 []) and Dynamic MANET
    On-demand (DYMO) Routing []).  The two protocols fit largely within
    at least three conceptual distinctive classifications: 'pro-active'
    vs. 'on-demand', 'reactive' vs. 'table-driven' and 'link-state' vs
    'distance-vector' respectively.  For example DYMO is known as a
    on-demand table-driven distance-vector protocol whereas OLSRv2 the
    others.

    In the E-E basic topology it is assumed that two moving networks
    are deployed in two vehicles respectively.  The two moving networks
    have an IP prefix (MNP) assigned to the hosts (LFN).  Each moving
    network is not pre-configured with the IP address of the egress
    interface or the MNP of the other router; however, applications on
    LFN1 know the IP address of LFN2 either by static configuration or
    by dynamic acquisition from DNS.  While the two networks can be
    pre-configured locally with IPsec keys and certificats, a network
    has no knowledge of another network's IPsec key.  Once the two
    vehicles are in radio range the hosts of each vehicle need to
    communicate directly.  The discussion is limited to IPv6 only, not
    IPv4.  LL1 and LL2 are the IPv6 link-local addresses of the two
    egress interfaces of Mobile Routers MR1 and MR2.

    For LFN1 connections to the IP address of LFN2 to be succesful
    there is a need for each MR to (securely) learn the IP address of
    the other MR and to (securely) distribute the MNPs among the two
    routers.

                                     +-----+
                                     |LFN1 |
                                     +--+--+
                          e+-----+i     |
                    LL1 +--| MR1 |------+---
                        |  +-----+   1::/64 (MNP)
                        |
                        | e+-----+i  2::/64 (MNP)
                    LL2 +--| MR2 |------+---
                           +-----+      |
                                     +--+--+
                                     |LFN2 |
                                     +-----+

    For each MANET protocol we try to identify:

    -is a router periodically sending out route messages?  are messages
     sent in response to solicitations?
    -are default routes being taken into account?
    -what are the MANET protocol message contents?
    -how are the neighbor's IP addresses learned?
    -can a router initiate a route discovery process on behalf of a
     host attached to it?
    -what are the security aspects taken into account by the respective
     protocol (are keys assumed as pre-shared?  are certs used?  is
     IPsec recommended?  arelink/app-layer security tools recommended
     instead of network-layer?  are new security mechanisms
     developped?)?

5.1 DYMO and E-E Basic Topology

    The main contribution of DYMO to routing technology is the
    'on-demand' building of routes; this means that the establishment
    of application data flows between two end nodes (e.g. TCP three-way
    handshake) is preceded by eventual IP route message exchange and
    creation of routing table entries at intermediary routers.  Current
    routing technology is actually not trying to build routes when
    application data packets have no route to follow - these packets
    are simply dropped (and eventually ICMP Destination Unreachable is
    sent.)

    The protocol consists of three UDP messages: Route Request, Route
    Response and Route Error (RREQ, RREP and RERR), sent to a
    link-local scoped multicast address.  Sequence numbers are used for
    avoiding routing loops.  Routes in the routing table have timers
    associated such that routes exist only during a certain lifetime.

                                          MR1            MR2
                                           |              |
                                           |--MLD-REPORT->|
                      +-----+              |<-MLD-REPORT--|
                      |LFN1 |              |              |
                      +--+--+              |-----RREQ---->|
           e+-----+i     |                 |<----RREP-----|
     LL1 +--| MR1 |------+---              |              |
         |  +-----+   1::/64               |<----RREQ-----|
         |                                 |-----RREP---->|
         | e+-----+i  2::/64 

     LL2 +--| MR2 |------+--- 

            +-----+      |                 MR1            MR2
                      +--+--+               |              |
                      |LFN2 |               |--MLD-REPORT->|
                      +-----+               |<-MLD-REPORT--|
                                            |              |
                                            |-----RREP---->|
                                            |<----RREP-----|

    -is a router periodically sending out route messages?  are messages
     sent in response to solicitations?

    Behaviour is as follows: periodically send RREQ and thus receive
    RREP; or periodically advertise RREP.

    -are default routes being taken into account?

    "If a default route exists in the forwarding table, and the router
    were not configured to do anything special based on the information
    in the packet (e.g. src/dst, etc), the packet could be forwarded
    without performing route discovery."

    -what are the MANET protocol message contents?

    RREQ followed by RREP: the RREQ should contain nothing; the RREP
    should contain the MNP and the src link-layer address.

    Periodic RREP: should contain the MNP and the src link-layer
    address.

    The hoplimit should be 1.

    -how are the neighbor's IP addresses learned?

    How?

    -can a router initiate a route discovery process on behalf of a
     host attached to it?

    "DYMO specifies that the Mobile Router should build routes when it
    receives LFNs application data for which it has no routes.  "

    -what are the security aspects taken into account by the respective
    protocol (are keys assumed as pre-shared?  are certs used?  is
    IPsec recommended?  are link/app-layer security tools recommended
    instead of network-layer?  are new security mechanisms
    developped?)?

    The DYMO document demands the use of Authentication Header for
    RREQ, RREP and RERR messages.  However, the document does not
    describe in detail the position of the AH header for IPv4 and IPv6
    cases (can it be simply deduced?).  Also the protocol does not
    describe the necessity of Encapsulating Security Payload, nor the
    dynamic use of keys for IPsec purposes (DYMO assumes keys are
    shared among all MANET members).

    Additional DYMO question: what is the 'distance-vector' in this E-E
    case?

5.2 OLSRv2 and E-E Basic Topology

    The main contribution of OLSRv2 to routing technology is the
    establishment of partially valid routes and the use of multi-point
    relays (MPRs).  This means that...

    The OLSRv2 protocol consists of two UDP messages: HELLO and TC
    (Traffic Control) transmitted periodically.  There is no
    request/response semantics (messages are not sent in response to a
    request, they're only advertised periodically and unsolicited).

                                          MR1            MR2
                                           |              |
                                           |--MLD-REPORT->|
                      +-----+              |<-MLD-REPORT--|
                      |LFN1 |              |              |
                      +--+--+              |-----TC------>|
           e+-----+i     |                 |<----TC-------|
    LL1  +--| MR1 |------+---
         |  +-----+   1::/64
         |
         | e+-----+i  2::/64
    LL2  +--| MR2 |------+---
            +-----+      |                 MR1            MR2
                      +--+--+               |              |
                      |LFN2 |               |--MLD-REPORT->|
                      +-----+               |<-MLD-REPORT--|
                                            |              |
                                            |-----HELLO--->|
                                            |<----HELLO----|

    -is a router periodically sending out route messages?  are messages
     sent in response to solicitations?

    Periodically send TC or periodically send HELLO; no means to have
    solicited responses.

    -are default routes being taken into account?

    No.

    -what are the MANET protocol message contents?

    TC: should contain the MNP and the src link-layer address.  Can it?

    HELLO: it should contain the MNP and the src link-layer address.
    Can it?

    The hoplimit should be 1.

    -how are the neighbor's IP addresses learned?

    Don't know.

    -can a router initiate a route discovery process on behalf of a
     host attached to it?

    Don't know.

    -what are the security aspects taken into account by the respective
     protocol (are keys assumed as pre-shared?  are certs used?  is
     IPsec recommended?  arelink/app-layer security tools recommended
     instead of network-layer?  are new security mechanisms
     developped?)?

    The OLSRv2 document (Appendix G) assumes keys are pre-shared among
    MANET members.  It also recommends the use of application-level
    security (such as pgp ; the document also lets think that
    link-layer security should be used (instead of explicitely
    recommending network-layer security); document recommends IPsec AH
    and sometimes a digital signature sent as a separate OLSRv2 TLV TC
    message.

    Additional OLSRv2 question: what is the 'link-state' in the E-E
    case?  what is the MPR?

5.3 Acknowledgements

    Several aspects exposed in this section have been discussed
    publicly or privately with Charles Perkins, Ben McCarthy, Ryuji
    Wakikawa, Pascal Thubert, Thomas Clausen, Ian Chakeres and Teco
    Boot.

______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please visit http://www.messagelabs.com/email 
______________________________________________________________________

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