[Autoconf] Summary of topologies and addressing discussed recently

Alexandru Petrescu <alexandru.petrescu@gmail.com> Tue, 03 March 2009 16:06 UTC

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Date: Tue, 03 Mar 2009 17:07:07 +0100
From: Alexandru Petrescu <alexandru.petrescu@gmail.com>
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Subject: [Autoconf] Summary of topologies and addressing discussed recently
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Dear AUTOCONFers,

Recently there was discussion on the mailing list about topologies and 
addressing for AUTOCONF.  Some topologies for AUTOCONF were named and 
classified as:
       -only-MANET
       -MANET-to-Internet and
       -MANET-to-MANET-to-Internet (three or more levels)
       -MANET-to-Internet-to-MANET

Some topologies were pictured in more detail - they're listed below as
a summary.  Some participants seemed to agree on these topologies or
on some of their variations.

A simple topology:

         -----  wifi "adhoc1"  ------  wifi "adhoc2"  -----
        |Host1|---------------|Router|---------------|Host2|
         ----- LL1         LL2 ------ LL3        LL4  -----
               G1                                G4


        "adhoc1" and "adhoc2": 802.11 ESSIDs in "ad-hoc" mode.
                               Each is an IPv6 subnet.
        LL1...4: IPv6 link-local addresses.
                 Self-formed according to rfc2464.
        G1, G4:  IPv6 global addresses, for example
                 2001:db8:1::1/64 and
                 2001:db8:2::4/64
                 Manually assigned, or pre-configured with SNMP
                 or formed according to stateless autoconf rfc4862;
                 the prefixes are advertised by Router in RAs.


A simple topology with Routers:

        -------  wifi "adhoc1"  -------  wifi "adhoc2"  -------
       |Router1|---------------|Router2|---------------|Router3|
        ------ LL1          LL2 -------LL3          LL4 -------
               G1                                    G4

       G1, G4: ?


More details on the simple topology with Routers, /64 prefixes and
/128 addresses:

         -----  wifi "adhoc1"  ------  wifi "adhoc2"  -----
        |Host1|---------------|Router|---------------|Host2|
         ----- LL1    P1   LL2 ------ LL3   P2   LL4  -----
               G1                                G4

        G1, G4:  IPv6 global addresses, for example
                 2001:db8:1::1/128 and
                 2001:db8:2::4/128
                 Manually assigned, or pre-configured with SNMP
                 or formed according to stateless autoconf rfc4862;
                 the prefixes are advertised by Router in RAs.
        P1, P2:  IPv6 global prefixes, for example
                 2001:db8:1::/64 and
                 2001:db8:2::/64
                 Manually assigned, or pre-configured with SNMP.

Connecting it to Internet:

    -----  wifi "adhoc1"  ------  wifi "adhoc2"  --------     /
   |Host1|---------------|Router|---------------|Gatewway|---| Internet
    ----- LL1         LL2 ------ LL3        LL4  --------     \
          G1                                G4


        "adhoc1" and "adhoc2": 802.11 ESSIDs in "ad-hoc" mode.
                               Each is an IPv6 subnet.
        LL1...4: IPv6 link-local addresses.
                 Self-formed according to rfc2464.
        G1, G4: ?


Connecting it to Internet via a Satellite link:

  ------  wifi "adhoc1"  ------  wifi "adhoc2"  -------- Satelite /
|NEMOMR|---------------|Router|---------------|Gatewway|--------Int'net
  ------ LL1         LL2 ------ LL3        LL4  --------  TCA1    \
         G1                                 G4

        LL1...4: IPv6 link-local addresses.
                 Self-formed according to rfc2464.
        G1: address formed by NEMOMR either from RA sent by Router, or
            by DHCPv6 considering Router is a DHCPRelay and Gateway is
            a DHCPServer.
        G4: ?
        TCA: Topologically-Correct Address, for Gateway.  It can be
             manually configured on Gateway, or DHCP, or stateless
             autoconf.



In the multi-hop network below only /64 prefixes are present in
Routers' routing tables, no /128 (host-based) routes:


   -----  wifi "adhoc1"  ------  wifi "adhoc2"  ------- "adhoc3"-----
  |Host1|---------------|Router|---------------|Router2|-------|Host2|
   ----- LL1    P1   LL2 ------ LL3   P2   LL4  -------LL5 P3  LL6---
         G1                                                    G4

           P1, P2, P3: /64 prefixes, such as:
                       2001:db8:1::/64
                       2001:db8:2::/64 and
                       2001:db8:3::/64


Breaking the connectivity:

   -------  wifi "adhoc1"  -----   ????   -----  "adhoc2" --------
  |Router1|---------------|Host1|--/  /--|Host2|---------|Router2|
   ------- LL2    P1     LL1 ---          ----LL6   P2  LL6------
                         G1                   G4

Adding more interfaces of different types:

Router1 and Router2 are out of range. So R1 <--> H2 and H1 <--> R2.
Host1 MUST communicate to Host2, this is critical (live or dead).

     +-------+ wifi "adhoc1" +-------+ wifi "adhoc2" +-------+
     |Router1|>-------------<|Router2|>-------------<|Router3|
     +---L---+ LL1      LL21 +---L---+ LL22      LL3 +---L---+
         |M1                     |M2                     |M3

     "adhoc1" and "adhoc2": 802.11 SSIDs in "IBSS" mode.
     Each IBSS is an IPv6 subnet.

     L: Loopback interface.

     >, <: MANET interface.

     LL1, LL21, LL22, LL3: IPv6 link-local addresses.
        Self-formed according to rfc2464.

     M1, M2, M3: IPv6 MANET local addresses, for example
        FD01:db8::1/128, FD01:db8::2/128 and FD01:db8::3/128.
        Manually assigned, or pre-configured (e.g. with SNMP)
        or formed according to a to be defined [Autoconf for MANETs]
        protocol, with a to-be-defined prefix (e.g. ULA, RFC4193).


Again connecting to the Internet, this time via an Access Router:

                             Internet
                                 |
                                 |
                         +-------+-------+
                         | Access Router |
                         +-------+-------+
                                 |
                                 | | Prefix information
                                 | V
                                 |
     +-------+ wifi "adhoc1" +---+---+ wifi "adhoc2" +-------+
     |Router1|>-------------<|Router2|>-------------<|Router3|
     +---L---+ LL1      LL21 +---L---+ LL22      LL3 +---L---+
         |M1                     |M2                     |M3
         |G1                     |G2                     |G3
                    <-------           ------->
          Prefix information           Prefix information


     G1, G2, G3: IPv6 globally unique addresses, for example
        2001:db8:G:1/128, 2001:db8:G:2/128 and 2001:db8:G:3/128.
        Formed according to a to be defined [Autoconf for MANETs]
        protocol, with the prefix provided by (via) the Access Router.


Adding Multi-homing:

      ---+-------Internet--------+---
         |                       |
         |                       |
+-------+-------+       +-------+-------+
|Access Router H|       |Access Router G|
+-------+-------+       +-------+-------+
         |                       |
         ||Prefix information H  | |Prefix information G
         |V                      | V
         |                       |
     +---+---+ wifi "adhoc1" +---+---+ wifi "adhoc2" +-------+
     |Router1|>-------------<|Router2|>-------------<|Router3|
     +---L---+ LL1      LL21 +---L---+ LL22      LL3 +---L---+
         |M1                     |M2                     |M3
         |G1                     |G2                     |G3
         |H1                     |H2                     |H3
                    <-------           ------->
        Prefix information G         Prefix information G, H
               --------->
               Prefix information H

     H1, H2, H3: IPv6 globally unique addresses, for example
        2001:db8:H:1/128, 2001:db8:H:2/128 and 2001:db8:H:3/128.
        Formed according to a to be defined [Autoconf for MANETs]
        protocol, with the prefix provided by (via) Access Router H.


Effect of some links disappearing:


      ---+-------Internet------
         |
         |
+-------+-------+
|Access Router H|
+-------+-------+
         |
         ||Prefix information H
         |V                     wifi "adhoc1"
         |                   <---------------------------v-------->
  <------|--v---------------------->                     |
         |<-|--------------------v-----------------------|--->
         |  |                    |                       |
     +---+--'+               +---'---+               +---'---+
     |Router1|>-------------<|Router2|>-------------<|Router4|
     +---L---+ LL1      LL21 +---L---+ LL22      LL4 +---L---+
         |M1                     |M2                     |M4
         |H1                     |H2                     |H4

               --------->               --------->
               Prefix information H     Prefix information H


No computer movement, but obstacle mouvement:

(802.11 term: STA is station)

           +------------------------+   +------------------------+
           |                        |   |                        |
           |           ____STA-B    |   |           ____STA-B    |
           |       ___/      |      |   |       ___/             |
           |  STA-A          |      |   |  STA-A      OBSTACLE   |
           |      '--_       |      |   |      '--_              |
           |          '----STA-C    |   |          '----STA-C    |
           |  OBSTACLE              |   |                        |
           +------------------------+   +------------------------+
                1-1: No hindrance            1-2: B-C blocked

           +------------------------+   +------------------------+
           |                        |   |          O             |
           |           ____STA-B    |   |          B    STA-B    |
           |       ___/      |      |   |          S      |      |
           |  STA-A      OB  |      |   |  STA-A   T      |      |
           |            ST   |      |   |          A      |      |
           |           AC  STA-C    |   |          C    STA-C    |
           |         LE             |   |          LE            |
           +------------------------+   +------------------------+
                1-3: A-C blocked         1-4: A-B & A-C blocked

                 MANET Scenarios with blocking obstacle


Compare with this one:

(802.11 term: AP is access point)

           +------------------------+   +------------------------+
           |                        |   |                        |
           |           ____STA-B    |   |           ____STA-B    |
           |       ___/             |   |       ___/             |
           |   AP-A                 |   |   AP-A      OBSTACLE   |
           |      '--_              |   |      '--_              |
           |          '----STA-C    |   |          '----STA-C    |
           |  OBSTACLE              |   |                        |
           +------------------------+   +------------------------+
                4-1: No hindrance            4-2: No hindrance

           +------------------------+   +------------------------+
           |                        |   |          O             |
           |           ____STA-B    |   |          B    STA-B    |
           |       ___/             |   |          S             |
           |   AP-A      OB         |   |   AP-A   T             |
           |            ST          |   |          A             |
           |           AC  STA-C    |   |          C    STA-C    |
           |         LE             |   |          LE            |
           +------------------------+   +------------------------+
            4-3: A-C & B-C blocked         4-4: All blocked

              802.11 BSS L2 topology with blocking obstacle


|HAving them pictured, may I ask you: do you think anything will ever be
|able to communicate through Obstacles?


Yes, of course.


           +------------------------+   +------------------------+
           |                        |   |                        |
           |           ____STA-B    |   |           ____STA-B    |
           |       ___/ 1    |      |   |       ___/ 1    .      |
           |  STA-A          | 1    |   |  STA-A    obstacle 5   |
           |      '--_ 1     |      |   |      '--_ 1     .      |
           |          '----STA-C    |   |          '----STA-C    |
           |  obstacle              |   |                        |
           +------------------------+   +------------------------+
                2-1: No hindrance            2-2: B-C degraded

           +------------------------+   +------------------------+
           |                        |   |          o             |
           |           ____STA-B    |   |       5  b ...STA-B    |
           |       ___/ 1    |      |   |       ...s.     |      |
           |  STA-A      ob  | 1    |   |  STA-A  t       | 1    |
           |       ...  st   |      |   |       ...a.     |      |
           |       5  .ac..STA-C    |   |       5  c ...STA-C    |
           |         le             |   |          le            |
           +------------------------+   +------------------------+
                2-3: A-C degraded        2-4: A-B & A-C degraded

                 Scenarios with degrading obstacle


I depicted the metrics: 1 is good, 5 is degraded.

Here the routing tables, with metrics:

       ROUTER   DEST   NEXTHOP METRIC    ROUTER   DEST   NEXTHOP METRIC
      +-------+-------+-------+------+  +-------+-------+-------+------+
      |   A   |   B   |   B   |    1 |  |   A   |   B   |   B   |    1 |
      |       |   C   |   C   |    1 |  |       |   C   |   C   |    1 |
      +-------+-------+-------+------+  +-------+-------+-------+------+
      |   B   |   A   |   A   |    1 |  |   B   |   A   |   A   |    1 |
      |       |   C   |   C   |    1 |  |       |   C   |   C   |    5 |
      +-------+-------+-------+------+  +-------+-------+-------+------+
      |   C   |   A   |   A   |    1 |  |   C   |   A   |   A   |    1 |
      |       |   B   |   B   |    1 |  |       |   B   |   B   |    5 |
      +-------+-------+-------+------+  +-------+-------+-------+------+
           11-1: No hindrance                11-2: B-C is degraded

      +-------+-------+-------+------+  +-------+-------+-------+------+
      |   A   |   B   |   B   |    1 |  |   A   |   B   |   B   |    5 |
      |       |   C   |   C   |    5 |  |       |   C   |   C   |    5 |
      +-------+-------+-------+------+  +-------+-------+-------+------+
      |   B   |   A   |   A   |    1 |  |   B   |   A   |   A   |    5 |
      |       |   C   |   C   |    1 |  |       |   C   |   C   |    1 |
      +-------+-------+-------+------+  +-------+-------+-------+------+
      |   C   |   A   |   A   |    5 |  |   C   |   A   |   A   |    5 |
      |       |   B   |   B   |    1 |  |       |   B   |   B   |    1 |
      +-------+-------+-------+------+  +-------+-------+-------+------+
            11-3: A-C degraded               11-4: A-B & A-C degraded

Alex thanking the participants.