Re: [Autoconf] Autoconf addressing model

Alexandru Petrescu <alexandru.petrescu@gmail.com> Wed, 04 March 2009 10:13 UTC

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Date: Wed, 04 Mar 2009 11:13:14 +0100
From: Alexandru Petrescu <alexandru.petrescu@gmail.com>
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Subject: Re: [Autoconf] Autoconf addressing model
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Teco Boot a écrit :
> I'll think more on Internet access.

Teco, when I mentioned default routes I didn't think Internet access.  I 
think default routes are good for networks disconnected from the 
Internet too.

> The diagrams were meant for MANET intra topology. I would not use
> private addresses for this. For IPv4, all link addresses could be LL
> also (169.254.0.0/16).

YEs, I think for IPv4 the LL addresses could be 169.254.

> On names in the tables: assume (m)DNS, with A, B and C resolved by it. OK?

Ok if you wish so, with the caveat that DNS does not hold their prefix 
lengths whereas the routing tables do and the prefix lengths are 
important in the hits.

> On metrics / costs, pick the term you like. I am assuming nothing, I use the
> term metric where others use cost (or mixed usage, as below in the diagrams
> / text). Sample below uses metric where I would use hopcount. 
> 
> I just play a bit with some protocols on some platforms. Here a (part off a)
> routing table snapshot from one of the toys (OLSRv1 adjusted with ETX and
> Link Costs):
> 
>                OLSR Routes in Kernel

Is this the kernel routing table?  Or OLSR's routing table?  I believe 
it's OLSR, not vanilla kernel, because there are two fields 'Metric' and 
'Cost' whereas the vanilla kernel only has 'Metric'.

> Destination		Gateway	 Metric	Cost		Interface
> 10.128.12.0/24	169.254.1.12	1	725.000	ath0
> 10.128.13.0/24	169.254.1.13	1	630.303	ath0
> 10.128.14.0/24	169.254.1.14	1	622.727	ath0
> 10.128.15.0/24	169.254.1.15	1	671.429	ath0
> 10.128.16.0/24	169.254.1.16	1	973.594	ath0
> 10.128.17.0/24	169.254.1.17	1	749.285	ath0
> 10.128.18.0/24	169.254.1.18	1	766.667	ath0
> 10.128.19.0/24	169.254.1.19	1	663.244	ath0
> 10.128.20.0/24	169.254.1.20	1	958.831	ath0
> 10.128.21.0/24	169.254.1.16	2	1853.594	ath0
> 10.128.22.0/24	169.254.1.16	2	1754.594	ath0
> 10.128.23.0/24	169.254.1.16	2	1836.594	ath0
> 10.128.24.0/24	169.254.1.16	2	1662.594	ath0
> 10.128.25.0/24	169.254.1.16	2	1939.594	ath0
> 10.128.26.0/24	169.254.1.26	1	637.633	ath0
> 10.128.27.0/24	169.254.1.27	1	629.622	ath0
> 10.128.28.0/24	169.254.1.28	1	710.918	ath0
> 10.128.29.0/24	169.254.1.29	1	737.511	ath0
> 10.128.30.0/24	169.254.1.30	1	817.725	ath0

For my clarification: this table doesn't contain host-based routes, we 
agree.

Also: are all the addresses 169.254.1.12-30 neighbors of the ath0 
interface?  What is/are the addresses assigned on ath0 of this node?

What is the subnet address of the subnet on which ath0 is connected?

If we have that then I could picture the topoology you're using, and 
draw subnet addresses and routing tables.

> Metrics and cost do not have a need to be "published" in the kernel RT.
> 
> On this toy, LL are multihop reachable (bad behavior !!):
> 
> 169.254.1.21	169.254.1.16	2	1853.594	ath0
> 169.254.1.22	169.254.1.16	2	1754.594	ath0

Right! (LL addresses should be neighbors, not Metric 2.)

Thanks for the routing table dump.

Alex

> 
> Teco.
> 
> 
> 
> |-----Oorspronkelijk bericht-----
> |Van: Alexandru Petrescu [mailto:alexandru.petrescu@gmail.com]
> |Verzonden: dinsdag 3 maart 2009 23:40
> |Aan: Teco Boot
> |CC: autoconf@ietf.org
> |Onderwerp: Re: Autoconf addressing model
> |
> |Teco, I'm happy you updated the obstacles scenario.  That's important
> |insight on what movement may actually be.
> |
> |I'd go further include default routes in the tables, and specific
> |addresses like 10.1.1.1/32 instead of A, and subnet prefixes 10.1.1.0/24
> |for example.
> |
> |Sorry just asking about this: the Cost in the routing tables.  The
> |kernel routing tables don't have variable Cost, they're all metric 1 I
> |believe (all next-hops are 1-hop away).  The routing protocols' tables
> |may have Cost and other variables.
> |
> |Did you assume a routing protocol?
> |
> |My preference is to not assume any routing protocol.
> |
> |Alex
> |
> |Teco Boot a écrit :
> |> Hi Alex,
> |>
> |> I included wrong routing table info in the "obstacles" scenarios.
> |> Here a full set of diagrams with routing table info.
> |>
> |> I removed "STA-", now the model applies to non-802.11 topologies as
> |well.
> |>
> |> Teco.
> |>
> |>
> |>
> |>
> |> 1.  MANET topology with moving and blocking obstacle
> |>
> |>           +------------------------+   +------------------------+
> |>           |                        |   |                        |
> |>           |           ______B      |   |           ______B      |
> |>           |       ___/      |      |   |       ___/             |
> |>           |      A          |      |   |      A       OBSTACLE  |
> |>           |      '--_       |      |   |      '--_              |
> |>           |          '------C      |   |          '------C      |
> |>           |  OBSTACLE              |   |                        |
> |>           +------------------------+   +------------------------+
> |>               1-1: Full connected          1-2: B-C via A
> |>
> |>           +------------------------+   +------------------------+
> |>           |                        |   |          O             |
> |>           |           ______B      |   |          B      B      |
> |>           |       ___/      |      |   |          S      |      |
> |>           |      A      OB  |      |   |      A   T      |      |
> |>           |            ST   |      |   |          A      |      |
> |>           |           AC    C      |   |          C      C      |
> |>           |         LE             |   |          L             |
> |>           |                        |   |          E             |
> |>           +------------------------+   +------------------------+
> |>                1-3: A-C via B          1-4: A-B and A-C blocked
> |>
> |>
> |>    The routing tables for the MANET Routers look as follows:
> |>
> |>         ROUTER   DEST   NEXTHOP COST    ROUTER   DEST   NEXTHOP COST
> |>        +-------+-------+-------+----+  +-------+-------+-------+----+
> |>        |   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   |   A   |  2 |
> |>        +-------+-------+-------+----+  +-------+-------+-------+----+
> |>        |   C   |   A   |   A   |  1 |  |   C   |   A   |   A   |  1 |
> |>        |       |   B   |   B   |  1 |  |       |   B   |   B   |  2 |
> |>        +-------+-------+-------+----+  +-------+-------+-------+----+
> |>              1-1: All single hop             1-2: B-C degraded
> |>
> |>        +-------+-------+-------+----+  +-------+-------+-------+----+
> |>        |   A   |   B   |   B   |  1 |  |   A   |       |       |    |
> |>        |       |   C   |   B   |  2 |  |       |       |       |    |
> |>        +-------+-------+-------+----+  +-------+-------+-------+----+
> |>        |   B   |   A   |   A   |  1 |  |   B   |       |       |    |
> |>        |       |   C   |   C   |  1 |  |       |   C   |   C   |  1 |
> |>        +-------+-------+-------+----+  +-------+-------+-------+----+
> |>        |   C   |   A   |   B   |  2 |  |   C   |       |       |    |
> |>        |       |   B   |   B   |  1 |  |       |   B   |   B   |  1 |
> |>        +-------+-------+-------+----+  +-------+-------+-------+----+
> |>               1-3: A-C degraded           1-4: A-B and A-C blocked
> |>
> |>
> |>
> |> 2.  MANET topology with moving and degrading obstacle
> |>
> |>     In these scenarios, link metrics are introduced.
> |>
> |>           +------------------------+   +------------------------+
> |>           |                        |   |                        |
> |>           |          _______B      |   |           ______B      |
> |>           |       __/ 1     |      |   |       __/ 1     .      |
> |>           |      A          | 1    |   |      A        obstacle |
> |>           |      '--_ 1     |      |   |      '--_ 1     . 5    |
> |>           |          '------C      |   |          '------C      |
> |>           |  obstacle              |   |                        |
> |>           +------------------------+   +------------------------+
> |>                2-1: No hindrance            2-2: B-C degraded
> |>
> |>           +------------------------+   +------------------------+
> |>           |                        |   |          o             |
> |>           |           ______B      |   |       5  b .....B      |
> |>           |       ___/ 1    |      |   |       ...s.     |      |
> |>           |      A      ob  | 1    |   |      A   t      | 1    |
> |>           |       ...  st   |      |   |       ...a.     |      |
> |>           |       5  .ac.... C     |   |       5  c .....C      |
> |>           |         le             |   |          l             |
> |>           |                        |   |          e             |
> |>           +------------------------+   +------------------------+
> |>              2-3: A-C degraded          2-4: A-B and A-C degraded
> |>
> |>
> |>    The routing tables:
> |>
> |>         ROUTER   DEST   NEXTHOP COST    ROUTER   DEST   NEXTHOP COST
> |>        +-------+-------+-------+----+  +-------+-------+-------+----+
> |>        |   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   |   A   |  2 |
> |>        +-------+-------+-------+----+  +-------+-------+-------+----+
> |>        |   C   |   A   |   A   |  1 |  |   C   |   A   |   A   |  1 |
> |>        |       |   B   |   B   |  1 |  |       |   B   |   A   |  2 |
> |>        +-------+-------+-------+----+  +-------+-------+-------+----+
> |>               2-1: No hindrance               2-2: B-C degraded
> |>
> |>        +-------+-------+-------+----+  +-------+-------+-------+----+
> |>        |   A   |   B   |   B   |  1 |  |   A   |   B   |   B   |  5 |
> |>        |       |   C   |   B   |  2 |  |       |   C   |   C   |  5 |
> |>        +-------+-------+-------+----+  +-------+-------+-------+----+
> |>        |   B   |   A   |   A   |  1 |  |   B   |   A   |   A   |  5 |
> |>        |       |   C   |   C   |  1 |  |       |   C   |   C   |  1 |
> |>        +-------+-------+-------+----+  +-------+-------+-------+----+
> |>        |   C   |   A   |   B   |  2 |  |   C   |   A   |   A   |  5 |
> |>        |       |   B   |   B   |  1 |  |       |   B   |   B   |  1 |
> |>        +-------+-------+-------+----+  +-------+-------+-------+----+
> |>              2-3: A-C degraded          2-4: A-B and A-C degraded
> |>
> |>    In this scenario, the most optimal paths are used, a 2-hop path
> |with
> |>    metric 2 is used instead of a single hop path with metric 5.
> |>
> |>
> |>
> |> 3.  MANET topology with degrading obstacle and noise
> |>
> |>     In this scenario, C can hear A through an obstacle as scenario 2-
> |3,
> |>     but A reception of B and C is affected by high level "NOISE" (3.1)
> |>     or low level "noise" (3-2). With high level noise, A cannot hear C
> |and
> |>     the link is "uni-directional".
> |>
> |>     Term "asymmetric" is used to indicate unbalanced metrics for the
> |> direction
> |>     of traffic between two nodes. In other documents, "asymmetric" is
> |used
> |> for
> |>     what is called "uni-directional" here.
> |>
> |>
> |>           +------------------------+   +------------------------+
> |>           |                        |   |                        |
> |>           |           ____1_B      |   |           ____1_B      |
> |>           |       3__/      |      |   |       2__/      |      |
> |>           |      A       ob | 1    |   |      A      ob  | 1    |
> |>           | NOISE      st   |      |   | noise ...  st   |      |
> |>           |         x.ac.>..C      |   |      10  .ac....C      |
> |>           |         le             |   |         le     5       |
> |>           +------------------------+   +------------------------+
> |>            3-1: A-C uni-directional     3-2: A-C & B-C asymmetric
> |>                 A-B asymmetric
> |>
> |>
> |>       ROUTER   DEST   NEXTHOP METRIC    ROUTER   DEST   NEXTHOP METRIC
> |>      +-------+-------+-------+------+  +-------+-------+-------+------
> |+
> |>      |   A   |   B   |   B   |    3 |  |   A   |   B   |   B   |    2
> ||
> |>      |       |   C   |   B   |    4 |  |       |   C   |   B   |    3
> ||
> |>      +-------+-------+-------+------+  +-------+-------+-------+------
> |+
> |>      |   B   |   A   |   A   |    1 |  |   B   |   A   |   A   |    1
> ||
> |>      |       |   C   |   C   |    1 |  |       |   C   |   C   |    1
> ||
> |>      +-------+-------+-------+------+  +-------+-------+-------+------
> |+
> |>      |   C   |   A   |   B   |    2 |  |   C   |   A   |   B   |    2
> ||
> |>      |       |   B   |   B   |    1 |  |       |   B   |   B   |    1
> ||
> |>      +-------+-------+-------+------+  +-------+-------+-------+------
> |+
> |>            3-1: A-C uni-directional     3-2: A-C & B-C asymmetric
> |>                 A-B asymmetric
> |>
> |>    When the noise level near station A is intermitting between high
> |and low
> |>    levels, this does not influence the routing topology, as the MANET
> |> protocol
> |>    has selected path A-B-C between the routers A and C, because better
> |> metrics
> |>    and bidirectional validation.
> |>    The MANET Routing Protocol checks directionality of links before
> |using
> |> these.
> |>
> |>
> |>
> |>
> |>
> 
>