Subject: [6lowpan] comments on the load document

From: "Kushalnagar, Nandakishore" <[email-masked]>
Date: Wed, 3 Aug 2005 16:49:51 -0700

Daniel,
 
I think it seems to be a pretty comprehensive document to tailor AODV
for 6lowpan.
 
I have 1 major comment and 1 suggestion.
The accumulation routing metric tbd in this document is interesting as I
see the reason you want to do this is to give a holistic picture of
bidirectional routing. 
 
But just accumulation of the routing cost as is has these problems:
1. the route reply cost will always be worser than the request cost and
hence the underlying operation would change for route comparison with
forward and reverse metrics. (section 
2. as far as I see this is an option that vendors MAY choose to
implement and hence must be an option. 
 
I would like to propose an idea of having routing metric type:
If we think of sensor networks, the path chosen depends on what kind of
metric you choose. In 6lowpans, these metrics can be dynamic. For
example imagine when all nodes are running on full power, the nodes may
choose routing metric to be end to end delay, lqi, hop count, etc. When
nodes start loosing battery, the nodes may want to choose a different
metric based on remaining life time. Thus a routing metric type within
the routing header is extremely important to lowpans more than other
kinds of network. Here we can say how we plan to accomplish this within
the LOAD scope as there are a lot of bits available to use.
 
Here is my suggestion:
The current format for route request is:
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Type      |R|D|O|Reserved |   RREQ ID     |   Route cost  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 Link Layer Destination Address                /
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 Link Layer Originator Address                 /
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 <Fig. 1. RREQ message format>
 
Suggested format change for route request could be:
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Type  |R|D|O|B| Cost Type     |   RREQ ID     |   Route cost  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 Link Layer Destination Address                /
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 Link Layer Originator Address                 /
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                 <Fig. 1. RREQ message format>
 
      B: Bidirectional cost when accumulation happens in a bidirectional
manner
      Cost Type: This is a cost type that dictates the type of routing
cost present in the header.
                 The following are the current cost types known:
                 0: Hop count(All routing implementations must support
this type)
                 1: End to end delay
                 2: lqi
                 3: Battery lifetime

                 4-127: TBD
                 128-255: Vendor dependent
 
The current format for route response is:
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Type      |R|D|O|Reserved |   RREQ ID     |   Route cost  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                Link layer Destination Address                 /
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                Link layer Originator Address                  /
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                    <Fig. 2. RREP message format>
 
Suggested format change is:
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Type  |R|D|O|B| Cost Type     |   RREQ ID     |   Route cost  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                Link layer Destination Address                 /
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                Link layer Originator Address                  /
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                    <Fig. 2. RREP message format>
 
      B: Bidirectional cost when accumulation happens in a bidirectional
manner
      Cost Type: This is a cost type that dictates the type of routing
cost present in the header.
                 The following are the current cost types known:
                 0: Hop count (All routing implementations must support
this type)
                 1: End to end delay
                 2: lqi
                 3: Battery lifetime

                 4-127: TBD
                 128-255: Vendor dependent
 
Current RERR message error codes
        Numeric value for describing error.
                   0x00 = No available route
                   0x01 = Low battery
                   0x02 - 0xff = reserved (TBD)
 
Suggested changes in error codes:
                   0x00 = No available route
                   0x01 = routing cost not supported
                   0x02 - 0xff = reserved (TBD)

Nandu
 
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