RE: [Manet-dt] DYMO Routing Information Freshness Check

["Koojana Kuladinithi" <[e-mail]>]

Hi Ian

Statement 1 abt Stale is wrong. Isn't it "Node.SeqNum - Route.SeqNum" <
0 ??

Staement 2 abt Loop prone -> "If Node.HopCnt > Route.HopCnt + 1, then
the routing information is loop-prone" should valid only for invalid
routes????


Kind regards

Koojana
 

> -----Original Message-----
> From: Ian Chakeres [mailto:[e-mail]] 
> Sent: 24 June 2006 19:01
> To: [e-mail]
> Subject: [Manet-dt] DYMO Routing Information Freshness Check
> 
> 
> In DYMO when a RREQ/RREP is received a node needs to check 
> whether the information is fresh. In the soon to be released 
> new version I have revised the description of the process 
> (and categories) for routing information freshness.
> 
> I would like you comments before submitting the ID. Please 
> let me know if you suggest any changes.
> 
> Thanks.
> Ian
> 
> 5.2.1.  Judging New Routing Information's Usefulness
> 
>    Given a routing table entry (Route.SeqNum, Route.HopCnt, and
>    Route.ValidTimeout) and new routing information for a 
> particular node
>    in a RM (Node.SeqNum, Node.HopCnt, and RM message type - 
> RREQ/RREP),
>    the quality of the new routing information is evaluated to 
> determine
>    its usefulness.  The following comparisons are performed in order:
> 
>    1. Stale
>       If Node.SeqNum - Route.SeqNum > 0 (using signed 16-bit 
> arithmetic)
>       the information is stale.  Using stale routing 
> information is not
>       allowed, since doing so might result in routing loops.
> 
>    2. Loop-prone
>       If Node.SeqNum = Route.SeqNum the information maybe loop-prone,
>       additional information must be examined.  If Route.HopCnt is
>       unknown or set to zero (0), then the routing 
> information is loop-
>       prone.  Likewise, if Node.HopCnt is unknown or set to zero (0),
>       then the routing information is loop-prone.  If Node.HopCnt >
>       Route.HopCnt + 1, then the routing information is loop-prone.
>       Using loop-prone routing information is not allowed, since doing
>       so might result in routing loops.
> 
>    3. Inferior
>       If Node.SeqNum == Route.SeqNum the information may be inferior,
>       additional information must be examined.  If the route is valid
>       (by examining Route.ValidTimeout and the current time), then the
>       new information is inferior if Node.HopCnt > Route.HopCnt.
>       Additionally, if the route is valid, then the new information is
>       inferior if Node.HopCnt == Route.HopCnt and the Message 
> containing
>       the new information is a RREQ.
> 
>    4. Fresh
>       Routing information that does not match any of the 
> above criteria
>       is loop-free and better than the information existing in the
>       routing table.  This information should be used to update the
>       routing table.
> 
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> 


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