[Sis-csi] Re: Emergency Commanding (was IP Header Compression)

[Wesley Eddy]

On Fri, Sep 09, 2005 at 09:47:37AM -0400, Scott,Keith L. wrote:
> 
> Choosing IPIDs as the magic bits is (IMHO) particularly problematic
> because:
>   o They are (supposed to be) monotonically increasing and hence WILL
> hit the magic pattern, it's just a matter of time.

There's no requirement that they be monotonically increasing or behave in
any specific way (grep RFC 791).  That's merely a cheap way to implement
uniqueness of IDs for an MSL.

>   o If you restrict to a particular set of source addresses and go
> messing with the networking stacks of these 'special' boxes to preclude
> certain IPIDs, you've sort of blown the model of using COTS software.
> May as well pay the extra 8 bytes at this point and go to UDP src/dst
> ports.

That makes sense to me, as long as the port numbers used are low numbered
and already assigned to some type of application that's been long dead and
has no hope of being revived.

-Wes 

-- 
Wesley M. Eddy
Verizon FNS / NASA GRC
http://roland.grc.nasa.gov/~weddy
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