Re: [tkined] Subnet-zero and one another

Peter Polkinghorne (Peter.Polkinghorne@brunel.ac.uk)
Mon, 14 Dec 1998 15:16:18 +0100

>
> >
> > This is a good question and has sometimes bothered me in the past. What is needed is a standard for how to represent netmasks and some routines to manipulate - input, output, membership of nework and all members of a network - should be enough?
>
> This much work is not necessary. The relationship between network
> numbers and netmasks is pretty straight-forward and the network
> membership falls out when you apply the mask to the network number. Its
> a bit-wise comparison but I don't remember if it is an & or an | and
> which numbers have to be worked on. Give me some time to play with this
> and I'll get back to you if you wish.
>
Well there are at least 2 common representations of netmasks (with sometimes
optional hex representations:

134.83.112.0/8

or

134.83.112.0/255.255.255.0

and you will find manipulating them in Tcl is non trivial - but obviously not
impossible. Hence suggesting some support ...

> If subnet mask was added to the IP discover, then only the devices on
> that network would be polled for ip discover. This would cut down on a
> lot of the bandwidth the current implementation uses. I have found that
> SNMP IP discover routines from other managers (which also don't use
> subnet mask to limit their search) can flood a network and bring it to
> its knees. I expect tkined will have similar results which is why I
> hesitate to use it esp. when I have a subnet with a mask of
> 255.255.255.0 and tkined is searching a network with a mask of 255.0.0.0
> because it is using classful masks. That's a lot of wasteful traffic!!!
>
This I agree with ...

> - Matthew
>
> --
> ---
> ------
> Matthew Levine
> Quality Assurance (Global Alliances)
> Cisco Systems, Santa Cruz http://www.cisco.com/
> mlevine@cisco.com (408) 457 - 5431

-- 
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| Peter Polkinghorne, Computer Centre, Brunel University, Uxbridge, UB8 3PH,|
| Peter.Polkinghorne@brunel.ac.uk   +44 1895 274000 x2561       UK          |
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