Re: [tkined] Subnet-zero and one another

Matthew Levine (mlevine@cisco.com)
Fri, 11 Dec 1998 17:34:09 -0800

>
> 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.

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!!!

- Matthew

>
> This information is gathered by ip_discover, but then thrown away - as is the detail of all the other addresses that a node might have. But I would be reluctant to add this extra info if this would break existing tools or they could not take advantage of it.
>
> I suppose one could have extra attributes like netmask and address list?
>
> Any views on this - Juergen?
>
> --
> -----------------------------------------------------------------------------
> | Peter Polkinghorne, Computer Centre, Brunel University, Uxbridge, UB8 3PH,|
> | Peter.Polkinghorne@brunel.ac.uk +44 1895 274000 x2561 UK |
> -----------------------------------------------------------------------------
>
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-- 

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

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