I still don't understand the consequences of the Discovery Options 'Use DCR as Seed List' and 'Hop Count'
How does they work in detail?
Cisco says in LMS 2.6 and below all devices in DCR where used as a starting point for any Discovery Cycle after the first initial Discovery. Only for the first initial Discovery the Seed Device List (manual added or import from a file) was used to populate devices into DCR. After that any device from DCR was used for discovery of additional devices. Restriction for discovery could be done only by Discovery Filters and the option 'Jump Router boundaries';
But the discovery process changed in LMS3.x ...
Does CSDiscovery now only use Devices in DCR as seed devices if this option is enabled? If yes, which purpose does it have? Will it cause all Devicves in DCR to be populated in to the list of seed devices? Will it speed-up the disco process?
On the other hand, if this option is not enabled which consequences does it have? Will only the devices listed as seed devices in 'Seed Device Settings' (Global or Module settings) be used? - could this slow down discovery?
The same is with HOP count: how will CSDiscovery behave if there is e.g.a HOP count of 3?
If I look at the 'LMS Workflow Demos' from LMS 3.1 it says 'Router Hops'- another person told me it is the diameter - which I understand as a 'device hop' (regardless of device type) and which could be a significant difference.
Together with the option 'use DCR as seed list' it seems to be useless ...or hard to understand (at least for me...)
Think of the following simple situation:
10 devices in a row (dev1 - dev10), CDP is enabled;
CSDiscovery has the following config:
discovery module: CDP
seed device: dev1; hop count:3
use DCR as Seed List: yes
no Filters
Now I have different options how disco could work:
Option 1:
the first disco cycle should find exactly 3 devices (dev1 - dev3)
the second disco cycle should start with dev1, dev2, dev3 as seeds and finds dev4 - dev6 as new devices
the third disco cycle should start with dev1-dev6 and finds dev7-dev9
and so on..
(which means the hop count applies to all devices found and added to DCR but in fact does not really restrict discovery but instead interferes with it)
Option 2:
the first disco cycle should find exactly 3 devices (dev1 - dev3)
the second disco cycle should start with dev1-dev3 and finds dev4 -dev10
(which means the hop count applies only to dev1, but because of 'Use DCR as Seed List' there is no Hop count definied for dev2 and dev3 - which means it is not restricted- so it finds all devices)
Option 3:
the first disco cycle should find exactly 3 devices (dev1 - dev3)
the second disco cycle will not find any new device
no subsequent disco cycle will find a new device
(which means Disco will start with dev1-dev3 find at least dev4-dev6 but drops all because the Hop count of dev1 restrict the addition to DCR - for any device included and behind dev4 )
Option 4:
the first disco cyle finds all devices
(which mean for dev1 it is restricted to 3 hops, but not for dev2 and dev3 and thus it finds all)
(or it is a router hop count and because of dev1-dev10 beeing in the same IP segment it does not have any effect..)
or is it completely different?
depending on how it really works I could think of some (great?) performance degredation caused by the ongoing and perhaps useless calculation of the Hop count...
As well 'Use DCR as Seed List' could have an impact on the number of parallel threads CSDiscovery uses.
ANY CLARIFICATION AND COMMENT ON THIS IS GREATLY APPRECIATED!
