Vinod Arya Tue, 01/28/2014 - 22:19
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Ciscoworks can use various mechanisms to discover the devices on your network.


The network administrator can discover the devices using different protocols, such as Cisco Discovery Protocol, BGP, OSPF, Address Resolution Protocol (ARP), HSRP, cluster, routing table, and ping sweep on IP range, that are activated at different layers of the Open Systems Interconnection (OSI) model in the device.


It has a benefit when the devices on the network will not be better responsive to any other modules of Discovery.


Usually other module learn IP of the neigbour device with their data, like asking CDP neighbour details or OSPF Table. Whereas in Ping Sweep LMS will simply continue to check devices based on the IP Range.


Example, if you selected Ping Sweep On IP Range, you can specify the seed device as 10.77.209.209 and the subnet mask as 255.255.255.240. Entering a smaller subnet mask value may result in a longer discovery cycle, as discovery has to sweep IP addresses from more networks. It is recommended to enter a Class C mask instead of a Class A or B mask.


So using Ping Sweep helps you find your devices faster of it is failry simple network with simple range of IP's on devices, may be on a single subnet.


More details on How Ping Sweep Algorithm Works technically behind, in LMS, is available here:

https://supportforums.cisco.com/docs/DOC-9005#Ping_Sweep_On_IP_Range


This document describes, in depth about all modules used in LMS Device Discovery.


Hope it will be helpful to understand.


-Thanks

Vinod

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raquel_mh Wed, 01/29/2014 - 07:04
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Hi Vinod Arya,



I want to know .if I use the ping sweeps .I generate broadcast in the network and that  would be a problem.


thanks for the reply.

Vinod Arya Wed, 01/29/2014 - 09:11
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Ideally that is something to be decided by the Network Administrator.


Ping Sweep will have a burst of ICMP requests on each IP on the Range or Subnet.


If the network is small, it will be fairly small ping request. But say if there is a big network there will be ICMP traffic, but usually we have never seen any Impact due to this.


For example, say you have multiple class C (or smaller) subnets carved out of the class B 172.16.0.0/16.  DCR can only handle 50,000 devices, and the largest single LMS installation can support 10,000.  A full class B can have over 65,000 hosts. 


This way you can calculate the amount of Traffic LMS will generate. I would say it should not be impacting, though it on you to analyze and decide as per the network.


-Thanks

Vinod

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