[hobbit] Dependency sytem in Hobbit

[Hubbard, Greg L]

Etienne -- you are going to have to find someone to write that and add
it to Hobbit.  Path-based alarm suppression is one of the holy grails in
the network management industry, and the reason it has not yet been
solved is because it is a difficult problem.  For small networks you can
come up with a solution, but if you are using VLANs and WAN's and load
balancers and all that other stuff it gets to be rather difficult.
 
There are many commercial software vendors that claim to have this
problem solved -- but sometimes even their demos do not work.  The
little bit of dependency specification that you can put into Hobbit does
indeed work, but not across the board.
 
GLH


________________________________

	From: Marganne, Etienne [mailto:emarganne at be.tiauto.com] 
	Sent: Friday, January 19, 2007 5:58 AM
	To: hobbit at hswn.dk
	Cc: henrik at hswn.dk
	Subject: [hobbit] Dependency sytem in Hobbit
	
	

	Hello all,

	 

	I am Etienne Marganne, a new comer in TI Automotive, a society
which uses Hobbit as a monitoring tool, I will be in charge of Hobbit
tool. We would like to enhance our monitoring tool in order to get more
detailed informations through it.

	 

	One of the first thing we would like to do is to create a
dependency system between monitored hosts across our network. For all
the further discussion, please keep in mind that we have a very large
network and two Hobbit servers where we would like to keep the same
"hh-hosts" file. 

	The idea of the dependency system is the following one: once we
have a host that fails on a network path in our network all the hosts
further that one will be very likely unreachable. This will cause a lot
of alerts to be triggered because of one failure. This is not
interesting because our team will be flooded by those alerts. Therefore
it could be useful to create dependencies so that those further devices
on the same path will not trigger alerts (basically turning red).

	There is a specific tag that can be used to do such a work, the
"route" tag. In our case with two Hobbit servers, we would tune that
with the "route_BBLOCATION" tag. Knowing that there are Hobbit clients
on all the network nodes between the two endpoints, the simplest idea
would be to list all the nodes in the description of those tags. This
could work even if it would generate of job. A little bit further here,
let's say that one node fails on a path, it is very probable that if you
know that the following nodes are unreachable, you may not want to test
them anymore (to forbid them to turn red). 

	 

	Now think of a big network with a lot of redundancy, it is very
probable that there will be indeed a lot of network paths between a
server and one final host. If on one path one node fails, it does not
mean that the final client is not reachable. But with the "route" tag,
that client would be signal as unreachable since a member of the "route"
has failed. This is not comfortable at all. 

	 

	What we would like to know, or to get, if there is a way to get
this dependency system work: 

	 

	Hobbit Server A ---- 1 ---- 2 ---- 3 ---- 4 ---- Final Client

	                  |                                         |

	                  | --------- 5 ------------6 ----------- | 

	 

	There are two paths to reach the Final Client, one composed by
1, 2, 3, 4 and another one composed by 5, 6. 

	With the current "route" tag we would have such a list of nodes:
route_HobbitServerA:1,2,3,4,5,6 then if 1 fails and the path 1-2-3-4
would not work anymore but the 5-6 one would still. 

	 

	A good dependency system would to have such a thing: Final
Client depends on 4, 4 depends on 3, 3 depends on 2, 2 depends on 1 but
Final Clients also depends on 6 which depends on 5. More over this would
also solve that kind of topology :

	Hobbit Server A ---- 1 ---- 2 ---- 3 ---- 4 ---- Final Client

	                  |                    |                    |

	                  | --------- 5 ------------6 ----------- |
Where there is a link between 2 and 5, 2 and 6, 5 and 3, 6 and 3.

	 

	Maybe that something could be set up with the "depends" tag,
however I do not know how the informations will propagate through the
different dependencies done that tag.

	 

	 

	Even further on the topic, the "route" tag performs only ping
tests which does not seem enough to me. I would like to add cpu, disks,
... tests to the whole dependency system.

	 

	 

	Thank you for your help and answers,

	 

	Regards,

	 

	Etienne Marganne

	TI Automotive.

	 

	 

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