Re: [Netdisco] alias hack

[Nenad T. <Nen...@bn...>]

Hi,

>Hi Nenad,

>> As I have already mentioned in my earlier messages, the only
>> problematic thing with Netdisco for me is aliasing which doesnt
>> discover neighbours if they have same IP address and I have several
>> devices in different routing domains which have same private address
>> on them.    

>OK, so each device has a unique "root ip" and refresh + arpnip work correct? Is it just that a specific set of IP addresses / subnets has to be kept out >of the device_ip (aliases) table?

Everything works ok, but if I have two devices with 192.168.0.1/24 on LAN side (and I have many of those either on LAN sides either in VRF's), the first one that is discovered will be neighbour with every device that "see" some other device with same IP on it.
I have already tryed with dont discover network/interfaces in netdisco.conf but thats not good because I have some private ranges which are used on customers LAN side and we use them as management IP's for other equipment.  
 

> Or maybe someone has better idea?

>>Well, if this works for you, we could perhaps add a config option to ignore certain networks when storing device IPs. However I'm not sure whether your >>approach will work... let's wait for the results first.

I have already tested script and its dirty but it works. The only problem is I must execute script in really short intervals to be sure there will be no duplicate IP's in alias column and that doesnt look good to me and I cant search devices by those aliases because there are not in database. 

>>In the long run, we'll have to find a way to support duplicate IP addresses on devices for stuff like VRFs and anycast addresses. I'm not sure how we >>can implement that in a reliable way though.

I have been thinking about that for a long time and I think there is two reliable ways, one is to compare hostport/CPU mac addresses or, probably simpler, serial numbers.

So that could be something like;

If neighbour seems to be alias of already discovered device and serial number of neighbour = device which have that IP in alias column and serial number of that dvice
Then dont discover that neighbour 
Else
Discover it and put a static connection mapping in database

Unfortunately, that seems like a lot of work and my programming skills are not even near to be able to do something like that. 
I suppose it could also have impact on overall performance of network discovery (you must poll serial number before anything else and on every device) so maybe it will be good to make that or something similar optional.

Well, for me will be ok and possibility to exclude some IP's from writing in alias column but thats also not optimal, maybe in some moment I will want to find all those aliases.. But its better then delete those entrys every few minutes..

Anyway, if somebody do something in that direction, I'm ready to be guinea pig for testing as long as it takes, thats the only thing which lacks from declaring Netdisco absolutely perfect. :)

>Regards,

>Jeroen van Ingen
>ICT Service Centre
>University of Twente, P.O.Box 217, 7500 AE Enschede, The Netherlands

Regards,

Nenad