Netdisco / Netdisco 2 / #114 Handling neighbors with multiple CDP/LLDP entries

Oliver Gorwits - 2014-04-30

Ticket moved from /p/netdisco/netdisco2/113/

If you would like to refer to this comment somewhere else in this project, copy and paste the following link:

Oliver Gorwits - 2014-04-30

Ticket moved from /p/snmp-info/bugs/55/

Can't be converted:

_milestone: None

_priority: None
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:

The following patch handles the multiple LLDP/CDP entries, and also:

keeps available information, by concatenating entries
minimizes string length, by removing duplicates
avoids randomly ordering changes, by sorting entries
maximizes port matches, by prioritizing known port names

bash> cd .../perl5/lib/perl5/App/Netdisco/Core
bash> diff Discover.pm.original.v2.027004 Discover.pm.patched
687c687,688
<               $remote_type = 'AP: '. $remote_type;
---
>               $remote_type = 'AP: '. $remote_type
>                 if $remote_type !~ /\bAP\b/; # avoid unnecessarily making LLDP differ from CDP
690c691,692
<           $portrow->update({remote_type => $remote_type});
---
>           # save remote_type immediately, only if no previous value, else save later
>           $portrow->update({remote_type => $remote_type}) unless ($portrow->remote_type);
783a786,820
>       # handle multiple records for same neighbor (eg: due to CDP and LLDP, or multiple CDP)
>       if ((defined $portrow->remote_ip) and ($portrow->remote_ip eq $remote_ip)) {
>         debug sprintf
>           ' [%s] neigh - port %s has more %s info: port (%s) & (%s), id (%s) & (%s), type (%s) & (%s)',
>           $device->ip, $port, $portrow->remote_ip,
>           $portrow->remote_port, $remote_port,
>           $portrow->remote_id  , $remote_id,
>           $portrow->remote_type, $remote_type;
>
>         # for remote_id and remote_type, concatenate new info with existing, de-duplicate and sort
>         $remote_id  =join(' | ',sort(keys{map{$_, 1}(split(/ \| /,$portrow->remote_id  ),$remote_id  )}));
>         $remote_type=join(' | ',sort(keys{map{$_, 1}(split(/ \| /,$portrow->remote_type),$remote_type)}));
>
>         # for remote_port, try to find a valid (known) port
>         my $old=$portrow->remote_port;
>         my $new=$remote_port;
>         if ( $old && $new && ($old ne $new) &&
>              (index($old, " | ") == -1) &&
>              (schema('netdisco')->resultset('DevicePort')
>                  ->single({ip => $remote_ip, port => $old})) ) {
>             $remote_port = $old; #already had valid port; keep it and throw away new info
>         }
>         elsif ( $old && $new && ($old ne $new) &&
>                 (index("| $old |", "| $new |") == -1) &&
>                 (schema('netdisco')->resultset('DevicePort')
>                    ->single({ip => $remote_ip, port => $new})) ) {
>             $remote_port = $new; #new port is valid; keep it and throw away old info
>         }
>         else {
>           # neither is a valid port; concatenate new info with existing, de-duplicate and sort
>           $remote_port=join(' | ',sort(keys{map{$_, 1}(split(/ \| /,$portrow->remote_port),$remote_port)}));
>         }
>
>      }
>

Oliver Gorwits - 2014-07-29

Hi Joel,

Unfortunately your patch does not cleanly apply to my copy of the source tree (even with offsets, there is an error in the third hunk).

Please would you be able to send the output of diff -urN as an attachment?

regards,
oliver.

If you would like to refer to this comment somewhere else in this project, copy and paste the following link:

Oliver Gorwits - 2014-07-29

status: new --> taken

assigned_to: Oliver Gorwits
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:

Joel Leonhardt - 2014-07-29

Hi Oliver,

Here is an updated diff, with the patch applied to App-Netdisco-2.028012.

Attachment: diff-urN_v2.028012.txt

diff-urN_v2.028012.txt

If you would like to refer to this comment somewhere else in this project, copy and paste the following link:

Oliver Gorwits - 2014-07-31

Many thanks Joel,

We discussed this in the dev team and we'll probably apply parts of the patch at first, and consider the implications of other parts separately. The sorting is a good idea, as is checking the port on the remote device. The concatenation of IDs needs more discussion.

Thanks once again,

If you would like to refer to this comment somewhere else in this project, copy and paste the following link:

Oliver Gorwits - 2014-07-31

Hi, in the end I've taken a different tack, and I'd appreciate you letting us know whether it makes a difference.

I've applied a sort to the processing of neighbor data, so that should make it at least consistent. I've added a version of your patch to match APs with "AP" in the remote type.

As mentioned above, I've left the concatenation to one side for now. We need to think a bit more about the implications. In you case it seems actually that the HP is simply making some questionable decisions about how it presents CDP and LLDP data in the SNMP MIB. What would be better is for us to handle receiving legitimate multiple neighbors where there's e.g. an unmanaged switch passing through the data. That would require something a bit smarter in Netdisco and possibly a DB Schema modification.

Please do feed back whether the next release helps with the consistency and AP detection (wifi icon should appear in ports view), at least.

regards,
oliver.

If you would like to refer to this comment somewhere else in this project, copy and paste the following link:

Oliver Gorwits - 2014-07-31

status: taken --> closed
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:

Handling neighbors with multiple CDP/LLDP entries

Full-featured enterprise network management tool

Searches

Help

#114 Handling neighbors with multiple CDP/LLDP entries

Discussion