Re: [Netdisco] Topology through linux bridge

[Rodney F. <rfl...@ac...>]

David,
Thanks for the response.  Yes, while on my netdisco box:
netdisco-box:~# snmpget -v1 -c public myservername sysServices.0
SNMPv2-MIB::sysServices.0 = INTEGER: 76

I ran against that some time ago.  I did have an error in my snmpd.conf 
file (no space between "sysServices" and "76")

Shortly after this post, I made another one with seems to be with using 
lldpd and netdisco not recognizing that CDP is enabled with lldpd.

Don't I need lldpd working so netdisco can detect my neighbors?  Please, 
see my later post if you want details.

Thanks a million!


On 10/23/2012 06:41 PM, David Baldwin wrote:
> Jay,
>
> I'm assuming you've checked you can retrieve SNMP info from the Linux
> box from your netdisco server already.
>
> The key with recognising Linux (or Linux based appliances) in my
> experience is the sysServices MIB variable - here's one I set up to
> solve that problem:
>
> $ snmpget linuxhost SNMPv2-MIB::sysServices.0
> SNMPv2-MIB::sysServices.0 = INTEGER: 76
>
> You can define the value of this in snmpd.conf - from the man page:
>
> SYSTEM INFORMATION
>         Most  of  the information reported by the Net-SNMP agent is
> retrieved from the underlying system,
>         or dynamically configured via SNMP SET requests (and retained
> from one run of the  agent  to  the
>         next).   However, certain MIB objects can be configured or
> controlled via the snmpd.conf(5) file.
>
>     System Group
>         Most of the scalar objects in the ’system’ group can be
> configured in this way:
>
>         sysLocation STRING
>
>         sysContact STRING
>
>         sysName STRING
>                set the system location, system contact or system name
> (sysLocation.0,  sysContact.0  and
>                sysName.0)  for  the agent respectively.  Ordinarily these
> objects are writeable via suit-
>                ably authorized SNMP SET requests.  However, specifying
> one of these directives makes  the
>                corresponding  object read-only, and attempts to SET it
> will result in a notWritable error
>                response.
>
>         sysServices NUMBER
>                sets the value of the sysServices.0 object.  For a host
> system, a good value is 72 (appli-
>                cation  +  end-to-end  layers).  If this directive is not
> specified, then no value will be
>                reported for the sysServices.0 object.
>
>         sysDescr STRING
>
>         sysObjectID OID
>                sets the system description or object ID for the agent.
> Although these  MIB  objects  are
>                not  SNMP-writable,  these  directives can be used by a
> network administrator to configure
>                suitable values for them.
>
> You can fake up any of these variables to match an existing device with
> equivalent functionality in netdisco to save having to hack the device
> recognition code in SNMP::Info
>
> David.
>
>> Greetings,
>>
>> I have linux computers with bridged interfaces in my networks.  These
>> machines sit before the routers and act as HTTP proxies.  They have 2
>> nics bridged together.
>>
>> I'm trying to get netdisco to discover my networks, but it never gets
>> past my linux boxes.  Somehow they are stopping the discovery process.
>> I have installed snmpd on these boxes and I can snmpwalk them from the
>> netdisco server.  I believed that installing lldpd would allow netdisco
>> to see these.  I installed lldpd and ran it in foreground with "lldpd -d
>> -c -e -s -x", enabling supporg for CDP, plus starting the agentx (which
>> I believe extends SNMP so I could read network interfaces that are bridged).
>>
>> Still, I get nothing:
>> [xxx.xxx.xxx.xxx]  SNMP::Info::_global(layers) (noSuchName) There is no
>> such variable name in this MIB.! Device Not Supported or I can't connect
>> to it via SNMP.
>>
>> Netdisco will not go through.
>>
>> Lastly, our network consists of 12 subnets.  The layer 2 connection is
>> provides by our wireless ISP.  Our whole network is one VLAN and our IT
>> control layer3 address space.  Our ISP provided me with RO SNMP
>> community string for their devices that our network resides on.
>>
>> Question:  Will netdisco (being layer2) just see their devices as part
>> our our network and show us on a certain VLAN?  Is this going to break
>> autotopology?  Could I use the topology file and populate it with all
>> our routers "linked" together (thus making it look like one big LAN)?  I
>> don't know how many devices are between our buildings (they are many
>> miles apart) and I don't see, or care about our ISPs equipment.
>>
>> Thanks for your help.
>>
>> Jay Fluharty
>> Network Administrator
>> Brooke County Schools.
>>
>>
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