Juniper serial number 'BUILTIN' causes device*Changed notifications

[pstolpe]

Juniper devices seems to report modules with BUILTIN, serial number.
When there are multiple Juniper devices in NAV we get an device*Changed notification each time as they all refer to the same device in the device table. This occurs since NAV 5.5.0.

Examples from the database

nav=# select * from module where model='BUILTIN';
 moduleid | deviceid | netboxid | module |      name       |  model  |               descr                | up | downsince
----------+----------+----------+--------+-----------------+---------+------------------------------------+----+-----------
     2008 |    18141 |     1110 |        | MIC-3D-20GE-SFP | BUILTIN | PIC: 10x 1GE(LAN) SFP @ 1/3/*      | y  |
     2009 |    18141 |     1111 |        | MIC3-100G-DWDM  | BUILTIN | PIC: 1X100GE DWDM CFP2-ACO @ 5/0/* | y  |

nav=# select * from device where serial='BUILTIN';
 deviceid | serial  | hw_ver | fw_ver |   sw_ver    |         discovered
----------+---------+--------+--------+-------------+----------------------------
    18141 | BUILTIN | REV 24 |        | 20.4R3-S2.6 | 2016-10-25 12:40:51.807121

[lunkwill42]

This seems to be a pre-existing issue with Juniper in NAV, that has only now been made blatantly visible and noisy by the new device*Notice family of alerts:

Through ENTITY-MIB::entPhysicalTable, Juniper switches tend to report internal modules as field-replaceable units, all with the same serial number: BUILTIN.

These would not be registered as proper modules in NAV had they not been reported as field-replaceable (which they are not!). The actual problem here is in Juniper's implementation, which reports 'true' as the value of ENTITY-MIB::entPhysicalIsFRU.

This sort of tomfoolery isn't protected against by NAV. As a result, you will have one single Device with the serial number BUILTIN registered in NAV, and any number of Juniper switch modules will point to this same Device entry (likely most of them). Since these modules do not actually represent the same physical device, the various switches and routers will report different SW/HW/FW revisions, which all will be reported as changes to the same Device entry (and it changes almost every time an inventory is polled for any Juniper device).

The proper course of action would be to report this upstream as a JunOS bug.

I can only suggest a workaround for NAV: Implement a serial number blacklist and refuse to register any module/device that has a serial number of BUILTIN.

[lunkwill42]

Closed by #2492