Hi, everybody!
Now, I continue to explain all problems with connecting ONU. Generally, there are 3 big possible problems: OLT, ODN, and ONU. In the last two posts, I explained problems with OLT. Today, I will start to explain problems with ODN and how we can fix it.
There are many problems with ODN. ODN is composed of three segments: feeder optical cable (from headend/CO to optical distribution point), distribution optical cable (from the optical distribution point to optical access point), and drop optical cable (from optical access point to ONU). In every segment of ODN, we can have problems.
There are the following problems:
Feeder/distribution/drop fibers are broken,
Dirty optical connectors,
Bent fibers,
Problem with optical splitters,
Connected connectors of different types,
Connected fibers of different types,
Bad splices,
Incorrectly designed networks or incorrectly realized networks.
1. Feeder/distribution/drop fibers are broken
This is one of the most problems at the ODN. If our feeder optical cable is broken, all ONUs are offline. If we have the same problem with distribution optical cable, one part of ONUs is offline. And the end, if the drop cable is broken, only one ONU is offline.
There are many methods for detecting these problems. The main and most reliable method of identifying the problem is used OTDR. With this instrument, we can check optical fibers and find where is a problem. OTDR will show us a point of brokenness and distance to it. We must have proper documentation, only with it we can measure, find and fix problems. After that, we have to send our technicians to fix it. The cable is most often collected from the route and splice in the optical closure.
When we test optical fibers with OTDR, optical fiber is longer than the optical cables, about 1%. We have to calculate that. Because every 10 km, the difference is 100 m. The reserves of optical cable that exist on the route should also be taken into account.
We can see alarms in our NMS (e.g. U2000 or eSight) and based on ONUs that are offline, we can conclude what is problem. Command on the OLT which we can use to check offline ONU is:
TEST(config-if-gpon-0/13)#display ont info 11 2
{ <cr>||<K> }:
Command:
display ont info 11 2
-----------------------------------------------------------------------------
F/S/P : 0/13/11
ONT-ID : 2
Control flag : active
Run state : offline
Config state : normal
Match state : match
DBA type : SR
ONT distance(m) : 984
ONT battery state : holding state
Memory occupation : 74%
CPU occupation : 1%
Temperature : 50(C)
Authentic type : SN-auth
SN : XXXXXXXXXX (HWTC-XXXXXX)
Management mode : OMCI
Software work mode : normal
Isolation state : normal
ONT IP 0 address/mask : X.X.X.X/X
Description : XXXXXXXX
Last down cause : loss
Last up time : 2001-12-17 17:27+01:00
Last down time : 2001-12-17 17:27+01:00
Last dying gasp time : 2001-12-17 17:27+01:00
ONT online duration : 27 day(s), 21 hour(s), 16 minute(s), 42 second(s)
Type C support : Not support
Interoperability-mode : ITU-T
-----------------------------------------------------------------------------
VoIP configure method : Default
-----------------------------------------------------------------------------
Line profile ID : 11
Line profile name : 0020m
-----------------------------------------------------------------------------
FEC upstream switch :Disable
OMCC encrypt switch :Off
Qos mode :PQ
Mapping mode :VLAN
TR069 management :Enable
TR069 IP index :0
....
Thank you!
For more information, please click:
ONU failure to go online – Problems with OLT (1)
ONU failure to go online – Problems with OLT (2)
ONU failure to go online – Problems with ODN (4)
ONU failure to go online – Problems with ODN (5)
ONU failure to go online – Problems with ODN (6)
ONU failure to go online – Problems with ODN (7)
ONU failure to go online – Problems with ONU (8)
