Category Gpon

Transaction Language 1 (TL1)

It is a TCP connection-based cross-vendor, cross-technology man-machine language, and is widely used to manage/Provisioning broadband access infrastructure .

Using TL1 we are passing input and output messages between Operations Support Systems (OSSs) and Network Elements (NEs) e.g OLT for purpose to configure services / Query status.

Traffic Flow : OSS System–Unified EMS of Vendor—NE (OLT Device)

TL1 Messages

The TL1 language consists of a set of messages. There are 4 kinds of messages:

1. Input message – This is the command sent by the user or the OSS.
2. Output/Response message – This is reply sent by the NE(Network Element) in response to an input message.
3. Acknowledgment message – This is an acknowledgment of the receipt of a TL1 input message and is sent if the response message will be delayed by more than 2 seconds.
4. Autonomous message – These are asynchronous messages (usually events or alarms) sent by the NE.

TL1 message structure

TL1 messages follow a fixed structure, and all commands must conform to it. However, the commands themselves are extensible and new commands can be added by NE vendors.

These are some of the message components:

• Target identifier (TID) & Source identifier (SID) – TID/SID is a unique name assigned to each NE. TID is used to route the message to an NE, SID is used to identify the source of an autonomous message.
• Access identifier (AID) – AID identifies an entity within an NE.
• Correlation tag (CTAG) & Autonomous correlation tag (ATAG) – CTAG/ATAG are numbers used to correlate messages.

TL1 example for ZTE OLT/ONT Services

1. LST-ONU::OLTID=172.0.0.1:CTAG::; //Query list of ONU
2. LST-ONU::OLTID=172.23.23.2,PONID=1-1-2-1:CTAG::;  //List of ONU by gpon port
3. LST-PORTQOS-TRAFFICPRF::DID=172.23.23.2,PID=1-1-2-1:1::; //List of onu traffic profile
4. LST-ONUSTATE::OLTID=10.184.9.30,PONID=1-1-7-11,ONUIDTYPE=LOID,ONUID=1902048116:CTAG::;
5. LST-VLANID::DID=10.61.94.33:5::; //Show vlan
6. CHG-ONU-STAT-PON::DID=10.10.10.1,OID=1-1-4-1-1:CTAG::STATUS=Disable; //shutdown port
7. ADD-ONU::OLTID=10.10.10.1,PONID=1-1-7-1:CTAG::AUTHTYPE=LOID,ONUID=1908092401,ONUNO=17,NAME=ABC_New FTTH,ONUTYPE=ZTE-F670;

TL1 Example For Huawei OLT/ONT service

1. DEL-ONT::DEV=CMI09001G00,FN=0,SN=1,PN=9,ONTID=2:1::;  //delete ONT/ONU
2. ADDONT::DEV=BKK44001G00,FN=0,SN=15,PN=8,ONTID=17:6::NAME=BKK44001G00/0/15/8/17, LINEPROF=Home_5M,SRVPROF=SRV_ABC,AUTH=LOID_ONCEON,LOID=1111111111,VAPROFILE=ABC; Adding an ONU   //Add ONT/ONU

Broadband remote access server

BRAS can also be referred to as a broadband network gateway or border network gateway (BNG).

Its responsible for assigning network parameters such as IP addresses to the clients. The BRAS is also the first IP hop from the client to the Internet.

The BRAS is also the interface to authentication, authorization and accounting systems. It Provides user Point-to-Point Protocol (PPP) sessions and PPP session termination and routes traffic onto the backbone.

It lets carriers fine tune their service offerings as well as charge for traffic on a per-byte basis.

Example :

Brief Traffic Flow

BRAS(PPOE Server)–PE—OLT—ONT(PPOE Client)

ONT is getting WAN internet IP address from BRAS device via PPOE protocol. While OLT & PE devices just serving the purpose for MPLS & GPON infrastructure.

Below FTTH scenario ONT at home is getting IPv4 address assigned by BRAS device

10.234.135.219 gateway:10.234.255.254 (Assigned to WAN ip of ONT device at Home)

Internet PPOE :1500  uplink of ZTE OLT and PE device.

Configuration at BRAS side for assigning IP

ACS Auto-Configuration Server — software that manages devices remotely.

TR-069 (also known as CWMP or CPE WAN Management Protocol) is an Internet protocol based on XML/SOAP. It enables remote configuration of CPE (ONT).This Configuration is managed by a central server called an auto-configuration server (ACS).

How to connect a CPE to the ACS?

Few parameters to be configured on the CPE:

• CPE can learn about ACS through DHCP option 43,
• ACS URL: an Internet address of the ACS, which is accessible from the device.
• Periodic Inform Interval: defines a frequency of communication with the ACS.
• Username and password: verification data is optional. It depends on the ACS requirements and an expected security level.

ACS and CPE interoperate through the RPC method unique to TR069 protocol. CPE always start session with an “inform”RPC and also ACS May request session (execute RPC’s).

Below is Remote Procedure Calls List in CWMP v1.1 :

Events

• An event is an indication that something of interest has happened that requires the CPE to notify the ACS via an Inform request Below Some common Events:
• The ACS URL is saved or changed on the device or the device is reset to factory settings (the device communicates it as BOOTSTRAP).
• The device responds to the ACS request for immediate connection (the device communicates it as CONNECTION REQUEST).
• The device is reset or is reconnected to the power supply (the device communicates it as BOOT).
• The device wants to report execution of previously ordered download or upload methods (the device communicates it as TRANSFER COMPLETE).

The manufacturer of the device can add custom events that will also make the device connect to the ACS.

 Fiber optic splitter, also referred to as optical splitter, or beam splitter, Its Waveguide optical power distribution device.

Passive device used for light beam to be divided two or more light beams.(one port divide to two or more ports).

How Does  Splitter Work?

When the light signal transmits in a single-mode fiber, the light energy cannot entirely concentrate in the fiber core. A small amount of energy will be spread through the cladding of fiber. That is to say, if two fibers are close enough to each other, the transmitting light in an optical fiber can enter into another optical fiber. Therefore, the reallocation technique of optical signal can be achieved in multiple fibers. And this is how fiber optic splitter comes into being.

Splitter types

• FBT : Fused Biconic Taper Is used especially for instances where the split configuration is smaller (1:2, 1:4, 2:2, etc.).
• PLC : Planar Lightwave Circuit ,Waveguides are fabricated using lithography onto a silica glass substrate,offer accurate and even splits with minimal loss.It is more compact and is lower cost with greater degrees of splitting.