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diff --git a/_gpon/g_984_series.md b/_gpon/g_984_series.md index 81f24ef..df8e9e1 100644 --- a/_gpon/g_984_series.md +++ b/_gpon/g_984_series.md @@ -19,7 +19,7 @@ The information on this page is taken from the GPON standard and information fro # General Concepts[^zyxel] -- Bit Rate: 1.2 Gbps Upstream; 2.4 Gbps Downstream. +- Bitrate: 1.2 Gbps Upstream; 2.4 Gbps Downstream. - Physical Reach: Max physical distance between OLT and ONT. - Differential Fiber Distance: Distance between closest and farthest ONT from OLT (max = 20km) @@ -35,7 +35,7 @@ The information on this page is taken from the GPON standard and information fro | **1.24416** | **2.48832** | | 2.48832 | 2.48832 | -1.24416 Gbps up, 2.48832 Gbps down is the mainstream speed combination supported at current time. +1.24416 Gbps up, 2.48832 Gbps down is the most supported speed combination at current time. # GPON Terminology @@ -46,7 +46,7 @@ The information on this page is taken from the GPON standard and information fro * 0 .. 253 Assignable * 254 Reserved * 255 Broadcast/unassigned -* OLT assigns to an ONU during the ONU's activation using the PLOAM channel. +* The OLT assigns an id to any ONU during the ONU's activation using the PLOAM channel. * ONU-ID is unique across the PON and remains valid until the ONU is powered off, deactivated by the OLT or moves itself into an inactive state. ## Allocation Identifier (Alloc-ID)[^zyxel] @@ -61,9 +61,9 @@ The information on this page is taken from the GPON standard and information fro A Transmission Container (T-CONT) is an ONU object representing a group of logical connections that appear as a single entity for the purpose of upstream bandwidth assignment on the PON. * Bandwidth assignment and QoS control are performed in every T-CONT by fixed and dynamic methods. * There are 5 types of T-CONT Traffic Descriptors: - * Type 1: fixed bandwidth type. - * Type 2 and Type 3: guaranteed bandwidth types. - * Type 4: best-effort type. + * Type 1: fixed bandwidth; + * Type 2 and Type 3: guaranteed bandwidth; + * Type 4: best-effort; * Type 5: mixed type, involving all bandwidth types and bearing all services | Type 1 | Type 2 | Type 3 | Type 4 | Type 5 | @@ -74,9 +74,9 @@ A Transmission Container (T-CONT) is an ONU object representing a group of logic * For TR-156 and TR-167, each T-CONT represents a traffic class * Each ONU is assigned at least one Alloc-ID which is equal to that ONU's ONU-ID and may be assigned additional Alloc-IDs per the OLT's discretion. - * Typically have 4 T-CONTs, supporting 4 traffic classes, plus one T-CONT for OMCI -* Default Alloc-ID is used to carry the upstream PLOAM and OMCC traffic and may carry user data traffic. -* OLT schedules upstream traffic across all ONUs according to the priority and weight assigned to each T-CONT, and their buffer occupancy. Other bandwidth assignment mechanisms are available, for example fixed bandwidth, assured bandwidth, and nonassured bandwidth[^broadbandforum]. + * Typically have 4 T-CONTs, supporting 4 traffic classes, plus an extra one for OMCI +* The default Alloc-ID is used to carry the upstream PLOAM and OMCC traffic and may carry user data traffic. +* The OLT schedules upstream traffic across all ONUs according to the priority and weight assigned to each T-CONT, and their buffer occupancy. Other bandwidth assignment mechanisms are available, for example fixed bandwidth, assured bandwidth, and nonassured bandwidth[^broadbandforum]. ## Dynamic Bandwidth Allocation (DBA) @@ -84,7 +84,7 @@ A Transmission Container (T-CONT) is an ONU object representing a group of logic {% include image.html file="quick-start/pon_dba.jpg" alt="PON DBA Abstraction" caption="PON DBA Abstraction" %} -Dynamic Bandwidth Allocation (DBA) is a technique by which traffic bandwidth in a shared telecommunications medium can be allocated on demand and fairly between different users of that bandwidth. And it is performed on the upstream traffic[^zyxel]. +Dynamic Bandwidth Allocation (DBA) is a technique by which traffic bandwidth in a shared telecommunications medium can be allocated on demand and fairly between different users of that bandwidth. It is performed on the upstream traffic[^zyxel]. With DBA, the OLT assesses the bandwidth needs of the ONUs in real time and allocates upstream PON capacity accordingly[^broadbandforum]. @@ -110,10 +110,10 @@ Payload - User data ### GPON Encapsulation -GPON use two layers of encapsulation: +GPON uses two layers of encapsulation: 1. TDM and Ethernet frames are wrapped into GTC Encapsulation Method (GEM) frames, which have a GFP-like format (derived from Generic Frame Procedure ITU G.7401). -The main purpose of the GEM frame is to provide a frame-oriented service, as an alternative to ATM, in order to efficiently accommodate Ethernet and TDM frames. With GEM, all traffic is mapped across the GPON network using a variant of SONET/SDH GFP. GEM supports a native transport of voice, video, and data without an added ATM or IP encapsulation layer[^medium],[^fs]. +The main purpose of the GEM frame is to provide a frame-oriented service, as an alternative to ATM, in order to efficiently accommodate Ethernet and TDM frames. With GEM, all traffic is mapped across the GPON network using a variant of SONET/SDH GFP. GEM natively supports transportation of voice, video, and data without an added ATM or IP encapsulation layer[^medium],[^fs]. 2. ATM and GEM frames are both encapsulated into GTC frames that are finally transported over the PON[^medium],[^fs]. ITU-T G.984 defines GEM as the only data transport scheme for GPON. Bandwidth allocation in GPON grants individual transmission opportunities to the ONU's traffic-bearing entities on the timescale of a single GTC frame[^zyxel]. @@ -144,32 +144,32 @@ PCBd consists of the GTC header and BWmap: {% include image.html file="quick-start/downstream-multiplexing.png" alt="Downstream multiplexing (shaded GEM port indicates multicast)" caption="Downstream multiplexing (shaded GEM port indicates multicast)" %} -1. OLT sends Ethernet frames from Uplink ports to the GPON service processing module based on configured rules to the PON ports. -2. GPON service processing module then encapsulates the Ethernet frames into GEM port data packets for downstream transmission. +1. The OLT sends Ethernet frames from Uplink ports to the GPON service processing module based on configured rules to the PON ports. +2. The GPON service processing module then encapsulates the Ethernet frames into GEM port data packets for downstream transmission. 3. GPON transmission convergence (GTC) frames that contain GEM PDUs are broadcast to all ONT/ONUs connected to the GPON port. -4. ONT/ONU filters the received data based on the GEM port ID contained in the GEM PDU header and retains the data only significant to the GEM ports on this ONT/ONU. -5. ONT decapsulates the data and sends the Ethernet frames to the end users via service ports. +4. The ONT/ONU filters the received data based on the GEM port ID contained in the GEM PDU header and only retains data significant to the GEM ports on this ONT/ONU. +5. The ONT decapsulates the data and sends the Ethernet frames to the end users via service ports. ### Upstream[^zyxel],[^broadbandforum],[^cisco] {% include image.html file="quick-start/gpon-upstream.jpg" alt="GPON Upstream" caption="GPON Upstream" %} -In the Upstream the GEM traffic is carried over one or more T-CONTs. The OLT receives the transmission associated with the T-CONT and the frames are forwarded to the GEM TC adapter and then the GEM client. +In the Upstream channel, GEM traffic is carried over one or more T-CONTs. The OLT receives the transmission associated with the T-CONT and the frames are forwarded to the GEM TC adapter and then the GEM client. - Use Time Division Multiple Access (TDMA) for upstream data transmission w/o AES encryption. * Distance between the OLT and ONT/ONU is measured (Ranging): - * OLT starts the process on an ONU when the ONU first registers with the OLT and obtains round trip delay (RTD) of the ONU. Based on the RTD, the other key components are identified: + * The OLT starts the process on an ONU when the ONU first registers with the OLT and obtains round trip delay (RTD) of the ONU. Based on the RTD, other key components are identified: * Calculation of the physical reach of that specific ONU, as this OLT requires a proper equalization delay (EqD) for each ONU based on physical reach. - * RTC and EqD synchronize data frames sent by all ONUs + * RTC and EqD synchronize data frames sent by all ONUs. * Time slots are allocated based on distance. In order to prevent data conflict (collisions), the OLT must be able to precisely measure the distance between itself and each ONU to provide a proper time slot to facilitate data upstream. This allows the ONUs to send data at specified time slots, to prevent issues upstream. This process is achieved through a technique called ranging. - * ONT/ONU sends traffic upstream based on granted time slot. + * The ONT/ONU sends traffic upstream based on the granted time slot. - Dynamic Bandwidth Allocation (DBA) enables the OLT to monitor in real-time, congestion, bandwidth usage, and configuration. - Traffic multiplexing is distributed. -- The OLT grants the upstream bandwidth allocation. +- The OLT grants upstream bandwidth allocation. - The ONU traffic-bearing entities are identified by their Allocations IDs. -- The alloc-IDs are multiplexed in time as specified by the bandwidth-map (given by the OLT in the downstream frame). -- Within the bandwidth allocation, the ONU uses the GEM Port-IF as key to identify upstream GEM frames. -- Each upstream frame contains the content carried by one or more T-CONT/T-CONTs. +- Alloc-IDs are multiplexed in time as specified by the bandwidth-map (provided by the OLT in the downstream frame). +- Within its bandwidth allocation, the ONU uses the GEM Port-IF as key to identify upstream GEM frames. +- Each upstream frame contains the content carried by one or more T-CONTs. - All ONUs connected to a GPON port share the upstream bandwidth. - All ONUs send their data upstream at their own time slots based on bandwidth map (BWmap) requirements. - Each ONU reports the status of data to be sent to the OLT by use of upstream frames. OLT uses DBA to allocate upstream time slots to ONUs and sends updates in each frame. @@ -178,7 +178,7 @@ In the Upstream the GEM traffic is carried over one or more T-CONTs. The OLT rec {% include image.html file="quick-start/upstream-multiplexing.png" alt="Upstream multiplexing" caption="Upstream multiplexing" %} -1. ONT/ONU send Ethernet frames to GEM ports based on configured rules that map service ports and GEM ports. +1. ONT/ONUs send Ethernet frames to GEM ports based on configured rules that map service ports and GEM ports. 2. GEM ports encapsulate the Ethernet frames into GEM PDUs and add these PDUs to T-CONT queues based on rules that map GEM ports and T-CONT queues. 3. T-CONT queues use time slots based on DBA, then transmit upstream GEM PDUs to the OLT. 4. OLT decapsulates the GEM PDU, the original Ethernet frame is now seen. @@ -228,7 +228,7 @@ Resolves Ethernet frames and directly maps the data of Ethernet frames into the * Establish and release connections with the ONT. * Manage the UNIs on the ONT. * Request configuration information and performance statistics. - * Autonomously alert of events, such as a link failure. + * Autonomously alert events, such as a link failure. - Key Points: * Protocol runs over a GEM connection between the OLT and ONT. * GEM connection is established while the ONT initializes. @@ -236,40 +236,40 @@ Resolves Ethernet frames and directly maps the data of Ethernet frames into the ### Management Information Base (MIB) and Management entities (ME's)[^arsat] -A way of MIB (Management Information Base) formed by Management Entities (ME's) is used to fully describe the ONU configuration, status and several other actions +MIBs (Management Information Base) formed by Management Entities (MEs) are used to fully describe the ONU configuration, status and several other actions. -OMCI constitute the protocol in order to support the set of actions performed over ONU to create; delete and other set of actions on those ME's +OMCI constitutes the protocol which supports the set of actions performed over an ONU to create, delete and more on those MEs - A Managed Entity (ME) is composed of attributes, actions and notifications defining its characteristics. - Managed Entity (ME Class Value) - Purpose of the entity - - Autonomously instantiated by ONU or explicitly created by OLT + - Autonomously instantiated by the ONU or explicitly created by the OLT - Relationship(s) with other managed entities - Attributes: Attribute Definition - - ME id: This attribute provides a unique number for each instance of this managed entity. - - List of attributes. Attribute Number within ME Determined by the Order in Which Attributes are Listed + - ME id: provides a unique number for each instance of this managed entity. + - List of attributes: Attribute Number within ME determined by the order in which attributes are listed - Actions: operations that may be performed on the entity (Create/Get/Set/Test, etc.) - Notifications (Alarm, AVC, TCA, Test Result) -- There can be multiple instances of a Managed Entity. Each instance has the same attributes, actions and notifications even though the values of the attributes may be different from each other. +- There can be multiple instances of any Managed Entity: each instance has the same attributes, actions and notifications even though the values of the attributes may be different from one another. ### VEIP and PPTP[^huaweiveip],[^cdatatec] -According to the application, ONU can be divided into six types, namely SFU (Single Family Unit) ONU, HGU (Home Gateway Unit) ONU, MDU (Multi-Dwelling Unit) ONU, SBU (Single Business Unit) ONU, MTU (Multi-Tenant Unit) ONU and CBU (Cellular Backhaul Unit) ONU. However, only SFU (Single Family Unit) ONU and HGU (Home Gateway Unit) ONU are used by the end-users in practical application. +According to the application, ONU can be divided into six types, namely SFU (Single Family Unit) ONU, HGU (Home Gateway Unit) ONU, MDU (Multi-Dwelling Unit) ONU, SBU (Single Business Unit) ONU, MTU (Multi-Tenant Unit) ONU and CBU (Cellular Backhaul Unit) ONU. However, only SFU (Single Family Unit) ONU and HGU (Home Gateway Unit) ONU are used by the end-users in practical applications. -HGU ONU takes the Virtual Ethernet interface point (VEIP). Virtual Ethernet interface point (VEIP) as an OMCI administrative domain and a non-OMCI administrative domai (like TR-069). At the switchover point of the data plane, the ME can be managed only through the OMCI and is visible to the non-OMCI management domain, but not manageable. Similarly, all UNI-side modules under the VEIP are invisible to and cannot be managed by the OMCI. They are visible and manageable only to the non-OMCI management domain. In addition, each ONU should have only one VEIP. +HGU ONU takes the Virtual Ethernet Interface Point (VEIP) as an OMCI administrative domain and a non-OMCI administrative domain (like TR-069). At the switchover point of the data plane, the ME can be managed only through the OMCI and is visible to the non-OMCI management domain, but not manageable. Similarly, all UNI-side modules under the VEIP are invisible to and cannot be managed by the OMCI. They are visible and manageable only to the non-OMCI management domain. In addition, each ONU should have only one VEIP. -When the ONU uploads the MIB, the ONU reports only the mandatory MEs and supported optional MEs. It does not report the MEs related to LOID authentication, performance monitoring, and T-CONT MEs of the OMCC channel. +When the ONU uploads MIBs, the ONU reports only the mandatory MEs and supported optional MEs. It does not report the MEs related to LOID authentication, performance monitoring and T-CONT MEs of the OMCC channel. -The ONU should be used according to the device type and report either VEIP or PPTP during MIB upload. The SFU only uses and reports PPTP. VEIP should not be used. HGUs can only use and report VEIPs. PPTP should not be used. The OLT determines the ONU type based on the ONU Type attribute in ME:ONU Capability. Only one VEIP is allowed in each HGU. ONU will report VEIP or PPTP (Physical Path Termination Point) when MIB is uploaded according to the type of the device, while HGU can only use and report VEIP rather than PPTP. OLT will judge the type of ONU devices according to the attribution of ONU type in ONU capability. +The ONU should be used according to the device type and report either VEIP or PPTP during MIB upload. The SFU only uses and reports PPTP. VEIP should not be used. HGUs can only use and report VEIPs. PPTP should not be used. The OLT determines the ONU type based on the ONU Type attribute in ME:ONU Capability. Only one VEIP is allowed in each HGU. ONUs will report VEIP or PPTP (Physical Path Termination Point) when MIB is uploaded according to the type of the device, while HGUs can only use and report VEIP rather than PPTP. The OLT will judge the type of each ONU device according to the ONU type attribute in ONU capability. {% include image.html file="quick-start/veip.jpg" alt="Service Process of HGU ONU" caption="Service Process of HGU ONU" %} -SFU ONU only supports the OMCI management domain. PPTP is what SFU uses and reports, while VEIP is not available. The processing mode of OMCI configured data flow is different from that of RG flow. For OMCI data flow, there is a one-to-one mapping between the GEM port on the WAN side and the UNI port on the LAN side. All data packets can pass through without MAC address learning or forwarding. Wireless interfaces are not allowed in OMCI. +SFU ONUs only support the OMCI management domain. PPTP is what SFU uses and reports, while VEIP is not available. The processing mode of OMCI configured data flow is different from that of RG flow. For OMCI data flow, there is a one-to-one mapping between the GEM port on the WAN side and the UNI port on the LAN side. All data packets can pass through without MAC address learning or forwarding. Wireless interfaces are not allowed in OMCI. -SFU ONU is designed for a single family unit with broadband access terminal function without a more complex home gateway function from the perspective of application and ONU capacity. SFU ONU, mainly used in FTTH scenarios, has 1 or 4 Ethernet interfaces and is available for Ethernet / IP services, optional VoIP services (built-in IAD), or CATV services. +SFU ONUs are designed for a single family unit with broadband access terminal function without a more complex home gateway function from the perspective of application and ONU capacity. SFU ONUs, mainly used in FTTH scenarios, typically have 1 or 4 Ethernet interfaces and are available for Ethernet / IP services, optional VoIP services (built-in IAD), or CATV services. -SFU ONU works under the bridging mode (layer 2 of ISO model), supports multiple VLAN functions, and its Ethernet port can be configured and managed by OLT through OMCI / OAM. Combined with a home gateway, SFU ONU is good at providing strong service capability. +SFU ONUs work under bridging mode (layer 2 of ISO model), support multiple VLAN functions, and their Ethernet port can be configured and managed by the OLT through OMCI / OAM. Combined with a home gateway, SFU ONUs are good at providing strong service capability. <hr> |