GEM ports description and usage in the GPON technology
GEM port description and usage in the GPON technology: First I might want to examine the GEM, What is the meaning of GEM? Individually I will zero in on the significant things identified with the GEM theme yet for that you need to peruse the whole article cautiously.
GEM-GPON Encapsulation Method-It is an association arranged information outline transport system that additionally supports discontinuity of the edges into variable estimated transmission information sections. GEM Port-GPON Encapsulation Method Port-It speaks to an intelligent association related to a particular traffic stream. GEM Port ID-GPON Encapsulation Method Port ID-It is 12-bit esteem allocated by the OLT to the individual sensible associations on the GPON interface. It is conveyed in the header of all the GEM edges of the consistent association.
In this article, I have attempted to depict nonexclusive insights regarding GEM Port usage in GPON technology. The GPON technology has introduced the GEM channel as a component of its GPON Transmission Convergence (GTC) layer. Truth be told the GEM channels convey variable-length outlines and likewise including Ethernet outlines. GEM channels are recognized by an interestingly appointed identifier, the GEM Port ID.
This identifier is appointed consequently by the endless supply of another channel and remains consistent during the whole life-pattern of the channel. GEM port IDs are virtual port identifiers that include a similar significance inside the ODN or include essentialness inside a single ODN. Each GPON interface for a given ONU can have a few GEM Ports. A GEM Port ID is extraordinary per GPON interface and speaks to a particular traffic stream or gathering of streams between the OLT and at least one ONUs.
GPON gives the authorization to the OLT (through OMCI) to determine the permitted transmission bearings (for example upstream and/or downstream) for every single GEM channel during the arrangement cycle. I might want to compose here about upstream and downstream.
Upstream-In:
The upstream traffic is gotten at the PE-Agg hub from the OLT on a VLAN. The VLAN is terminated at the PE-Agg and the traffic over this VLAN is planned into an IP-VPN in the IP/MPLS organization. The p-bit in the VLAN header is made an interpretation of into EXP pieces of the MPLS outline.
Downstream:
The downstream way the traffic streams from the internet towards the end client crossing the IP/MPLS organization, the GPON organization, and the Base Station. The traffic is gotten from the internet at the PDN-GW which checks the destination IP address of the IP bundle and determines the eNodeB. PDN-GW arrangement an IP Tunnel among it and the eNodeB across the IP/MPLS organization and GPON organization. It then sends the IP parcel over this passage in the wake of encapsulating it into an external IP bundle. The PDN GW sends this IP bundle to the PE-Agg facing it. The PE-Agg gets this IP bundle over a sub-interface which is arranged into an IP-VPN. It talks with the important VRF of the IP-VPN and determines the distant end PE-Agg. It then exemplifies the IP parcel into the MPLS outlines with EXP bits stamped and sends it to the applicable PE-Agg-hub.
When the traffic is gotten at the distant end PE-Agg hub facing the OLT, it utilizes the MPLS tag to determine the VPN affiliation. It then eliminates the MPLS tag and takes out the IP bundle. It then checks the destination IP address, talks with the significant VRF, and determines the outgoing interface. It then epitomizes the IP bundle with the VLAN header, interprets the DSCP-bits into the corresponding p-bits in the VLAN header, and sends it to the OLT.
The OLT gets the VLAN labeled with p-bit stamped traffic from the PE-Agg hub. With the assistance of the VLAN ID and p-nibbled, the OLT determines the outgoing Shelf/Rack/space/port/GEM port. The OLT sends the traffic to the pertinent PON port and GEM port.
The OLT determines the Traffic Class dependent on p-bit. The TC task for the traffic streams is applied by a classifier in the OLT.
Truth be told GPON permits or grant the OLT (through OMCI) to determine the permitted transmission headings (for example upstream and/or downstream) for every single GEM channel during the arrangement cycle of such sort of organization.
There are two kinds of GEM channels
Uni-directional GEM channel for broadcast traffic
Downstream (just) GEM channels – Such kinds of channels can be utilized to accomplish the transmitting downstream overflowed, broadcast, or multicast traffic. The casings are sent from the OLT into the GPON interface to all the ONUs and are then specifically sent to UNI interfaces by the ONUs that are designed with that GEM port. The utilization of this sort of GEM Channel is IPTV.
➤GEM channel for uni-directional transmission/multicast traffic
➤GEM channel for uni-directional transmission/multicast traffic
➤GEM channel for uni-directional
➤Bi-directional GEM channel for unicast traffic
PON frameworks are a transmission medium the downstream way, so all ONUs get all the downstream traffic for each GEM port, anyway, ONUs quietly dispose of traffic that isn't tended to for them. Also, AES encryption can be (and commonly is) applied over the bidirectional GEM ports. An alternate key for every ONU is utilized by the OLT for encryption and by the ONU for unscrambling.
There are 3 sorts of Bi-directional GEM channels.
➤One GEM port per UNI interface
➤Multiple GEM Ports per UNI interface
➤One GEM port for numerous UNI interfaces
Various GEM ports per UNI interface
In such an organization, GEM ports can likewise be utilized to separate among traffic classes. A given UNI interface may have a few GEM ports related to it that help diverse traffic classes. This kind of arrangement can be explained as follows: within the GPON interface, every single GEM Port conveys at least one traffic stream related to a particular traffic class going to a particular UNI interface on a particular ONU.
On UNI interface ingress, traffic is grouped into VLANs with different Ethernet needs dependent on various rules: actual port, VID, VLAN P-pieces, EtherType, and/or DSCP. Truth be told any combination of such kinds of standards can be utilized to determine the Ethernet need.
The VID and EtherType can be utilized to determine the new VID. When the traffic has been doled out a VLAN and Ethernet priority, these two Ethernet header segments are utilized to choose an upstream GEM Port with the goal that legitimate QoS can be applied to the streams. A GEM Port is planned into one and only one T-CONT. Also for departure, the ONU is liable for forwarding traffic got from GEM ports on the PON to the proper UNI interface.
➥Within the GPON, a bidirectional GEM Port MUST have the option to convey at least one traffic stream related to a similar traffic class going to a particular UNI interface on a particular ONU.
➥ OLT and the ONU MUST help one bi-directional GEM Port for each traffic class designed for a particular UNI interface on a particular ONU.
➤Multi GEM port
➤Different GEM ports per U interface
➤One GEM port for various UNI interfaces
For this situation, if different UNI interfaces have a place with a similar help, then these UNI interfaces are planned into a single GEM port. This situation is typically utilized for the EBU administrations.
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