Principles of choosing supervisory channels of NG WDM devices


Almost all OTU boards on NG WDM devices support ESC, but SC2 boards are also configured on live networks to support OSC. When both supervisory methods are available, certain principles to choose which to use should be followed.
Root cause: None
If both OSC and ESC are available between two NEs, the priority of DCC channels in use are as follows: 1. GCC12_1; GCC12_9; D4-D12; D1-D3; pilot-tone DCC2. 2. If the available DCC channels have the same bandwidth, follow the sequential orders that DCC channels were identified by the NE instead of the DCC channel ID in ascending order. Generally, this is related to the order of the boards going online, namely, the NE preferentially choose the DCC channel of the board that goes online first to deliver monitoring messages. Note: Some OTU boards such as L4G can also use D1 to D3 channels by modifying the service type to SDH at the WDM side.
Suggestion and conclusion:
The priority of ESC monitoring channels of NG WDM is higher than OSC. When both OSC and ESC are available, the supervisory messages are preferentially delivered through ESC.

Other related questions:
Querying of the reset records of NG WDM devices
Run the :errlog command to query reset records of NEs and the :mon-get-errlog:bid command to query reset records of boards.

Types of supervisory channels supported by NG WDM equipment
The DCC channel bandwidth supported by NG WDM equipment is represented by the number of loadable 64 bytes. The following lists the DCC channels supported by NG WDM equipment and the bandwidth: D1-D3 3 bytes D4-D12 9 bytes GCC0 3 bytes GCC12_9 9 bytes GCC12_18 18 bytes Pilot-tone DCC Irrelevant to byte or bandwidth Note: 1. For the OTU boards whose WDM-side service type is SDH, the DCC channel type is D1-D3. Channels D4-D12 are not supported. 2. SC2/SC1 boards support two DCC channel types: D1-D3 and D4-D12. In normal situations, both DCC channel types can be used to transmit monitoring information. After ASON is enabled, D4-D12 can be used only as physical channels to transmit the ASON protocol. 3. For the OTU board of the OTN frame structure, three channel types are supported: GCC0, GCC12_9, and GCC12_18. For OTN boards with 2.5G rates, GCC0 and GCC12_9 are allocated. For OTN boards with 5G and 10G, GCC0 and GCC12_18 are allocated. The bandwidth provided by GCC0 is 3 bytes, which is the same as the bandwidth of D1-D3. It is the GCC0 byte in the OTUk overhead in the OTN frame structure. The bandwidth provided by GCC12_9 and GCC12_18 are 9 and 18 bytes respectively. They are the GCC1 and GCC2 bytes without various bandwidth in the ODUk overhead in the OTN frame structure. 4. Pilot-tone DCC is special. By coupling RF signals and service signals, pilot-tone DCC uses RF signals to carry monitoring information. Therefore, no byte or bandwidth is involved in pilot-tone DCC.

Commands used to query reset records of an NG WDM device
Run the :errlog command to query the reset records of an NE. Run the :mon-get-errlog:bid command to query the reset records of a board.

Description on the GCC byte mode of NG WDM products
Question: In the OTN architecture, the ESC mode is adopted. Sometimes, the GCC byte mode needs to be set using the :cm-set-fiberport command. The last parameter of this command indicates the channel rate. 13 denotes three-byte GCC0, 14 denotes the GCC12_9 byte, and 15 denotes the GCC12_18 byte. How are three-byte GCC0, GCC12_9, and GCC_18 calculated? Root cause: None Answer: 1. The channel rate is an equivalent rate. Three-byte GCC0 indicates that the bandwidth provided by GCC0 is 3 x 64K, and GCC12_9 indicates that the total bandwidth provided by GCC1 and GCC2 is 9 x 64K. In the OTN architecture, GCC0 is of two bytes, and the frame structure is always 4 x 4080 bytes. 2. At the 2.5G rate, the bandwidth of GCC0 is calculated using the following formulas: Frame frequency = 2.5G/(4 x 4080 x 8) Bandwidth of GCC0 = 2x frame frequency x 8 Therefore, the approximate bandwidth is as follows: 320K = 5 x 64K Likewise, at the 5G and 10G rates, the approximate bandwidths are 10 x 64K and 20 x 64K respectively. (The length of an OTN frame is fixed, whereas the frame frequency varies.) Due to the limit on CPU channels, the bandwidth provided by GCC0 must be reduced so that the equipment can be used like the previous equipment. That is, GCC0 is used as three bytes only. To be specific, the supervisory bandwidth provided by GCC0 is 3 x 64K. 3. According to the preceding method, at the 2.5G rate, GCC1 and GCC2 together provide 10 x 64K bandwidth. That is, GCC1 and GCC2 are used as nine bytes. GCC1 and GCC2, which are always bound together when used, provide 20 x 64K bandwidth at the 5G rate and 40 x 64K bandwidth at the 10G rate. Suggestion and conclusion: The OTN-framed OTU board supports DCC types GCC0, GCC12_9, and GCC12_18. The OTN 2.5G board supports GCC0 and GCC12_9, and the OTN 5G and OTN 10G boards support GCC0 and GCC12_18.

Method used to check the condition of NG WDM service channels
A meter can be used to check the condition of NG WDM service channels. A PRBS test can also be used to check the condition at deployment.

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