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Migrating to 400G? Choosing the Right Option

Posted by Admin on 2023 Jul 16th

Migrating to 400G? Choosing the Right Option

Migrating to 400G? Choosing the Right Option

As customers deploy 400G connectivity, they are transitioning from 25/100G connectivity to 100/400G connectivity for the different tiers of the network. Before making a decision, you should carefully consider your technical needs and budget with these parameters in mind:

  • Reach: the distance you need to transmit data
  • Power Consumption
  • Flexibility – bending ratio. This is particularly important in tight spaces
  • Cost

Let us look at network transition at the different tiers.

ToR to Server/storage

Most customers use DAC (Direct Attach Copper) cables to connect a ToR to servers/storage as they are very cost-effective. We expect that to continue. Some customers may augment DAC with AOC (Active Optical Cables) to extend beyond 3m reach of 400G DAC cables.

Between ToR & Leaf

For 100G, most customers use AOC, SR4, BiDi or PSM4. We expect 100G-AOC customers to use 400G-AOC for up to 30m connectivity. We expect 100G-SR4 & 100G-BiDi customers to use 400G-SR8 and 400G-BiDi for up to 100m connectivity. We expect 100G-PSM4 customers to deploy 400G-DR4 to 400G-DR4 or 400G-DR4 to 4x100G-DR1 connectivity.

Between Leaf & Spine and Spine & DCI

For 100G, most customers use PSM4 or CWDM4. We expect them to move to 400G-DR4 for up to 500m and to 400G-FR4 or 400G-2FR4 for up to 2km connectivity. We expect 400G-DR4 volumes to be high, as it is being used in multiple tiers of a data center, where the number of switches is high.

Inter-DC Connectivity

For 100G, most customers use CWDM4, LR4 or Coherent optics depending on distance requirements. They will likely move to 400G-FR4, 400G-LR8/LR4 or 400G-ZR/ZR+ Coherent optics, depending on reach requirements. Customers often use MACsec on these links for privacy and security reasons.