Article number
000004321
Affected Versions
All
Source Hypervisor
All
Target Hypervisor
All

How many TCP sessions Zerto creates for replication

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Summary

For network load/security reasons, an Administrator would want to know how many TCP connections the VRA creates during its replication process.

Steps

Here are all VRA connections it creates during the replication process:

ZVM - VRA control - 1
ZVM - VRA checkpoints - 1

The VRA - VRA connections are a full graph – all are connected to all.

For each pair of VRAs:
VRA1 -> VRA2 control - 1
VRA2 -> VRA1 control - 1

If there's a replicating volume between VRA1 -> VRA2 then will be also 8 data sockets (another 8 if there's also replication between VRA2 -> VRA1).
 
So the formula is:
Number of VRAs - N
Number of pairs - P (=N*(N-1)/2)
Number of replicating pairs - R (R<=P*2)

Number of TCP connections = 2N+2P+8R
Where 2N are connections inside the LAN and 2P+8R are over WAN.