Hi! VLAN's SVI should be different on each node (and that is, clearly, out of scope of vsx sync): say, as example, SVI of VLAN id x on VSX Primary 10.0.0.251, SVI of VLAN id x on VSX Secondary 10.0.0.252 and, finally (that's the parameter that is normally synchronized) the IP of the Active Gateway 10.0.0.254...that's just an example.
Have a look at the latest VSX Best Practices guide.
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Davide Poletto
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