To configure chassis cluster for SRX 1500 you can follow the same procedure as used for the SRX 1400. There is not much difference as far as configuration is considered to have chassis cluster for SRX 1500 in comparison to SRX 1400.
On the hardware level there is a dedicated control port on SRX 1500 to be used for control link. Also it cannot be configured like on SRX 1400 as well but it needs to be connected while configuring cluster on SRX 1500.
Thanks, Pulkit Bhandari
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