tp_dummy is an interface utilized by Zero Phishing, and I believe this interface was added in R82. It will be shown as non-accelerated in the output of fwaccel stat, as it terminates local traffic at the gateway ("local connection" F2F reason). You can take a closer look at its SecureXL status with fwaccel if tp_dummy. From the R82 Threat Prevention Administration Guide under Enabling the Zero Phishing Software Blade:
When you enable Zero Phishing with the automatic settings, a new interface is created in the Security Gateway infrastructure in GaiaClosed, called tp_dummy or tp_dummy_X (for VSX). This is a dummy interface which is intentionally isolated from external access. This interface has a constant IP and allows Zero Phishing clients to communicate with the Security Gateway. When automatic settings are used, the client communicates with the Security Gateway using the FQDN "zero-phishing.iaas.checkpoint.com".
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