Support on the 7210 was introduced in SR OS 9.0R1.
Bear in mind that the ifIndex value is needed by some versions of 5620 SAM to build a layer-2 topology map using LLDP.
To see more detail:
*A:7750# show port 4/1/4 ethernet lldp remote-info
==============================================================================
Link Layer Discovery Protocol (LLDP) Port Information
==============================================================================
Port 4/1/4 Bridge nearest-bridge Remote Peer Information
-------------------------------------------------------------------------------
Remote Peer Index 2 at timestamp 05/10/2018 02:56:18:
Supported Caps : bridge router
Enabled Caps : bridge router
Chassis Id Subtype : 4 (macAddress)
PortId Subtype : 5 (interfaceName)
Port Id : 47:69:67:61:62:69:74:45:74:68:65:72:6E:65:74:30:2F:33:
2F:30
"GigabitEthernet0/3/0"
Port Description : to-7750-4-1-4
System Name : switch.lab
System Description : Huawei Versatile Routing Platform Software
VRP (R) software, Version 8.100 (CX600
V800R007C10SPC100)
Copyright (C) 2012-2015 Huawei Technologies Co., Ltd.
HUAWEI CX600-M2F