Implementing basic LLDP server, should send port_id message

to each port once every 30 seconds.
* Additionally fixes the on-ward passing of LLDP frames through
the switch

The ports on the case are marked 1-8 so this should reflect that
rather than being 0-based

We can send the hostname as well, this can be dynamically allocated

Let's send the model as the system description as well

cmd_parser.c

@@ -16,6 +16,7 @@
 #include "rtl837x_stp.h"
 #include "rtl837x_igmp.h"
 #include "rtl837x_bandwidth.h"
+#include "rtl837x_lldp.h"
 #include "rtl837x_storm.h"
 #include "sfp.h"
 #include "dhcp.h"
@@ -32,6 +33,7 @@
 extern __code const struct machine machine;
 extern __xdata bool stp_enabled;
 extern __code const uint8_t log_to_phys_port[9];
+extern __xdata uint8_t lldp_enabled;
 
 extern volatile __xdata uint32_t ticks;
 extern volatile __xdata uint8_t sfr_data[4];
@@ -2024,6 +2026,14 @@ void cmd_parser(void) __banked
 			parse_ingress();
 		} else if (cmd_compare(0, "session")) {
 			parse_session();
+		} else if (cmd_compare(0, "lldp")) {
+			if (cmd_compare(1, "on")) {
+				print_string("LLDP enabled\n");
+				lldp_enabled = 1;
+			} else {
+				print_string("LLDP disabled\n");
+				lldp_enabled = 0;
+			}
 		}
 		else {
 			cmd_error("Unknown command\n");