High Memory utilization observed in Solarwind SNMP Manager.

You're probably polling the wrong OID. For v9-11 it's one of these two depending on what you're after;

TMM Mem Usage sysStatMemoryUsed (.1.3.6.1.4.1.3375.2.1.1.2.1.45)

Host Mem Usage sysHostMemoryUsed (.1.3.6.1.4.1.3375.2.1.7.1.2)

That was taken from info here: http://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/bigip_tmos_concepts_11_0_0/tmos_snmp.html?sr=322550131042852.

More info for per TMM statistics: http://support.f5.com/kb/en-us/solutions/public/9000/500/sol9524.html