Download the new RouterOS 6.12 release over the torrent network: http://www.mikrotik.com/download/routeros-ALL-6.12.torrent
Otherwise please visit http://www.mikrotik.com/download to pick exact version!

6.12 changelog:

*) l2tp - fixed "no buffer space available" problem;
*) ipsec - support IPv4 over IPv6 and vice versa;
*) pppoe - report correctly number of active links;
*) updated timezone information;
*) many fixes for CRS managed switch functionality - particularly improved VLAN support, port isolation, defaults;
*) added trunk support for CRS switches;
*) added policing support for CRS switches;
*) www - added support for HTTP byte ranges;
*) lte - provide signal strength using snmp and make 'info once' work in console;