Wednesday August 01, 2007 17:11:46 Send IKE Q1(QINIT) : 192.168.1.0 --> 192.168.3.0
Wednesday August 01, 2007 17:11:46 Receive IKE INFO : 192.168.121.221 --> 192.168.125.10
Wednesday August 01, 2007 17:11:46 Receive IKE INFO : 192.168.121.221 --> 192.168.125.10
Wednesday August 01, 2007 17:11:46 Receive IKE (INFO) : delete 192.168.121.221 -> 192.168.125.10 phase 1
Wednesday August 01, 2007 17:11:46 Send IKE (INFO) : delete [192.168.1.0|192.168.125.10]-->[192.168.121.221|192.168.3.0] phase 2
Wednesday August 01, 2007 17:11:46 IKE phase2 (IPSec SA) remove : 192.168.1.0 <-> 192.168.3.0
Wednesday August 01, 2007 17:11:46 inbound SPI = 0x3c000010, outbound SPI = 0x0
Wednesday August 01, 2007 17:11:46 Send IKE (INFO) : delete 192.168.125.10 -> 192.168.121.221 phase 1
Wednesday August 01, 2007 17:11:46 IKE phase1 (ISAKMP SA) remove : 192.168.125.10 <-> 192.168.121.221
Wednesday August 01, 2007 17:11:46 Send IKE M1(INIT) : 192.168.125.10 --> 192.168.121.221
Wednesday August 01, 2007 17:11:47 Receive IKE M2(RESP) : 192.168.121.221 --> 192.168.125.10
Wednesday August 01, 2007 17:11:47 Try to match with ENC:3DES AUTH:PSK HASH:MD5 Group:Group2
Wednesday August 01, 2007 17:11:47 Send IKE M3(KEYINIT) : 192.168.125.10 --> 192.168.121.221
Wednesday August 01, 2007 17:11:47 Receive IKE M4(KEYRESP) : 192.168.121.221 --> 192.168.125.10
Wednesday August 01, 2007 17:11:48 Send IKE M5(IDINIT) : 192.168.125.10 --> 192.168.121.221
Wednesday August 01, 2007 17:11:48 Receive IKE M6(IDRESP) : 192.168.121.221 --> 192.168.125.10
Wednesday August 01, 2007 17:11:48 IKE Phase1 (ISAKMP SA) established : 192.168.121.221 <-> 192.168.125.10
Wednesday August 01, 2007 17:11:48 Send IKE Q1(QINIT) : 192.168.1.0 --> 192.168.3.0
Wednesday August 01, 2007 17:11:48 Receive IKE INFO : 192.168.121.221 --> 192.168.125.10
Wednesday August 01, 2007 17:11:48 Receive IKE INFO : 192.168.121.221 --> 192.168.125.10


Wednesday August 01, 2007 17:12:13 Send IKE M3(KEYINIT) : 192.168.125.10 --> 192.168.121.221
Wednesday August 01, 2007 17:12:13 Receive IKE M4(KEYRESP) : 192.168.121.221 --> 192.168.125.10
Wednesday August 01, 2007 17:12:14 Send IKE M5(IDINIT) : 192.168.125.10 --> 192.168.121.221
Wednesday August 01, 2007 17:12:14 Receive IKE M6(IDRESP) : 192.168.121.221 --> 192.168.125.10
Wednesday August 01, 2007 17:12:14 IKE Phase1 (ISAKMP SA) established : 192.168.121.221 <-> 192.168.125.10
Wednesday August 01, 2007 17:12:14 Send IKE Q1(QINIT) : 192.168.1.0 --> 192.168.3.0

перенастроил все заново. Внимательно сверяя настройки. ВОт что вышло

Соединение установлено:
Wednesday August 01, 2007 17:12:14 IKE Phase1 (ISAKMP SA) established : 192.168.121.221 <-> 192.168.125.10

Только проверьте что на ZyXel не используется DPD или других чатсных протоколов поддержания соединения.