i have errors in log zabbix proxy and server:
dotneft # tail -f /var/log/zabbix/zabbix_proxy.log | grep c2r3ups01.test.ru
14513:20111026:152804.038 SNMP item [apc.BatteryTemperature] on host [c2r3ups01.test.ru] failed: another network error, wait for 15 seconds
14513:20111026:152824.153 temporarily disabling SNMP checks on host [c2r3ups01.test.ru]: host unavailable
14510:20111026:152924.166 enabling SNMP checks on host [c2r3ups01.test.ru]: host became available

but i don't see in tcpdump queries:
zabbix-trunk # tcpdump -np host 10.100.52.8
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 96 bytes
15:25:12.276711 IP 10.100.11.45.44628 > 10.100.52.8.161: C=public GetRequest(36) .1.3.6.1.4.1.318.1.1.10.2.3.2.1.4[|snmp]
15:25:12.325343 IP 10.100.52.8.161 > 10.100.11.45.44628: C=public GetResponse(41) .1.3.6.1.4.1.318[|snmp]
15:25:49.613001 arp who-has 10.100.52.1 tell 10.100.52.8
15:27:03.381601 IP 10.100.11.45.46681 > 10.100.52.8.161: C=public GetRequest(34) .1.3.6.1.4.1.318.1.1.1.4.2.4.0[|snmp]
15:27:03.416751 IP 10.100.52.8.161 > 10.100.11.45.46681: C=public GetResponse(39) .1.3.6.1.4.1.318[|snmp]
15:27:04.407535 IP 10.100.11.45.59624 > 10.100.52.8.161: C=public GetRequest(34) .1.3.6.1.4.1.318.1.1.1.7.2.6.0[|snmp]
15:27:04.445123 IP 10.100.52.8.161 > 10.100.11.45.59624: C=public GetResponse(39) .1.3.6.1.4.1.318[|snmp]
15:27:12.534674 IP 10.100.11.45.33600 > 10.100.52.8.161: C=public GetRequest(34) .1.3.6.1.4.1.318.1.1.1.2.2.8.0[|snmp]
15:27:12.572059 IP 10.100.52.8.161 > 10.100.11.45.33600: C=public GetResponse(39) .1.3.6.1.4.1.318[|snmp]
15:27:13.549699 IP 10.100.11.45.36081 > 10.100.52.8.161: C=public GetRequest(34) .1.3.6.1.4.1.318.1.1.1.2.2.1.0[|snmp]
15:27:13.582344 IP 10.100.52.8.161 > 10.100.11.45.36081: C=public GetResponse(39) .1.3.6.1.4.1.318[|snmp]
15:27:14.576940 IP 10.100.11.45.49594 > 10.100.52.8.161: C=public GetRequest(34) .1.3.6.1.4.1.318.1.1.1.2.2.3.0[|snmp]
15:27:14.610833 IP 10.100.52.8.161 > 10.100.11.45.49594: C=public GetResponse(41) .1.3.6.1.4.1.318[|snmp]
15:27:16.609383 IP 10.100.11.45.44065 > 10.100.52.8.161: C=public GetRequest(34) .1.3.6.1.4.1.318.1.1.1.3.2.4.0[|snmp]
15:27:16.643131 IP 10.100.52.8.161 > 10.100.11.45.44065: C=public GetResponse(39) .1.3.6.1.4.1.318[|snmp]
15:27:17.645861 IP 10.100.11.45.41856 > 10.100.52.8.161: C=public GetRequest(34) .1.3.6.1.4.1.318.1.1.1.3.2.1.0[|snmp]
15:27:17.681825 IP 10.100.52.8.161 > 10.100.11.45.41856: C=public GetResponse(40) .1.3.6.1.4.1.318[|snmp]
15:27:20.701552 IP 10.100.11.45.50608 > 10.100.52.8.161: C=public GetRequest(34) .1.3.6.1.4.1.318.1.1.1.4.1.1.0[|snmp]
15:27:20.739801 IP 10.100.52.8.161 > 10.100.11.45.50608: C=public GetResponse(39) .1.3.6.1.4.1.318[|snmp]
15:27:28.021190 IP 10.100.11.45 > 10.100.52.8: ICMP echo request, id 14907, seq 0, length 76
15:27:28.024483 IP 10.100.52.8 > 10.100.11.45: ICMP echo reply, id 14907, seq 0, length 76
15:27:29.023347 IP 10.100.11.45 > 10.100.52.8: ICMP echo request, id 14907, seq 1, length 76
15:27:29.026740 IP 10.100.52.8 > 10.100.11.45: ICMP echo reply, id 14907, seq 1, length 76
15:27:30.023728 IP 10.100.11.45 > 10.100.52.8: ICMP echo request, id 14907, seq 2, length 76
15:27:30.034321 IP 10.100.52.8 > 10.100.11.45: ICMP echo reply, id 14907, seq 2, length 76
15:29:24.123489 IP 10.100.11.45.36498 > 10.100.52.8.161: C=public GetRequest(34) .1.3.6.1.4.1.318.1.1.1.7.2.3.0[|snmp]
15:29:24.165822 IP 10.100.52.8.161 > 10.100.11.45.36498: C=public GetResponse(39) .1.3.6.1.4.1.318[|snmp]

apc.BatteryTemperature have oid .1.3.6.1.4.1.318.1.1.1.2.2.2.0