Security Software

When a application tring to search againest DPS, it's failed with "Connection reset by peer" error .Following is the access log of DPS.
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[07/May/2009:03:48:39 +0200] - CONNECT - INFO - conn=1074039 client=153.88.247.15:2979 server=ecditna03-1:389 protocol=LDAP
[07/May/2009:03:48:39 +0200] - SERVER_OP - INFO - conn=1074039 op=8 SEARCH base="ou=idm,ou=apps,ou=external,o=ericsson" scope=2 filter="(objectclass=groupOfUniqueNames)" attrs="*" s_msgid=1756 s_conn=ecditna03-2:45765
[07/May/2009:03:48:39 +0200] - OPERATION - INFO - conn=1074039 op=8 SEARCH RESPONSE err=0 msg="" nentries=5 etime=0
[07/May/2009:03:53:40 +0200] - DISCONNECT - INFO - conn=1074039 reason="other" msg="Exception caught while polling client connection LDAP.153.88.247.15.2979 -- java.io.IOException: Connection reset by peer"
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[07/May/2009:03:48:29 +0200] - CONNECT - INFO - conn=1074027 client=153.88.247.15:2974 server=ecditna03-1:389 protocol=LDAP
[07/May/2009:03:48:29 +0200] - OPERATION - INFO - conn=1074027 op=8 msgid=9 SEARCH base="ou=External,o=Ericsson" scope=2 filter="(objectclass=inetorgperson)" attrs="EriCA-AttesterNL EriCA-EmploymentForm EriCA-KeyRecoveryNL-Auth EriCA-NL-Auth EriCA-NLOTP-Admin EriCA-NLOTP-User EriCA-accountExpires c cn departmentNumber displayName eriCompanySynch eriCountry eriCountryCode eriEmployeeStatus eriExpired eriIsManager eriMasterDomain eriOpOrgUnitAbbreviation eriOpOrgUnitIdentifier eriOpOrgUnitName eriOperationalManager eriPartner eriPartnerTrigram eriPwSynchDate eriSignType eriSignum eriSignumStatus facsimileTelephoneNumber givenName isMemberOf l mail memberOf mobile ou sn telephoneNumber title uid uidNumber "
[07/May/2009:03:59:39 +0200] - OPERATION - INFO - conn=1074027 op=8 SEARCH RESPONSE err=0 msg="" nentries=45379 etime=670012
[07/May/2009:04:04:39 +0200] - DISCONNECT - INFO - conn=1074027 reason="other" msg="Exception caught while polling client connection LDAP.153.88.247.15.2974 -- java.io.IOException: Connection reset by peer"


No special error from the error log file. Only one client has this problem. Is this beacuse of the system drop the idle connection of this cilent?
$ uname -a
SunOS ecdiala03-2 5.10 Generic_120011-14 sun4v sparc SUNW,Sun-Fire-T200