With 11g (10.3.4 WLS), coherence is now built into many applications.  I’ve been noticing errors in my OSB logs like these:

####<10/03/2011 10:45:40 AM EST> <Warning> <Coherence> <osb-jeos> <osb_server1> <Logger@324239121 3.6.0.4> <<anonymous>> <> <583c1
0bfdbd326ba:-8c38159:12e9d02c829:-8000-0000000000000003> <1299714340643> <BEA-000000> <Oracle Coherence 3.6.0.4 (member=n/a): Unic
astUdpSocket failed to set receive buffer size to 714 packets (1023KB); actual size is 12%, 89 packets (127KB). Consult your OS do
cumentation regarding increasing the maximum socket buffer size. Proceeding with the actual value may cause sub-optimal performanc
e.> 
####<10/03/2011 10:45:40 AM EST> <Warning> <Coherence> <osb-jeos> <osb_server1> <Logger@324239121 3.6.0.4> <<anonymous>> <> <583c1
0bfdbd326ba:-8c38159:12e9d02c829:-8000-0000000000000003> <1299714340650> <BEA-000000> <Oracle Coherence 3.6.0.4 (member=n/a): Pref
erredUnicastUdpSocket failed to set receive buffer size to 1428 packets (1.99MB); actual size is 6%, 89 packets (127KB). Consult y
our OS documentation regarding increasing the maximum socket buffer size. Proceeding with the actual value may cause sub-optimal p
erformance.> 
####<10/03/2011 10:45:40 AM EST> <Warning> <Coherence> <osb-jeos> <osb_server1> <Logger@324239121 3.6.0.4> <<anonymous>> <> <583c1
0bfdbd326ba:-8c38159:12e9d02c829:-8000-0000000000000003> <1299714340659> <BEA-000000> <Oracle Coherence 3.6.0.4 (member=n/a): Mult
icastUdpSocket failed to set receive buffer size to 714 packets (1023KB); actual size is 12%, 89 packets (127KB). Consult your OS 
documentation regarding increasing the maximum socket buffer size. Proceeding with the actual value may cause sub-optimal performa
nce.> 

I was able to “fix” this on my ubuntu system by adding the following lines to the /etc/sysctl.conf file:

# Setup networking for coherence
# maximum receive socket buffer size, default 131071
net.core.rmem_max = 2000000
# maximum send socket buffer size, default 131071
net.core.wmem_max = 1000000
# default receive socket buffer size, default 65535
net.core.rmem_default = 2524287
# default send socket buffer size, default 65535
net.core.wmem_default = 2524287