I just installed centos 6.3 freshly and noticed the following:
[root@localhost user1]# cat /etc/redhat-release CentOS release 6.3 (Final)
[root@localhost user1]#
[root@localhost user1]# cat /proc/sys/net/core/rmem_max 131071
[root@localhost user1]# cat /proc/sys/net/core/rmem_default 229376
[root@localhost user1]# cat /proc/sys/net/core/wmem_max 131071
[root@localhost user1]# cat /proc/sys/net/core/wmem_default 229376
As you can see rmem_max is "Lesser " than rmem_default and wmem_max is "Lesser" than wmem_default.
As per my knowledge wmem_max and rmem_max should be more than default values ?
EDIT:
# cat /etc/redhat-release CentOS release 6.3 (Final)
# uname -a Linux localhost.localdomain 2.6.32-279.el6.x86_64 #1 SMP Fri Jun 22 12:19:21 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux
Bear in mind that the value of rmem_default should be no greater than rmem_max (/proc/sys/net/core/rmem_max); if need be, increase the value of rmem_max.
if it is "2.6.32-279" then it is a bug, upgrade it. Should be either equal or more as you mentioned in the link.