Hello together!

I've a NFS
server (cluster1=137.226.167.241) and a
client (cluster2=137.226.167.242) which should mount it's nfsroot from cluster1.

The linux-2.6.32 kernel on cluster2 shows this error during startup:
[ 528.982985] IP-Config: Complete:
[ 528.983049] device=eth0, addr=137.226.167.242, mask=255.255.255.224, gw=137.226.167.225,
[ 528.983299] host=cluster2, domain=, nis-domain=(none),
[ 528.983383] bootserver=255.255.255.255, rootserver=137.226.167.241, rootpath=
[ 528.983633] Looking up port of RPC 100003/2 on 137.226.167.241
[ 530.037059] e1000e: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: Rx
[ 530.056881] ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[ 564.002113] rpcbind: server 137.226.167.241 not responding, timed out
[ 564.002295] Root-NFS: Unable to get nfsd port number from server, using default
[ 564.002412] Looking up port of RPC 100005/1 on 137.226.167.241
[ 564.104137] VFS: Mounted root (nfs filesystem) on device 0:15.

Nevertheless it can mount the nfsroot finally.

But if I use kernel linux-2.6.39.4 on cluster2 it can't mount it's nfsroot:
[ 1133.736818] IP-Config: Complete:
[ 1133.736887] device=eth0, addr=137.226.167.242, mask=255.255.255.224, gw=137.226.167.225,
[ 1133.737090] host=cluster2, domain=, nis-domain=(none),
[ 1133.737204] bootserver=255.255.255.255, rootserver=137.226.167.241, rootpath=
[ 1134.819382] e1000e: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: Rx
[ 1134.839798] ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[ 1168.828804] VFS: Unable to mount root fs via NFS, trying floppy.
[ 1168.828958] VFS: Insert root floppy and press ENTER


It's the same with other newer kernels.
The portmap is running.
So what could be wrong there? Could someone of you help me, please?

Regards

PS:
My OS: Debian 6.0.3 (squeeze)
NFS server on custer1: nfs-kernel-server

I only want to add that the NFS-configuration of both kernels is the same:
linux-2.6.32:
CONFIG_NFS_FS=y
CONFIG_NFS_V3=y
CONFIG_NFS_V3_ACL=y
CONFIG_NFS_V4=y
# CONFIG_NFS_V4_1 is not set
CONFIG_ROOT_NFS=y
CONFIG_NFSD=m
CONFIG_NFSD_V2_ACL=y
CONFIG_NFSD_V3=y
CONFIG_NFSD_V3_ACL=y
CONFIG_NFSD_V4=y
CONFIG_NFS_ACL_SUPPORT=y
CONFIG_NFS_COMMON=y
CONFIG_NCPFS_NFS_NS=y

linux-2.6.39.4:
CONFIG_NFS_FS=y
CONFIG_NFS_V3=y
CONFIG_NFS_V3_ACL=y
CONFIG_NFS_V4=y
# CONFIG_NFS_V4_1 is not set
CONFIG_ROOT_NFS=y
# CONFIG_NFS_USE_LEGACY_DNS is not set
CONFIG_NFS_USE_KERNEL_DNS=y
# CONFIG_NFS_USE_NEW_IDMAPPER is not set
CONFIG_NFSD=m
CONFIG_NFSD_DEPRECATED=y
CONFIG_NFSD_V2_ACL=y
CONFIG_NFSD_V3=y
CONFIG_NFSD_V3_ACL=y
# CONFIG_NFSD_V4 is not set
CONFIG_NFS_ACL_SUPPORT=y
CONFIG_NFS_COMMON=y
CONFIG_NCPFS_NFS_NS=y

With nfsdebug as kernel argument I get this during startup of linux-2.6.39.4:
[ 407.571521] IP-Config: Complete:
[ 407.571589] device=eth0, addr=137.226.167.242, mask=255.255.255.224, gw=137.226.167.225,
[ 407.571793] host=cluster2, domain=, nis-domain=(none),
[ 407.571907] bootserver=255.255.255.255, rootserver=137.226.167.241, rootpath=
[ 407.572332] Root-NFS: nfsroot=/srv/nfs/cluster2
[ 407.572726] NFS: nfs mount opts='udp,nolock,addr=137.226.167.241'
[ 407.572927] NFS: parsing nfs mount option 'udp'
[ 407.572995] NFS: parsing nfs mount option 'nolock'
[ 407.573071] NFS: parsing nfs mount option 'addr=137.226.167.241'
[ 407.573139] NFS: MNTPATH: '/srv/nfs/cluster2'
[ 407.573203] NFS: sending MNT request for 137.226.167.241:/srv/nfs/cluster2
[ 408.617894] e1000e: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: Rx
[ 408.638319] ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[ 442.666622] NFS: failed to create MNT RPC client, status=-60
[ 442.666732] NFS: unable to mount server 137.226.167.241, error -60
[ 442.666868] VFS: Unable to mount root fs via NFS, trying floppy.
[ 442.667032] VFS: Insert root floppy and press ENTER

It seems to be a bug:
http://thread.gmane.org/gmane.linux.nfs/44596/