[ofa-general] MTU in IPoIB

[Wiegers, Bert]

Hi,

In our default-setup we are using IPoIB. This is set up with a MTU of 65520

ib0       Link encap:UNSPEC  HWaddr 80-00-00-48-FE-80-00-00-00-00-00-00-00-00-00-00
          inet addr:10.75.107.32  Bcast:10.75.255.255  Mask:255.255.0.0
          inet6 addr: fe80::214:4fa4:d3ba:25/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:65520  Metric:1
          RX packets:9318 errors:0 dropped:0 overruns:0 frame:0
          TX packets:4197 errors:0 dropped:10 overruns:0 carrier:0
          collisions:0 txqueuelen:4096
          RX bytes:25032362 (23.8 Mb)  TX bytes:636320 (621.4 Kb)



Our dmesg on the other hand shows these hints:


ib_core: module not supported by Novell, setting U taint flag.
ib_mad: module not supported by Novell, setting U taint flag.
ib_mthca: module not supported by Novell, setting U taint flag.
mlx4_ib: module not supported by Novell, setting U taint flag.
mlx4_ib: Mellanox ConnectX InfiniBand driver v1.0 (April 4, 2008)
ib_ipath: module not supported by Novell, setting U taint flag.
cxgb3: module not supported by Novell, setting U taint flag.
iw_cxgb3: module not supported by Novell, setting U taint flag.
ib_umad: module not supported by Novell, setting U taint flag.
NET: Registered protocol family 10
lo: Disabled Privacy Extensions
IPv6 over IPv4 tunneling driver
ib_uverbs: module not supported by Novell, setting U taint flag.
ib_sa: module not supported by Novell, setting U taint flag.
ib_cm: module not supported by Novell, setting U taint flag.
ib_ipoib: module not supported by Novell, setting U taint flag.
ADDRCONF(NETDEV_UP): ib0: link is not ready
ib0: enabling connected mode will cause multicast packet drops
ib0: mtu > 2044 will cause multicast packet drops.
ib0: mtu > 2044 will cause multicast packet drops.
ib1: enabling connected mode will cause multicast packet drops
ib1: mtu > 2044 will cause multicast packet drops.
ib1: mtu > 2044 will cause multicast packet drops.
ib_addr: module not supported by Novell, setting U taint flag.
iw_cm: module not supported by Novell, setting U taint flag.
rdma_cm: module not supported by Novell, setting U taint flag.
ib_sdp: module not supported by Novell, setting U taint flag.
NET: Registered protocol family 27
qlgc_vnic: module not supported by Novell, setting U taint flag.
QLGC_VNIC: Initializing QLogic Corp. Virtual NIC (VNIC) driver version 1.3.0.0.4
rdma_ucm: module not supported by Novell, setting U taint flag.
scsi_transport_iscsi: module not supported by Novell, setting U taint flag.
Loading iSCSI transport class v2.0-869.
libiscsi: module not supported by Novell, setting U taint flag.
iscsi_tcp: module not supported by Novell, setting U taint flag.
iscsi: registered transport (tcp)
ib_iser: module not supported by Novell, setting U taint flag.
iscsi: registered transport (iser)
md: Autodetecting RAID arrays.
md: autorun ...
md: ... autorun DONE.
ib0: multicast join failed for ff12:401b:ffff:0000:0000:0000:ffff:ffff, status -11
ADDRCONF(NETDEV_CHANGE): ib0: link becomes ready
eth0: no IPv6 routers present
ib0: no IPv6 routers present



So should I limit the MTU to 2044?

Thanks.

Bert