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Chapter 3. Networking

QFQ queuing discipline

In Red Hat Enterprise Linux 6.3, the tc utility has been updated to work with the Quick Fair Scheduler (QFQ) kernel features. Users can now take advantage of the new QFQ traffic queuing discipline from userspace. This feature is considered a Technology Preview.

rdma_bw and rdma_last utilities deprecated

The rdma_bw and rdma_lat utilities (provided by the perftest package) are now deprecated and will be removed from the perftest package in a future update. Users should use the following utilities instead: ib_write_bw, ib_write_lat, ib_read_bw, and ib_read_lat.

Enhancements in the configuration tool for IBM System z network devices

With Red Hat Enterprise Linux 6.3, the System z qethconf tool provides information messages when a change of attributes did not work as expected.

IPv6 support for qetharp tool for IBM System z

Red Hat Enterprise Linux 6.3 adds IPv6 support to the qetharp tool for inspection and modification of the ARP cache of HiperSockets (real and virtual) operated in layer 3 mode. For real HiperSockets, the tool queries and shows the IPv6 address, and for guest LAN HiperSockets, it queries and shows IPv6 to MAC address mappings.

Maximum number of session slots

In Red Hat Enterprise Linux 6.3, NFSv4 introduces a module/kernel boot parameter, nfs.max_session_slots, which sets the maximum number of session slots the NFS client will attempt to negotiate with the server. This limits the number of simultaneous RPC requests that the client can send to the NFSv4 server. Note that setting this value higher than max_tcp_slot_table_limit has no effect.