[CAnet - news] Jumbo frames for HPC computing and networking

For more information on this item please visit the CANARIE CA*net 4 Optical
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 [Some interesting research on jumbo frames being carried out by Ruherford
research on CAnet 4 - BSA]

http://www.rutherford-research.ca/rrx/9KApp/executiveSummary.php

The High Performance Computing community has already demonstrated that the
use of jumbo packets, IP packets exceeding 1500 bytes, offers an undeniable
performance advantage (typically a factor of 2 at 1 Gbps and much more at
higher rates), particularly when transferring large amounts of data. While
the use of jumbo packets might seem a wizard's tuning trick, it represents a
logical and immediately valuable benefit to grid computing. Further, it
becomes a requirement for scalability as networks move to 10 Gbps and
beyond. However, though the entire core and many of our GigaPoP networks are
now jumbo enabled, very few of our campus networks support jumbo packets. We
are creating the case, through performance analysis, for incrementally jumbo
enabling research networks and in order to offer some insight into the
different levels of performance benefit anticipated for distributed
applications, such as collaborative visualization, massive data transfer,
and distributed file systems. Concurrently we are also working closely with
the academic community, in Canada, and the U.S., from the corporate
perspective, to enhance awareness of subtle path MTU discovery issues.

Notably the project team is using a set of lightpaths provided by CA*net 4
to do the testing.

Our initial pilot project phase one explores the effect of packet size
variation, on key mission critical advanced network applications, for the
HPC community. The primary test is to explore potential ability, to
dynamically interact with visualizations, hosted on remote servers, as a
function of packet dynamics, over a well characterized path. The test bed
includes TCP transport across gigabit Ethernet sites, of increasing RTT,
using SGI's Vizserver platform, on an Onyx 3000 server, with both SGI and
Linux workstations running Vizserver clients. Preliminary tests indicate
network performance in the order of 400 megabits per second, with
significant potential for improvement. Further testing is required, in order
to characterize the effect of modifying parameters, and identifying the
hierarchy of bottlenecks, leading to effective optimization. Phase two
preliminary testing is set to explore the packet dynamics of NFS version 4,
as a function of packet size, and critical tuning parameters over TCP.
Similarly we expect increased packet size may have a dramatic effect on
performance. In a 2004 white paper SGI reports in the order of 25 megabytes
per second over local gigabit Ethernet LAN, using optimized NFS, with an MTU
of 1512 bytes. One of the key factors of NFS has been end node fragmentation
and reassembly, which is severely detrimental to performance. We plan to
demonstrate optimized NFS performance over 9000 byte MTU gigabit Ethernet
WAN with a block size of 8192 bytes, leading to increased non fragmentation
flow between hosts, and vastly improved throughput, possibly approaching
local SAN over fibre channel. In addition, we will be looking at the
effective utilization levels of both the network, and the end-hosts, to
identify the relative contributions that each has on the overall apparent
application performance.





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those  of the CANARIE board or management.



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