The Nicrxtxqs Keyword - Neoware e140 - Thin Client User Manual

The mPXELdr Configuration File
The NICRxTxQs
Keyword
268 Keywords
server returned to the station in its DHCPACK reply to the DHCP
request emitted by the PXE boot prom.
If set to I, the regular DHCPINFORM method is used. This is the
default.
Syntax:
NICRxTxQs = <n1/n2>
Examples:
NICRxTxQs = 8/4
NICRxTxQs = 1/1
Default value: None
Warning: This option implements a work around for a few and
limited number of technical issues related to very specific PXE
implementations. It should only be used when such a case has been
clearly and unambiguously identified.
Both and must be in the range 1..127.
n1 n2
The PXE firmware internally use buffer queues for packet transmis-
sion and reception. Those queues allow the unattended transmission
and reception of data packets at times when the CPU is busy doing
some other work. Upon initialization, mPXELoader queries the PXE
firmware for the size of the transmit and receive queue for the PXE
NIC. During the boot sequence, PXE never requests from the server
more packets than the Tx queue can handle. Conversely, it never
attempts to send in a row more packets than the transmit queue can
handle.
Unfortunately, some PXE implementations return invalid values to
mPXELoader. When those values are very obviously invalid, mPX-
ELoader detects this and assumes valid and safe (and somehow
slow) values. But if those values are both invalid and plausible,
mPXELoader takes them for granted and uses them. This can result
in mPXELoader requesting more packets from the server than the
NIC can handle and buffer, and data packet drops, timeouts, retries,
etc. The result is a failing (or extremely slow) first boot phase. This
has been specifically reported in the case when mPXELoader was
running in a Microsoft Virtual Server or Microsoft Virtual PC vir-
tual machine, using the MS simulated PXE NIC.