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Jumbo Frames

Article ID: 121
Last updated: 18 Feb, 2009
Views: 8910
Jumbo Frames Rating: 10.0000 / 10
Votes: 1
Posted: 03 Feb, 2009
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Updated: 18 Feb, 2009
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Symptom:  When trying to set  the MTU value of 9000, it claims it's a wrong value.
Problem: Trying to enable jumbo frames on an Intel82573V Ethernet controller from the console
CTRL-ALT-W
Tuning Options
Jumbo Frames Config
Solution:
you may want to try a smaller value.
It looks as the Intel 82573V does not support Jumbo frames.
I found this on Intel’s website, the note is for the Intel 82573V
 
 
2.7.1 Jumbo Frame Support1
Ethernet controllers support jumbo frames to increase performance and decrease CPU utilization.
By default, Ethernet controllers might receive packets with a maximum size of 1522 bytes.
If large frame reception is enabled by the Receive Control Register (RCTL), Ethernet controllers support jumbo packet reception of up to 9014 bytes (9234 byes for the 82571EB/82572EI/631xESB/ 632xESB). On the transmit size, jumbo packets are always supported by the Ethernet controllers. It is the responsibility of the software driver to initiate jumbo packets only when it is configured to do so.
Note: For the 82573L, the packet buffer size must be at least the size of the maximum packet size.
Furthermore, in order to reach wire speed the transmit packet buffer size must be at least twice the size of the maximum packet size. The total transmit and receive packet buffer size is 32 KB.
Therefore, in case wire speed performance is important, the programmer should enable 9 KB packets. In the case of 9 KB, the transmit buffer size could be set to 18 KB while the receive buffer size could be set to 14 KB.
 
1. Not applicable to the 82573E/82573V.
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