Changing MTU size

Hi,

Has anyone successfully changed the MTU size to something larger than 1500
and run successfully? We have an application that needs to use an MTU of
16k over Gig-E. We’re running QNX 6.3 on a x86 with a 82544 Enet chip.
We’ve tried changing the params via io-net/devn-i82544 but they don’t seem
to take effect. The packets still seem to get fragmented into 1500 byte
chunks.

Thanks,
Rick

To do that your driver must support ‘jumbo frames’ feature. I doubt that QNX
driver does it, but ‘check with your sales representative’ :wink:

“Rick Walsh” <rick.walsh@leitch.com> wrote in message
news:d19pe5$nch$1@inn.qnx.com

Hi,

Has anyone successfully changed the MTU size to something larger than 1500
and run successfully? We have an application that needs to use an MTU of
16k over Gig-E. We’re running QNX 6.3 on a x86 with a 82544 Enet chip.
We’ve tried changing the params via io-net/devn-i82544 but they don’t seem
to take effect. The packets still seem to get fragmented into 1500 byte
chunks.

Thanks,
Rick

Igor Kovalenko wrote:

To do that your driver must support ‘jumbo frames’ feature. I doubt that QNX
driver does it, but ‘check with your sales representative’ > :wink:

Max size of JUMBO packets is 9018 bytes as specified in if_ether.h

Armin


“Rick Walsh” <> rick.walsh@leitch.com> > wrote in message
news:d19pe5$nch$> 1@inn.qnx.com> …

Hi,

Has anyone successfully changed the MTU size to something larger than 1500
and run successfully? We have an application that needs to use an MTU of
16k over Gig-E. We’re running QNX 6.3 on a x86 with a 82544 Enet chip.
We’ve tried changing the params via io-net/devn-i82544 but they don’t seem
to take effect. The packets still seem to get fragmented into 1500 byte
chunks.

Thanks,
Rick

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Thanks for the tips. We’ve got to the point where QNX can send a jumbo
frame, but it can’t receive one.


“Armin Steinhoff” <a-steinhoff@web.de> wrote in message
news:d1a2pa$cd$1@inn.qnx.com

Igor Kovalenko wrote:
To do that your driver must support ‘jumbo frames’ feature. I doubt that
QNX
driver does it, but ‘check with your sales representative’ > :wink:

Max size of JUMBO packets is 9018 bytes as specified in if_ether.h

Armin



“Rick Walsh” <> rick.walsh@leitch.com> > wrote in message
news:d19pe5$nch$> 1@inn.qnx.com> …

Hi,

Has anyone successfully changed the MTU size to something larger than
1500
and run successfully? We have an application that needs to use an MTU
of
16k over Gig-E. We’re running QNX 6.3 on a x86 with a 82544 Enet chip.
We’ve tried changing the params via io-net/devn-i82544 but they don’t
seem
to take effect. The packets still seem to get fragmented into 1500 byte
chunks.

Thanks,
Rick

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