I recall being able to go past 8000 with send_frame_size and recv_frame_size parameters and things worked stably up to something like 8044, but it did eventually hard cap out.
Couple extra samples sometimes helps out :) > On August 3, 2017 at 1:14 PM Ian Buckley via USRP-users > <usrp-users@lists.ettus.com> wrote: > > Paolo, > Thats a fundamental H/W limitation of the current FPGA design. Long story > short, it would have been inefficient to support an MTU slightly larger than > a 2^N size. It’s also a pretty conservative number in terms of a an MTU that > works for 99% of Hosts and network gear. > -Ian > > > > > On Aug 3, 2017, at 6:32 AM, Paolo Palana via USRP-users > <usrp-users@lists.ettus.com mailto:usrp-users@lists.ettus.com > wrote: > > > > > > Hello to all the mailing list. > > > > I'm playing around with my X310, as far as I can understand the > > maximum ethernet frame size supported by this device is 8000. > > (in fact in x300_impl.hpp there is this constant static const > > size_t X300_10GE_DATA_FRAME_MAX_SIZE = 8000;). > > > > Because I'm curious I made an attempt and modified this value to > > 9710 (the maximum MTU size for my linux box) and I put some cout inside the > > function > > determine_max_frame_size (in x300_impl.cpp). This function seems to > > negotiate the MTU between the X310 and the host. > > > > What I observerd is that if I keep > > X300_10GE_DATA_FRAME_MAX_SIZE=8000 determine_max_frame_size negotiate the > > rigth MTU > > > > recv_test_frame_size = 6004 recv_size = 6004 > > recv_test_frame_size = 7004 recv_size = 7004 > > recv_test_frame_size = 7504 recv_size = 7504 > > recv_test_frame_size = 7752 recv_size = 7752 > > recv_test_frame_size = 7876 recv_size = 7876 > > recv_test_frame_size = 7940 recv_size = 7940 > > recv_test_frame_size = 7972 recv_size = 7972 > > recv_test_frame_size = 7988 recv_size = 7988 > > recv_test_frame_size = 7996 recv_size = 7996 > > recv_test_frame_size = 8000 recv_size = 8000 > > > > while if I set X300_10GE_DATA_FRAME_MAX_SIZE=9710 when > > determine_max_frame_size try to send more than 8912 bytes, happens like a > > brick on the X310, > > no more ethernet traffic is possible (even ICMP). This sounds > > really like somewhere there is a buffer of 8192 bytes in length. > > > > I made also an attempt to modify the MTU parameter on the noc_shell > > and axi_wrapper modules without results. > > > > Now I perfectly understand that I want to use the device, let me > > say, out of specification, but I want to ask if there is way to have a MTU > > larger than 8000. > > > > Thank you in advance for your attention. > > > > Best > > > > _______________________________________________ > > USRP-users mailing list > > USRP-users@lists.ettus.com mailto:USRP-users@lists.ettus.com > > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > > > > > > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >
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