Throughput Issues when using NV2 linked at GB, to rb1100AH

RouterOS General
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Now this has been an ongoing issue for YEARS now. If I have to, I’ll draw it out on a diagram, it is EASILY replicate-able. Any PtP using NV2, linked up at 1Gb, going to a 1Gb interface router such as rb1100AH, then out the LAN at 100mb, throughput drops 50%.

We are now using a GB switch, when I FORCE it to 100Mb on the interface going to WAN interface, I speedtest ~99mb to the AP’s behind it linked at 100Mb. However, when WAN is linked at 1Gb, only about 50mb throughput. I can push 100% to the WAN, the problem appears to be in the transition between 1Gb WAN, to 100Mb LAN

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Is this with a TCP or UDP speed test? Is it specific to NV2 - if you use nstream or 802.11 do you still get the same results? If you eliminate the RB1100 do you still get the same results (eg: radio going straight to WAN at 1gb / 100mb)?

Have you managed to do any traffic analysis - for example monitoring TCP retransmissions, MTU/fragmentation issues, etc?

Out of curiosity, have you tried applying a 100mbps traffic queue on the NV2 link to see if this makes any difference?

Rich