v7.1rc3 [development] is released!

msatter · September 8, 2021, 8:47pm

In case someone still doesn’t understand the problem. I won’t bother with downgrading to 6.x for some nice copy/paste comparison, so you’ll just need to trust me on the fact, that this will work perfectly on 6.x - but you (mikrotik) yourself confirmed, that you’ve repeated the problem on your side, and you’ve fixed this in one of 6.49 betas so are you not fixing this on purpose in ROS7 or what gives?

> /ip address/print 
Columns: ADDRESS, NETWORK, INTERFACE
# ADDRESS            NETWORK         INTERFACE   
0 10.248.1.82/30     10.248.1.80     sfp-sfpplus1

> /interface/ethernet/print detail 
(...)
10 R  name="sfp-sfpplus1" default-name="sfp-sfpplus1" mtu=1500 l2mtu=1500 mac-address=[redacted] orig-mac-address=[redacted] arp=enabled arp-timeout=auto loop-protect=default loop-protect-status=off loop-protect-send-interval=5s 
      loop-protect-disable-time=5m auto-negotiation=no advertise="" full-duplex=yes tx-flow-control=off rx-flow-control=off speed=1Gbps bandwidth=unlimited/unlimited sfp-rate-select=high fec-mode=auto sfp-shutdown-temperature=95C 

> /ping 10.248.1.81 size=1500 do-not-fragment 
  SEQ HOST                                     SIZE TTL TIME       STATUS                                                                                                                                                                                                    
    0 10.248.1.81                              1500  64 155us     
    1 10.248.1.81                              1500  64 153us     
    sent=2 received=2 packet-loss=0% min-rtt=153us avg-rtt=154us max-rtt=155us 

> /ping 10.248.1.81 size=1501 do-not-fragment 
  SEQ HOST                                     SIZE TTL TIME       STATUS                                                                                                                                                                                                    
    0                                                              packet too large and cannot be fragmented                                                                                                                                                                 
    1                                                              packet too large and cannot be fragmented

> /interface/ethernet/set sfp-sfpplus1 l2mtu=4090 mtu=4000
> /ping 10.248.1.81 size=1500 do-not-fragment 
  SEQ HOST                                     SIZE TTL TIME       STATUS                                                                                                                                                                                                    
    0 10.248.1.81                              1500  64 157us     
    1 10.248.1.81                              1500  64 152us     
    sent=2 received=2 packet-loss=0% min-rtt=152us avg-rtt=154us max-rtt=157us 

/ip/address> /ping 10.248.1.81 size=1501 do-not-fragment 
  SEQ HOST                                     SIZE TTL TIME       STATUS                                                                                                                                                                                                    
    0 10.248.1.81                                                  timeout                                                                                                                                                                                                   
    1 10.248.1.81                                                  timeout                                                                                                                                                                                                   
    sent=2 received=0 packet-loss=100%

The problem different. Under v6 you could restart the SFP and it would allow an higher MTU.

Now it appears you can’t increase the MTU higer than 1500 and so the PPPoE has to git in that MTU by using a lower MTU than 1500.

If you set a higher MTU is that displayed in v7? And if so try it with restarting the SFP and if it now allows higher packet dizes.