Hey Silvia, thanks a lot for the insight! I did not expect this answer when asking this morning.
I am currently doing my master thesis [0] about IPv6 in fully programmable P4 switches (my hardware platform will be Barefoot Tofino in the end) - I assume this might be rather interesting for SBB, as it potentially can solve all problems [tm] in the network. Also I hear the 6.5 TBit/s switches are not that crazy expensive anymore. If you could get me in touch with the right people at SBB, this would be very interesting to talk about their network. Best, Nico [0] https://gitlab.ethz.ch/nicosc/master-thesis Silvia Hagen <silvia.ha...@sunny.ch> writes: > Hi guys > > Here's some info from SBB (I was working with them and just spoke with them > today). > > . They are aware of the problem. > . The problem only happens when someone uses smaller packet sizes (often when > using some tunnelling techniques). > . Currently the webserver is in an IPv4 zone, the Internet router is a Cisco > box which does 64 Translation. The packets go through an F5 LB to reach the > webserver. > . When the packets go out and the Cisco box asks for fragmention, it sends > the ICMP packet to the webserver. The F5 box has a bug, something with the > checksum goes wrong and the F5 discards the ICMP packet. > . They have had a neverending incident with F5 and F5 does not seem to be > able to fix that. SBB has given up on this incident. > > The plan: > . SBB is currently enabling IPv6 on the routing layer, plan to be > accomplished by summer 2019. > . Next step on the plan is to enable v6 out to the datacenter, with priority > on the webserver zone. So with that the problems should go away. > > SBB was attending the last swinog event in Switzerland. They will also come > again and they offered to have a talk if desired. I can connect to the right > person if you are interested. > > Thanks, Silvia > > > -----Ursprüngliche Nachricht----- > Von: swinog-boun...@lists.swinog.ch [mailto:swinog-boun...@lists.swinog.ch] > Im Auftrag von Nico Schottelius > Gesendet: Dienstag, 12. März 2019 10:33 > An: swinog@lists.swinog.ch > Betreff: [swinog] SBB.ch / IPv6 MTU / fragmentation problem > > > Good morning, > > is anyone from sbb.ch reading here? > > https://sbb.ch does not load on IPv6 for us. > It seems that packets > 1420 bytes are dropped inside the SBB network, > > Local PMTU / fragmentation seems to work, my local outgoing MTU is 1420. MTR > below. > > Best, > > Nico > > > [10:23] line:~% mtr -w -c1 -s 1500 sbb.ch > Start: 2019-03-12T10:24:17+0100 > HOST: line Loss% Snt Last Avg Best Wrst StDev > 1.|-- 2a0a:e5c1:111:111::42 0.0% 1 11.2 11.2 11.2 11.2 0.0 > 2.|-- ??? 100.0 1 0.0 0.0 0.0 0.0 0.0 > 3.|-- 2a0a:e5c0:2:12::7 0.0% 1 69.8 69.8 69.8 69.8 0.0 > 4.|-- 2a0a:e5c0:1:1::9 0.0% 1 74.3 74.3 74.3 74.3 0.0 > 5.|-- 2001:1620:20e6::1 0.0% 1 69.4 69.4 69.4 69.4 0.0 > 6.|-- r1zrh2.core.init7.net 0.0% 1 69.1 69.1 69.1 69.1 0.0 > 7.|-- r1olt2.core.init7.net 0.0% 1 58.0 58.0 58.0 58.0 0.0 > 8.|-- r1brn1.core.init7.net 0.0% 1 62.8 62.8 62.8 62.8 0.0 > 9.|-- r2brn1.core.init7.net 0.0% 1 65.4 65.4 65.4 65.4 0.0 > 10.|-- r1epe1.core.init7.net 0.0% 1 75.2 75.2 75.2 75.2 0.0 > 11.|-- r1qls1.core.init7.net 0.0% 1 78.4 78.4 78.4 78.4 0.0 > 12.|-- r1gva3.core.init7.net 0.0% 1 81.0 81.0 81.0 81.0 0.0 > 13.|-- gw-sunrise.init7.net 0.0% 1 64.4 64.4 64.4 64.4 0.0 > 14.|-- 2001:1700:1:7:120::2 0.0% 1 84.4 84.4 84.4 84.4 0.0 > 15.|-- 2001:1700:4d00:2::2 0.0% 1 81.3 81.3 81.3 81.3 0.0 > 16.|-- 2a00:4bc0:ffff:ff00::1d 0.0% 1 67.0 67.0 67.0 67.0 0.0 > 17.|-- ??? 100.0 1 0.0 0.0 0.0 0.0 0.0 > [10:24] line:~% mtr -w -c1 -s 1400 sbb.ch > Start: 2019-03-12T10:24:35+0100 > HOST: line Loss% Snt Last Avg Best Wrst > StDev > 1.|-- 2a0a:e5c1:111:111::42 0.0% 1 3.2 3.2 3.2 3.2 > 0.0 > 2.|-- 2a0a:e5c1:100::1 0.0% 1 69.0 69.0 69.0 69.0 > 0.0 > 3.|-- 2a0a:e5c0:2:12::7 0.0% 1 74.7 74.7 74.7 74.7 > 0.0 > 4.|-- 2a0a:e5c0:1:1::9 0.0% 1 69.9 69.9 69.9 69.9 > 0.0 > 5.|-- 2001:1620:20e6::1 0.0% 1 60.5 60.5 60.5 60.5 > 0.0 > 6.|-- r1zrh2.core.init7.net 0.0% 1 75.3 75.3 75.3 75.3 > 0.0 > 7.|-- r1olt2.core.init7.net 0.0% 1 70.7 70.7 70.7 70.7 > 0.0 > 8.|-- r1brn1.core.init7.net 0.0% 1 69.1 69.1 69.1 69.1 > 0.0 > 9.|-- r2brn1.core.init7.net 0.0% 1 54.6 54.6 54.6 54.6 > 0.0 > 10.|-- r1epe1.core.init7.net 0.0% 1 75.9 75.9 75.9 75.9 > 0.0 > 11.|-- r1qls1.core.init7.net 0.0% 1 78.8 78.8 78.8 78.8 > 0.0 > 12.|-- r1gva3.core.init7.net 0.0% 1 79.8 79.8 79.8 79.8 > 0.0 > 13.|-- gw-sunrise.init7.net 0.0% 1 69.9 69.9 69.9 69.9 > 0.0 > 14.|-- 2001:1700:1:7:120::2 0.0% 1 77.5 77.5 77.5 77.5 > 0.0 > 15.|-- 2001:1700:4d00:2::2 0.0% 1 59.3 59.3 59.3 59.3 > 0.0 > 16.|-- 2a00:4bc0:ffff:ff00::1d 0.0% 1 70.1 70.1 70.1 70.1 > 0.0 > 17.|-- ??? 100.0 1 0.0 0.0 0.0 0.0 > 0.0 > 18.|-- ??? 100.0 1 0.0 0.0 0.0 0.0 > 0.0 > 19.|-- ??? 100.0 1 0.0 0.0 0.0 0.0 > 0.0 > 20.|-- ??? 100.0 1 0.0 0.0 0.0 0.0 > 0.0 > 21.|-- ??? 100.0 1 0.0 0.0 0.0 0.0 > 0.0 > 22.|-- ??? 100.0 1 0.0 0.0 0.0 0.0 > 0.0 > 23.|-- ??? 100.0 1 0.0 0.0 0.0 0.0 > 0.0 > 24.|-- ??? 100.0 1 0.0 0.0 0.0 0.0 > 0.0 > 25.|-- 2a00:4bc0:ffff:ffff::c296:f58e 0.0% 1 58.3 58.3 58.3 58.3 > 0.0 > [10:24] line:~% > > [10:25] line:~% mtr -w -c1 -s 1420 sbb.ch > Start: 2019-03-12T10:25:44+0100 > HOST: line Loss% Snt Last Avg Best Wrst > StDev > 1.|-- 2a0a:e5c1:111:111::42 0.0% 1 16.3 16.3 16.3 16.3 > 0.0 > 2.|-- 2a0a:e5c1:100::1 0.0% 1 77.0 77.0 77.0 77.0 > 0.0 > 3.|-- 2a0a:e5c0:2:12::7 0.0% 1 67.0 67.0 67.0 67.0 > 0.0 > 4.|-- 2a0a:e5c0:1:1::9 0.0% 1 66.7 66.7 66.7 66.7 > 0.0 > 5.|-- 2001:1620:20e6::1 0.0% 1 78.8 78.8 78.8 78.8 > 0.0 > 6.|-- r1zrh2.core.init7.net 0.0% 1 64.5 64.5 64.5 64.5 > 0.0 > 7.|-- r1olt2.core.init7.net 0.0% 1 68.3 68.3 68.3 68.3 > 0.0 > 8.|-- r1brn1.core.init7.net 0.0% 1 74.9 74.9 74.9 74.9 > 0.0 > 9.|-- r2brn1.core.init7.net 0.0% 1 73.6 73.6 73.6 73.6 > 0.0 > 10.|-- r1epe1.core.init7.net 0.0% 1 62.2 62.2 62.2 62.2 > 0.0 > 11.|-- r1qls1.core.init7.net 0.0% 1 74.3 74.3 74.3 74.3 > 0.0 > 12.|-- r1gva3.core.init7.net 0.0% 1 63.6 63.6 63.6 63.6 > 0.0 > 13.|-- gw-sunrise.init7.net 0.0% 1 69.1 69.1 69.1 69.1 > 0.0 > 14.|-- 2001:1700:1:7:120::2 0.0% 1 77.4 77.4 77.4 77.4 > 0.0 > 15.|-- 2001:1700:4d00:2::2 0.0% 1 78.8 78.8 78.8 78.8 > 0.0 > 16.|-- 2a00:4bc0:ffff:ff00::1d 0.0% 1 75.7 75.7 75.7 75.7 > 0.0 > 17.|-- ??? 100.0 1 0.0 0.0 0.0 0.0 > 0.0 > 18.|-- ??? 100.0 1 0.0 0.0 0.0 0.0 > 0.0 > 19.|-- ??? 100.0 1 0.0 0.0 0.0 0.0 > 0.0 > 20.|-- ??? 100.0 1 0.0 0.0 0.0 0.0 > 0.0 > 21.|-- ??? 100.0 1 0.0 0.0 0.0 0.0 > 0.0 > 22.|-- ??? 100.0 1 0.0 0.0 0.0 0.0 > 0.0 > 23.|-- ??? 100.0 1 0.0 0.0 0.0 0.0 > 0.0 > 24.|-- ??? 100.0 1 0.0 0.0 0.0 0.0 > 0.0 > 25.|-- 2a00:4bc0:ffff:ffff::c296:f58e 0.0% 1 83.8 83.8 83.8 83.8 > 0.0 > [10:25] line:~% mtr -w -c1 -s 1430 sbb.ch > Start: 2019-03-12T10:25:55+0100 > HOST: line Loss% Snt Last Avg Best Wrst StDev > 1.|-- 2a0a:e5c1:111:111::42 0.0% 1 7.3 7.3 7.3 7.3 0.0 > 2.|-- ??? 100.0 1 0.0 0.0 0.0 0.0 0.0 > 3.|-- 2a0a:e5c0:2:12::7 0.0% 1 60.4 60.4 60.4 60.4 0.0 > 4.|-- 2a0a:e5c0:1:1::9 0.0% 1 61.9 61.9 61.9 61.9 0.0 > 5.|-- 2001:1620:20e6::1 0.0% 1 72.2 72.2 72.2 72.2 0.0 > 6.|-- r1zrh2.core.init7.net 0.0% 1 65.2 65.2 65.2 65.2 0.0 > 7.|-- r1olt2.core.init7.net 0.0% 1 64.9 64.9 64.9 64.9 0.0 > 8.|-- r1brn1.core.init7.net 0.0% 1 64.9 64.9 64.9 64.9 0.0 > 9.|-- r2brn1.core.init7.net 0.0% 1 71.7 71.7 71.7 71.7 0.0 > 10.|-- r1epe1.core.init7.net 0.0% 1 64.4 64.4 64.4 64.4 0.0 > 11.|-- r1qls1.core.init7.net 0.0% 1 63.2 63.2 63.2 63.2 0.0 > 12.|-- r1gva3.core.init7.net 0.0% 1 77.9 77.9 77.9 77.9 0.0 > 13.|-- gw-sunrise.init7.net 0.0% 1 64.5 64.5 64.5 64.5 0.0 > 14.|-- 2001:1700:1:7:120::2 0.0% 1 63.5 63.5 63.5 63.5 0.0 > 15.|-- 2001:1700:4d00:2::2 0.0% 1 81.7 81.7 81.7 81.7 0.0 > 16.|-- 2a00:4bc0:ffff:ff00::1d 0.0% 1 74.4 74.4 74.4 74.4 0.0 > 17.|-- ??? 100.0 1 0.0 0.0 0.0 0.0 0.0 > [10:26] line:~% > > > icmp6, frag works locally: > > 10:29:44.919328 IP6 2a0a:e5c1:111:111:3185:e802:6548:658c > > 2a00:4bc0:ffff:ffff::c296:f58e: frag (0|1368) ICMP6, echo request, seq 33000, > length 1368 > 10:29:44.919368 IP6 2a0a:e5c1:111:111:3185:e802:6548:658c > > 2a00:4bc0:ffff:ffff::c296:f58e: frag (1368|92) -- Your Swiss, Open Source and IPv6 Virtual Machine. 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