DieBayern2d ago
MTU in München erzielt kräftigen Gewinnsprung – Dividende steigt auf 3,60 Euro https://www.diebayern.de/wirtschaft/mtu-in-muenchen-erzielt-kraeftigen-gewinnsprung-dividende-steigt-auf-3-60-euro-3106960?utm_source=Mastodon&utm_medium=dpa&utm_content=textlink #Industrie #Deutschland #Flugzeugbau #Stahl #München #MTU #Triebwerksbauer #Gewinn #Dividende
MTU in München feiert kräftigen Gewinnsprung – Dividende klettert auf 3,60 Euro

Erfolgreiches Geschäftsjahr 2025: MTU steigert Gewinn deutlich und erhöht Dividende – Vorstand sieht starke Wachstumschancen für 2026.

DieBayern.de
Show threadAthanasiusFeb 17

FWIW I just used https://calculator-apps.com/networking-calculators/mtu-mss-calculator to calculate 'proper' MTU/MSS values for my ip(6)tables rules.

Being paranoid about TCP Timestamps and SACK that's 1420 and 1440. I've set those and will need to remember to check if I see any weird issues....

#Linux #ipv6 #mtu

Calculator Apps - MTU / MSS Calculator

Professional Network MTU/MSS calculator. Determine optimal TCP MSS size based on encapsulation overheads (PPPoE, GRE, IPsec, VXLAN) and prevent fragmentation.

AthanasiusFeb 17

Well, now I feel stupid. I finally figured out why, since upgrading to Debian 13/trixie, there are some websites I couldn't connect to, but only over IPv6, they work fine on their IPv4 address.

Fucking MTU.

I'd for a long time had an IPv4 iptables rule to force the MSS (maximum segment size) on outbound packets to `1400`. But I never put in an equivalent for IPv6.

I use 'jumbo packets' on the LAN between desktop and server, which means an MTU of 4088 (for that pair of NICs). So anything forwarded out was using an MSS of 4088 as well.

The issue only showed up for *some* sites, and only for IPv6, and only on 13/trixie because:

1. 13/trixie uses openssl 3.x, not the older version, which has slightly different cipher suites etc in the default config.
2. IPv6 addressing makes packets that little bit bigger.
3. I've only ever observed the issue with MS Azure/Edge hosts.

What was happening was that the first part of the "Server Hello" after a "Change Cipher Spec, Client Hello" from my end was being lost, as the TCP level packet was too large and fragmented... but the first fragment was too large for my PPP link.

So, added an ip6tables rule to do the set-mss thing as well, and now it works.

#Linux #IPv6 #MTU #MSS #openssl #msedge #azure

Teddy / Domingo (🇨🇵/🇬🇧)Feb 16
Différence MTU MSS : Guide complet d'optimisation #réseau. Vous êtes-vous déjà demandé pourquoi certaines #connexions réseau semblent fluides tandis que d'autres ralentissent mystérieusement ? Derrière cette différence se cache souvent un paramètre méconnu mais crucial : le #MTU (Maximum Transmission Unit)
https://networkpulse.fr/difference-mtu-mss/
Différence MTU MSS : Guide complet d'optimisation réseau

Comprenez la différence MTU MSS pour éviter la fragmentation réseau. Tutoriel complet : config, tests ping, Jumbo Frames et exemples Kubernetes.

Network Pulse
Hubu.deFeb 11
#news ⚡ MTU drängt auf europäischen Kampfjet: Der Münchner Triebwerkhersteller und Dax-Konzern MTU drängt auf eine politische Einigung für den Bau eines europäischen Kampfflugzeugs... https://hubu.de/?p=314068 | #kampfjet #mtu #hubu
MTU drängt auf europäischen Kampfjet - Hubu.de - News & FreeMail

Der Münchner Triebwerkhersteller und Dax-Konzern MTU drängt auf eine politische Einigung für den Bau eines europäischen Kampfflugzeugs und unterstützt auch den Vorschlag, zwei Jets herzustellen. "Die Zeit drängt, es muss zügig eine Entscheidung geben", sagte der MTU-Vorstandsvorsitzende Johannes Bussmann der "Süddeutschen Zeitung".

Hubu.de - News & FreeMail
Show threadadingbatponder  👾Feb 7
@eXo_X5
[Translation of above post]
Homework: Try setting the #MTU to 1270 on any interface with an #IPv6 configuration under #linux!
You will witness how all IPv6 entries simply disappear.
IPv6 is not specified for an MTU below 1280.
One could know that – I didn’t.
It would be nice if wg-quick, when calculating an MTU below 1280, would either throw a meaningful error, or set 1280 as a minimum if IPv6 is configured.
Better occasional #fragmentation than no IPv6 at all.
5/6
Show threadadingbatponder  👾Feb 7
@eXo_X5
[Translation of above post]
I have to admit that at this point I asked ChatGPT, and it actually gave the correct answer.
wg-quick doesn’t just bring the interface up, it also sets an appropriate MTU to prevent fragmentation.
But the #Bahn has configured its wifi network so strangely that the wifi interface itself only has an #MTU of 1350.
If you now subtract the 80 bytes of #WireGuard overhead, the WG interface is left with only 1270 bytes MTU.
4/6
Reddit Tech VN BotJan 4

IP Fragmentation: ảnh hưởng tới hiệu suất mạng hiện đại như thế nào và trong môi trường có tự động phát hiện MTU, nó còn cần thiết không? #IPFragmentation #Mạng #CôngNghệ #Networking #IP #MTU #SelfHosted

https://www.reddit.com/r/selfhosted/comments/1q3rgbi/ip_fragmentation/

John GoerzenNov 17

I have gigabit fiber (up and down) out in rural #Kansas. I remain very thankful for the end to decades of dealing with weird antennas and such.

But today they switched from raw #Ethernet to #PPPoE, and although performance hasn't suffered to a noticeable extent, my #MTU has gone from 1500 to 1492. I am probably irrationally annoyed at this.

But dammit, PPP? In 2025? And going backwards on packet size?

S I G H.

Jody Lemoine 🇨🇦Nov 10
There’s always another 🕳️ to go down. Now it’s a packet-level analysis of raw L2TPv3 pseudowires vs UDP encapsulated ones to find out •why• the raw ones come in with a lower automatic MTU than the UDP ones do. On the surface, this makes no sense. #NetEng #Labbing #L2TP #MTU #TunnelsAllTheWayDown