On Mon, 6 Apr 2020 at 13:12, Mark Tinka <mark.tinka@seacom.mu> wrote:
https://github.com/FRRouting/frr/blob/58980443821edf95719984e01f31720bd1dc7f...
But as long as you don't pad, your PDU shouldn't exceed 1500B.
Good man, you gave me an idea.
There are other interesting implications about this high MTU commit - https://github.com/FRRouting/frr/commit/316a98ecd151dfba86a4a87e11c98cb2a0e9... If in FRR you generate large LSP (many interfaces or prefixes), FRR may actually generate as large LSP as MTU allows. This means it doesn't interoperate between Cisco and Juniper, which will fragment generated LSPs at 1492B, no matter what CLSN MTU you have. On Cisco you can increase LSP MTU to 4352, on Juniper you cannot increase above 1492B. So FRR should have an addition of LSP-MTU which should default to 1492B to avoid interoperability issues when it must generate large LSP PDU. So better not make config where FRR needs to inject larger LSP PDU, might be more excitement than what people would like. Someone can test what happens when you redistribute more prefixes than can fit in 1492B LSP PDU and if those LSPs propagate to Ciscos and Juniper, blackhole or crash the network. -- ++ytti