Patch is merged now. Thanks, -Matt
On Thu, Mar 5, 2026 at 7:31 PM Matthew Smith via lists.fd.io <mgsmith= [email protected]> wrote: > > Hi Pim, > > There were some changes around tap creation which likely caused the issue > - > https://github.com/FDio/vpp/commit/cb19c526dd1c907569a00936c35e8c1b663008dd#diff-f7f8eb1b374b1dd5000dcb44b237615f6bb8c5d29aa022a92356161f6bb96e60L1073. > Prior to that, hw was being set to point to the tap interface. > > When the CI verify jobs finish and give your gerrit the +1, I'll merge it. > > Thanks, > -Matt > > > > On Thu, Mar 5, 2026 at 6:56 PM Pim van Pelt via lists.fd.io <pim= > [email protected]> wrote: > >> Hoi folks, >> >> I was playing around with af-packet and creating LCP pairs with them. >> I noticed a bunch of errors with 'l3 mac mismatch' while multicast >> worked, unicast did not. >> >> I saw commits 1412d24ba and 3e00a101be but they are innocent, rolling >> them back in my build would not fix the situation. >> >> I realized that linux-cp has a bug in lcp_interface.c: >> - After tap_create_if() on L1064, hw still points to the PHY's HW >> interface from L841. >> - The STATUS_L3 flag ends up on the PHY (in my case the AF_PACKET >> interface), not on tapXXXX. Linux sends unicast with the peer's real >> MAC, which mismatches the tap's synthetic 02:fe:... mac address and thus >> gets dropped. Multicast is allowed to bypass DMAC checks, and thus >> multicast works. >> >> The fix seems simple - look up a new hw from the args.sw_if_index (the >> TAP) and set the flag on that one. Considering how long we've had Linux >> CP and no changes around the TAP creation that I could see, am I perhaps >> misreading this? >> >> https://gerrit.fd.io/r/c/vpp/+/45103 is a fix. Without it, containerlab >> created eth1/eth2/ethN af-packet interfaces, but the corresponding >> tap4096/tap4097/tap4098 were not in promiscuous mode. With the gerrit, >> containerlab works and the TAPs are in promiscuous mode. >> >> Please take a look. >> >> >> >> -- >> Pim van Pelt <[email protected]> >> PBVP1-RIPE https://ipng.ch/ >> >> >> >> >> > > >
-=-=-=-=-=-=-=-=-=-=-=- Links: You receive all messages sent to this group. View/Reply Online (#26870): https://lists.fd.io/g/vpp-dev/message/26870 Mute This Topic: https://lists.fd.io/mt/118163322/21656 Group Owner: [email protected] Unsubscribe: https://lists.fd.io/g/vpp-dev/leave/14379924/21656/631435203/xyzzy [[email protected]] -=-=-=-=-=-=-=-=-=-=-=-
