em0: No buffer space available for IPv6 traffic but IPv4 is OK
Date: Fri, 18 Aug 2023 08:01:41 UTC
Hi, on this intel em0 # dmesg |fgrep em0 em0: <Intel(R) Gigabit CT 82574L> port 0xd800-0xd81f mem 0xfe9e0000-0xfe9fffff,0xfe9dc000-0xfe9dffff irq 48 at device 0.0 on pci1 em0: Using 1024 TX descriptors and 1024 RX descriptors em0: Using 2 RX queues 2 TX queues em0: Using MSI-X interrupts with 3 vectors em0: Ethernet address: xx:xx:xx:xx:xx:xx em0: netmap queues/slots: TX 2/1024, RX 2/1024 IPv4 and IPv6 used to work seamlessly for the past 6+ years. # ifconfig em0 em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 options=81249b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,LRO,WOL_MAGIC,VLAN_HWFILTER> ether xx:xx:xx:xx:xx:xx inet xxx.xxx.xxx.xxx netmask 0xffffff00 broadcast xxx.xxx.xxx.255 inet6 fe80::xxxx:xxxx:xxxx:xxxx%em0 prefixlen 64 scopeid 0x1 inet6 2xxx:xxxx:xxxx:xxxx::1 prefixlen 64 media: Ethernet autoselect (100baseTX <full-duplex>) status: active nd6 options=23<PERFORMNUD,ACCEPT_RTADV,AUTO_LINKLOCAL> Nevertheless, now IPv6 traffic does not work anymore: # ping6 www.google.com PING6(56=40+8+8 bytes) 2xxx:xxxx:xxxx:xxxx::1 --> 2yyy:yyyy:yyyy:yyyy::1 ping6: sendmsg: No buffer space available ping6: wrote www.google.com 16 chars, ret=-1 From send(2): [...] [ENOBUFS] The system was unable to allocate an internal buffer. The operation may succeed when buffers become available. [ENOBUFS] The output queue for a network interface was full. This generally indicates that the interface has stopped sending, but may be caused by transient congestion. [...] There is little traffic on the interface and it seems that buffers are available: # netstat -m 2108/3472/5580 mbufs in use (current/cache/total) 2062/1336/3398/1018874 mbuf clusters in use (current/cache/total/max) 15/1250 mbuf+clusters out of packet secondary zone in use (current/cache) [...] Interestingly, there is incoming IPv6 local broadcast traffic as sniffed by # tcpdump -n -i em0 ip6 (ICMP6, neighbor solicitation, UDP from LAN link local addresses). Has anyone seen this before and can suggest a fix? Reboot did not solve, no software updates made, no config changes, just stop working from one day to the next. Thank you. -- José Pérez