[Bug 262292] Seemingly not possible for IPv6 to function over tap devices on if_bridge
Date: Fri, 14 Nov 2025 02:41:41 UTC
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=262292
--- Comment #11 from Brad Ackerman <brad@facefault.org> ---
(In reply to ivy from comment #10)
So the problem is that I'm not quite figuring out how to share a /64 with the
jails. I've got a /64 from which I'd like to assign both jails and the host; if
I remove the address from the host's external interface NDP on the bridge
starts working — but telling ifconfig that the prefixlen is 128 on all the
global-scope addresses (and then setting up a far gateway on the jail) doesn't
seem to make a difference.
jails: flags=1008843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST,LOWER_UP> metric 0
mtu 1500
options=0
ether 58:9c:fc:10:80:39
inet 172.21.188.1 netmask 0xfffffc00 broadcast 172.21.191.255
inet6 fe80::5a9c:fcff:fe10:8039%jails prefixlen 64 scopeid 0x4
inet6 2604:2dc0:200:2116::ff:ffff prefixlen 64
id 00:00:00:00:00:00 priority 32768 hellotime 2 fwddelay 15
maxage 20 holdcnt 6 proto rstp maxaddr 2000 timeout 1200
root id 00:00:00:00:00:00 priority 32768 ifcost 0 port 0
member: e0a_powerdns flags=143<LEARNING,DISCOVER,AUTOEDGE,AUTOPTP>
ifmaxaddr 0 port 8 priority 128 path cost 2000
groups: bridge
nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
e0a_powerdns:
flags=1008943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST,LOWER_UP> metric 0
mtu 1500
description: vnet0 host interface for Bastille jail powerdns
options=8<VLAN_MTU>
ether 02:57:e9:cd:fc:0a
groups: epair
media: Ethernet 10Gbase-T (10Gbase-T <full-duplex>)
status: active
nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
Inside jail, the other side of the epair:
vnet0: flags=1008843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST,LOWER_UP> metric 0
mtu 1500
options=8<VLAN_MTU>
ether 02:57:e9:cd:fc:0b
inet6 2604:2dc0:200:2116::4 prefixlen 64
inet6 fe80::57:e9ff:fecd:fc0b%vnet0 prefixlen 64 scopeid 0x9
groups: epair
media: Ethernet 10Gbase-T (10Gbase-T <full-duplex>)
status: active
nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
$ sudo tcpdump -nvvve -i jails
tcpdump: listening on jails, link-type EN10MB (Ethernet), snapshot length
262144 bytes
02:13:07.789039 02:cb:b3:d7:b8:0b > 33:33:ff:ff:ff:ff, ethertype IPv6 (0x86dd),
length 86: (hlim 255, next-header ICMPv6 (58) payload length: 32)
2604:2dc0:200:2116::4 > ff02::1:ffff:ffff: [icmp6 sum ok] ICMP6, neighbor
solicitation, length 32, who has 2604:2d
c0:200:2116::ff:ffff
source link-address option (1), length 8 (1): 02:cb:b3:d7:b8:0b
0x0000: 02cb b3d7 b80b
02:13:08.789166
02:cb:b3:d7:b8:0b > 33:33:ff:ff:ff:ff, ethertype IPv6 (0x86dd), length 86:
(hlim 255, next-header ICMPv6 (58) payload length: 32) 2604:2dc0:200:2116::4 >
ff02::1:ffff:ffff: [icmp6 sum ok] ICMP6, neighbor solicitation, length 32, who
has 2604:2d
c0:200:2116::ff:ffff
source link-address
option (1), length 8 (1): 02:cb:b3:d7:b8:0b
0x0000: 02cb b3d7 b80b
02:13:09.816291 02:cb:b3:d7:b8:0b > 33:33:ff:ff:ff:ff, ethertype IPv6 (0x86dd),
length 86: (hlim 255, next-header ICMPv6 (58) payl
oad length: 32) 2604:2dc0:200:2116::4 > ff02::1:ffff:ffff: [icmp6 sum ok]
ICMP6, neighbor solicitation, length 32, who has 2604:2dc0:200:2116::ff:ffff
source link-address option (1), length 8
(1): 02:cb:b3:d7:b8:0b
0x0000: 02cb b3d7 b80b
02:13:15.163167
02:cb:b3:d7:b8:0b > 33:33:ff:ff:ff:ff, ethertype IPv6 (0x86dd), length 86:
(hlim 255, next-header ICMPv6 (58) payload length: 32) 2604:2dc0:200:2116::4 >
ff02::1:ffff:ffff: [icmp6 sum ok] ICMP6, neighbor solicitation, length 32, who
has 2604:2d
c0:200:2116::ff:ffff
source link-address
option (1), length 8 (1): 02:cb:b3:d7:b8:0b
0x0000: 02cb b3d7 b80b
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