[CentOS] Disable DHCPv6 on Cent7

So, I'm seeing a bunch of DHCPv6 traffic coming from my CentOS7
machines. Basically, the machines are trying to send router
solicitations, the packets are blocked at their egress firewalls, and
I get to see the logs.

I don't wish to disable IPv6. I don't wish to statically configure
IPv6 at this time. I wish to have the machines no longer attempting to
send router solicitations as part of DHCPv6.

How do I do this? I tried

DHCPV6C="no"

in ifcfg-ifacethatsnoteth0, but that seems to have had no effect. I
still see lines like these:

Feb 25 10:25:48 proxy-comcast-2 NetworkManager[541]: <error>
[1424877948.384918] [rdisc/nm-lndp-rdisc.c:241] send_rs(): ([snip]):
cannot send router solicitation: -1.
Feb 25 10:25:48 proxy-comcast-2 kernel: OUT-world:IN= OUT=[snip]
SRC=fe80:[snip] DST=ff02:0000:0000:0000:0000:0000:0000:0002 LEN=48
TC=0 HOPLIMIT=255 FLOWLBL=0 PROTO=ICMPv6 TYPE=133 CODE=0

-- 
:wq