You can do it without a reboot:
[22.09-DEVELOPMENT][root@2100-2.stevew.lan]/root: ifconfig mvneta0
mvneta0: flags=8a43<UP,BROADCAST,RUNNING,ALLMULTI,SIMPLEX,MULTICAST> metric 0 mtu 1500
description: WAN
options=800bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,LINKSTATE>
ether 00:e0:ed:b6:13:59
inet6 fe80::2e0:edff:feb6:1359%mvneta0 prefixlen 64 scopeid 0x1
inet 172.21.16.220 netmask 0xffffff00 broadcast 172.21.16.255
media: Ethernet autoselect (1000baseSX <full-duplex>)
status: active
nd6 options=23<PERFORMNUD,ACCEPT_RTADV,AUTO_LINKLOCAL>
[22.09-DEVELOPMENT][root@2100-2.stevew.lan]/root: ifconfig mvneta0
mvneta0: flags=8a43<UP,BROADCAST,RUNNING,ALLMULTI,SIMPLEX,MULTICAST> metric 0 mtu 1500
description: WAN
options=800bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,LINKSTATE>
ether 00:e0:ed:b6:13:59
inet6 fe80::2e0:edff:feb6:1359%mvneta0 prefixlen 64 scopeid 0x1
inet 172.21.16.220 netmask 0xffffff00 broadcast 172.21.16.255
media: Ethernet autoselect (none)
status: no carrier
nd6 options=23<PERFORMNUD,ACCEPT_RTADV,AUTO_LINKLOCAL>
[22.09-DEVELOPMENT][root@2100-2.stevew.lan]/root: ifconfig mvneta0
mvneta0: flags=8a43<UP,BROADCAST,RUNNING,ALLMULTI,SIMPLEX,MULTICAST> metric 0 mtu 1500
description: WAN
options=800bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,LINKSTATE>
ether 00:e0:ed:b6:13:59
inet6 fe80::2e0:edff:feb6:1359%mvneta0 prefixlen 64 scopeid 0x1
media: Ethernet autoselect (1000baseT <full-duplex>)
status: active
nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
[22.09-DEVELOPMENT][root@2100-2.stevew.lan]/root: ifconfig mvneta0
mvneta0: flags=8a43<UP,BROADCAST,RUNNING,ALLMULTI,SIMPLEX,MULTICAST> metric 0 mtu 1500
description: WAN
options=800bb<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,LINKSTATE>
ether 00:e0:ed:b6:13:59
inet6 fe80::2e0:edff:feb6:1359%mvneta0 prefixlen 64 scopeid 0x1
inet 172.21.16.220 netmask 0xffffff00 broadcast 172.21.16.255
media: Ethernet autoselect (1000baseT <full-duplex>)
status: active
nd6 options=23<PERFORMNUD,ACCEPT_RTADV,AUTO_LINKLOCAL>
Steve