IPv6 Deployment for ISPs: MikroTik Configuration & Transition Planning

Why ISPs Need IPv6 Now

IPv4 addresses are exhausted in most regions. ISPs are forced to use CGNAT, which breaks peer-to-peer applications, gaming, VoIP, and remote access. IPv6 gives every subscriber a globally routable address space — no NAT, no port mapping, no workarounds.

Major content providers (Google, Netflix, Facebook, Cloudfront) serve IPv6 natively. Subscribers with IPv6 get a faster, more direct path to these services.

IPv6 Address Planning for ISPs

ISPs typically receive a /32 or /29 IPv6 allocation from their RIR. Here is how to break it down:

With a /32 allocation, you have 65,536 /48 blocks. Even at /56-per-subscriber, that is over 16 million subscribers — more than enough for any ISP.

Enabling IPv6 on MikroTik

Start by enabling the IPv6 package and configuring addresses:

# Enable IPv6
/system package enable ipv6
# (reboot required after enabling)

# Add IPv6 address to WAN interface
/ipv6 address
add address=2001:db8:1::1/64 interface=ether1-wan advertise=no

# Add IPv6 address to LAN (for subscriber-facing interface)
/ipv6 address
add address=2001:db8:100::1/64 interface=bridge-lan advertise=yes

# Default route to upstream
/ipv6 route
add dst-address=::/0 gateway=2001:db8:1::ffff

DHCPv6 Prefix Delegation for Subscribers

Prefix Delegation (PD) is the standard way to assign IPv6 subnets to subscribers. Each subscriber gets a /56 or /60 that their CPE router can further subnet for their LAN.

# Create IPv6 pool for prefix delegation
/ipv6 pool
add name=subscriber-pd-pool prefix=2001:db8:100::/40 prefix-length=56

# DHCPv6 server with prefix delegation
/ipv6 dhcp-server
add name=dhcpv6-subscribers interface=bridge-lan     address-pool=subscriber-pd-pool lease-time=3d

Dual-Stack PPPoE with IPv6

For PPPoE deployments, enable IPv6 on the PPP profile so subscribers get both IPv4 and IPv6 addresses:

# Add IPv6 pool for PPPoE subscribers
/ipv6 pool
add name=pppoe-v6-pool prefix=2001:db8:200::/40 prefix-length=56

# Update PPP profile to include IPv6
/ppp profile
set 10Mbps dhcpv6-pd-pool=pppoe-v6-pool use-ipv6=yes
set 25Mbps dhcpv6-pd-pool=pppoe-v6-pool use-ipv6=yes
set 50Mbps dhcpv6-pd-pool=pppoe-v6-pool use-ipv6=yes

This is a dual-stack approach — subscribers receive both IPv4 and IPv6. Their traffic uses whichever protocol the destination supports, with Happy Eyeballs algorithm preferring IPv6 when available.

IPv6 Firewall Rules

Do not forget to configure IPv6 firewall rules. The IPv6 firewall is separate from IPv4:

/ipv6 firewall filter
add chain=input action=accept connection-state=established,related
add chain=input action=drop connection-state=invalid
add chain=input action=accept protocol=icmpv6 comment="Accept all ICMPv6"
add chain=input action=accept protocol=udp dst-port=546     comment="Accept DHCPv6 replies"
add chain=input action=accept src-address-list=management     comment="Management access"
add chain=input action=drop comment="Drop all other input"

add chain=forward action=accept connection-state=established,related
add chain=forward action=drop connection-state=invalid
add chain=forward action=accept protocol=icmpv6
add chain=forward action=accept comment="Accept forwarded traffic"

ICMPv6 is essential for IPv6 operation (Neighbor Discovery, Path MTU Discovery). Never block all ICMPv6 or IPv6 will break.

How ISPbills Supports IPv6

ISPbills is fully IPv6-ready:

• Dual-stack subscriber management — track both IPv4 and IPv6 address assignments per subscriber
• RADIUS IPv6 attributes — manage Framed-IPv6-Prefix and Delegated-IPv6-Prefix attributes
• IPv6 traffic monitoring — NetFlow/SNMP monitoring works with both IPv4 and IPv6 traffic
• Gradual migration — manage mixed IPv4-only, dual-stack, and IPv6-only subscribers in the same system