Manual:IPv6 Overview
- Packages required: ipv6
- Software versions: 3.0beta10+
IPv6 overview
Internet Protocol version 6 (IPv6) is the new version of the Internet Protocol (IP). It was initially expected to replace IPv4 in short enough time, but for now it seems that these two version will coexist in Internet in foreseeable future. Nevertheless, IPv6 becomes more important, as the date of unallocated IPv4 address pool's exhaustion approaches.
The two main benefits of IPv6 over IPv4 are:
- much larger address space (IPv6 uses 16 bytes addresses compared to 4 byte addresses in IPv4);
- support of stateless address autoconfiguration.
Supported programms
MikroTik IPv6 support at the moment (RouterOS 3.28/4.0beta4):
- static addressing and routing;
- router advertisement daemon (for address autoconfiguration)
- dynamic routing: BGP+, OSPFv3, and RIPng protocols
- DNS name servers;
- 6in4 (SIT) tunnels;
- telnet;
- ping;
- traceroute;
- web proxy;
- sniffer and fetch tools;
Features not yet supported:
- DHCPv6;
- all PPP (Point-to-point protocols);
- IPSEC;
- SSH, FTP, API, Winbox, Webbox access;
- queues;
- automatic tunnel creation;
- policy routing;
- multicast routing;
- MPLS;
- torch, netwatch, bandwidth test and other tools;
IP addressing
IPv6 uses 16 bytes addresses compared to 4 byte addresses in IPv4.
There are multiple IPv6 address classes. RouterOS distinguishes the following:
- multicast (with prefix ff00::/8)
- link-local (with prefix fe80::/10)
- loopback (the address ::1/128)
- unspecified (the address ::/128)
- other (all other addresses, including the obsoleted site-local addresses and RFC 4193 unique local addresses; they all are treated as global unicast).
Basic IPv6 address configuration example:
ipv6 address add address=fc00:1::1/64 interface=ether1 ipv6 address add address=fc00:2::1/64 interface=ether2
One difference between IPv6 and IPv4 addressing is that IPv6 automatically generates a link-local IPv6 address for each active interface that has IPv6 support.
Example:
[admin@MikroTik] > ipv6 address print Flags: X - disabled, I - invalid, D - dynamic, G - global, L - link-local # ADDRESS INTERFACE ADVERTISE 0 DL fe80::20c:42ff:fe1d:3d3/64 ether2 no 1 DL fe80::20c:42ff:fe1d:3d2/64 ether1 no 2 DL fe80::20c:42ff:fe1d:3d4/64 ether3 no 3 G fc00:1::1/64 ether1 yes 4 G fc00:2::1/64 ether2 yes
For IPv6 automatically generated addresses are also often used. Such addresses consist of two parts:
- 64 bit long network prefix (usually manually configured for routers, and received via RADVD for host);
- 64 bit long unique identifier.
The 64 bit unique ID is generated from hardware serial numbers or MAC addresses. In case of a 48 bit MAC address, the so called EUI-64 (Extended Unique Identifier) is generated by this algorithm:
- use the first 3 bytes of the MAC address (OUI) as the first 3 bytes of the EUI-64, except that the second-least significant bit of the most significant byte is inverted;
- insert 0xFF and 0xFE as 4th and 5th bytes of the EUI-64 respectively;
- use the last 3 bytes of the MAC address as the last 3 bytes of the EUI-64;
(Image)
In RouterOS, if the eui-64 parameter for an address is configured, the 64 bits of that address will be automatically generated and updated using interface's MAC address. These last bits must be configured as zero for this case. Example:
[admin@MikroTik] > ipv6 address add address=fc00:3::/64 interface=ether3 eui-64=yes [admin@MikroTik] > ipv6 address print Flags: X - disabled, I - invalid, D - dynamic, G - global, L - link-local # ADDRESS INTERFACE ADVERTISE ... 5 G fc00:3::20c:42ff:fe1d:3d4/64 ether3 yes [admin@MikroTik] > interface ethernet set ether3mac-address=10:00:00:00:00:01 [admin@MikroTik] > ipv6 address print Flags: X - disabled, I - invalid, D - dynamic, G - global, L - link-local # ADDRESS INTERFACE ADVERTISE ... 5 G fc00:3::1200:ff:fe00:1/64 ether3 yes
If the advertise=yes configuration option is set for an IPv6 address, the prefix of that address is automatically advertised to hosts using ICMPv6 protocol. The option is set by default for addresses with prefix length 64. Note that the prefix length must be equal to 64 for host autoconfiguration to work. /ipv6 nd prefixes print console command shows information about prefixes that are currently advertised:
[admin@MikroTik] > ipv6 nd prefix print
Flags: X - disabled, I - invalid, D - dynamic
0 D prefix=fc00:1::/64 interface=ether1 on-link=yes autoconfig=yes
valid-lifetime=4w2d preferred-lifetime=1w
External resources: http://www.tcpipguide.com/free/t_IPv6Addressing.htm
IP routing
For static routing, the basic principles of IPv6 are exactly the same as for IPv4. Example:
[admin@MikroTik] > ipv6 route add dst-address=2001::/16 gateway=fc00:1::2
[admin@MikroTik] > ipv6 route print detail
Flags: X - disabled, A - active, D - dynamic,
C - connect, S - static, r - rip, o - ospf, b - bgp, U - unreachable
0 A S dst-address=2001::/16 gateway=fc00:1::2 reachable ether1 distance=1
scope=30 target-scope=10
Perhaps the most notable difference is that link local addresses can be used as route nexthops only if interface is specified too. Example:
[admin@MikroTik] > ipv6 route add dst-address=2002::/16 gateway=fe80::21a:4dff:fe56:1f4d%ether1
[admin@MikroTik] > ipv6 route print detail
Flags: X - disabled, A - active, D - dynamic,
C - connect, S - static, r - rip, o - ospf, b - bgp, U - unreachable
...
1 A S dst-address=2002::/16
gateway=fe80::21a:4dff:fe56:1f4d%ether1 reachable distance=1
scope=30 target-scope=10
Another small difference is that there are no "blackhole" or "prohibit" routes, only "unreachable".
IPv4 and IPv6 routing also differs in the area of multipath route. Technically speaking, in Linux kernel there is no support for multiple nexthops for a IPv6 route. However, RouterOS allows to set more than one gateway address for a single route. In this case, a route is installed in the kernel for each of the different interfaces to which route's nexthops belong.
Example:
[admin@MikroTik] > ipv6 address p
Flags: X - disabled, I - invalid, D - dynamic, G - global, L - link-local
# ADDRESS INTERFACE ADVERTISE
0 G fc00:1::1/64 ether1 no
1 G fc00:2::1/64 ether2 no
[admin@MikroTik] > ipv6 route add dst-address=2001::/16 gateway=fc00:1::2,fc00:2::2
[admin@MikroTik] > ipv6 route print
Flags: X - disabled, A - active, D - dynamic,
C - connect, S - static, r - rip, o - ospf, b - bgp, U - unreachable
# DST-ADDRESS GATEWAY DISTANCE
0 A S 2001::/16 fc00:2::2 reachable ether1, 1
fc00:1::2 reachable ether2
When printing the Linux kernel route table, we see that two routes were added, not one:
# ip -6 route 2001::/16 via fc00:2::2 dev eth1 proto static metric 1024 mtu 1500 advmss 1440 metric10 4294967295 2001::/16 via fc00:1::2 dev eth0 proto static metric 1024 mtu 1500 advmss 1440 metric10 4294967295 ...
Dynamic routing protocols
BGP
Because of it's design BGP naturally supports multiple address families, and migration to IPv6 is straightforward here.
Example: configure iBGP between routers A and B, AS 65000, that will exchange IPv4 and IPv6 routes.
Router A:
[admin@A] > routing bgp peer add remote-address=10.0.0.134 remote-as=65000 address-families=ip,ipv6
Router B:
[admin@B] > routing bgp peer add remote-address=10.0.0.133 remote-as=65000 address-families=ip,ipv6
Redistribute a route from router A to router B:
[admin@A] > ipv6 route add dst-address=2001::/16 gateway=fe80::1%ether1 [admin@A] > routing bgp network add network=2001::/16 [admin@A] > routing bgp advertisements print PEER PREFIX NEXTHOP AS-PATH ORIGIN LOCAL-PREF peer1 2001::/16 fe80::1200:ff... igp 100
[admin@B] > ipv6 route print Flags: X - disabled, A - active, D - dynamic, C - connect, S - static, r - rip, o - ospf, b - bgp, U - unreachable # DST-ADDRESS GATEWAY DISTANCE 0 ADb 2001::/16 fe80::1200:ff:fe00:10... 200
IPv6 addresses can also be used in peer configuration in remote-address and update-source fields - to make a BGP connection over IPv6.
OSPF
Unlike to BGP, adding IPv6 support to OSPF required a lot of changes and resulted in a new, incompatible, version of OSPF: protocol version 3. (For IPv4, OSPF version 2 is used). The new version is described in RFC 2740.
OSPFv3 uses the same fundamental mechanisms as OSPFv2 — LSAs, flooding, the SPF algorithm, etc. However, it add not only support to a new address family, but also some improvements to the protocol itself. It avoid some potential problems and inefficiencies present in the operation of OSPFv2.
OSPFv3 configuration syntax largely remains the same as for OSPFv2. One mayor difference is that there is no configuration for networks anymore, and interface configuration becomes mandatory, since OSPFv3, runs on link, not IP subnet, basis.
Example:
Configure OSPF on router A:
[admin@A] > routing ospf-v3 interface add interface=ether1 area=backbone
Configure OSPF on router B:
[admin@B] > routing ospf-v3 interface add interface=ether1 area=backbone
Redistribute a route from router A to router B:
[admin@A] > ipv6 route add dst-address=2001::/16 gateway=fe80::1%ether1 [admin@A] > routing ospf-v3 instance set default redistribute-static=as-type-1 [admin@A] > routing ospf-v3 route print # DESTINATION STATE COST 0 2001::/16 imported-ext-1 20
[admin@B] > ipv6 route print Flags: X - disabled, A - active, D - dynamic, C - connect, S - static, r - rip, o - ospf, b - bgp, U - unreachable # DST-ADDRESS GATEWAY DISTANCE 0 ADo 2001::/16 fe80::1200:ff:fe00:10... 110
RIP
Similarly to OSPF, a new version of RIP was required to add IPv6 support. The new version is called RIPng (RIP new generation) and described in RFC 2080. Just like OSPFv3, RIPng runs on link, not IP subnet, basis - this means that you need to configure interfaces, not IP networks, on which to run RIPng.
Example:
Configure RIP on router A:
[admin@A] > routing ripng interface add interface=ether1
Configure RIP on router B:
[admin@B] > routing ripng interface add interface=ether1
Redistribute a route from router A to router B:
[admin@A] > ipv6 route add dst-address=2001::/16 gateway=fe80::1%ether1 [admin@A] > routing ripng set redistribute-static=yes [admin@A] > routing ripng route print Flags: C - connect, S - static, R - rip, O - ospf, B - bgp # DST-ADDRESS 0 S 2001::/16
[admin@B] > ipv6 route print Flags: X - disabled, A - active, D - dynamic, C - connect, S - static, r - rip, o - ospf, b - bgp, U - unreachable # DST-ADDRESS GATEWAY DISTANCE 0 ADr 2001::/16 fe80::1200:ff:fe00:10... 120
Stateless autoconfiguration
RouterOS has stateless IPv6 address autoconfiguration support using Router Advertisement Daemon (RADVD). Prefixes of all addresses with 64 bit netmask are advertised by default. Example:
[admin@MikroTik] /ipv6 nd prefix> /ipv6 address p
Flags: X - disabled, I - invalid, D - dynamic, G - global, L - link-local
# ADDRESS INTERFACE ADVERTISE
0 G fc00:1::1/64 ether1 yes
[admin@MikroTik] > ipv6 nd prefix print
Flags: X - disabled, I - invalid, D - dynamic
0 D prefix=fc00:1::/64 interface=ether1 on-link=yes autoconfig=yes
valid-lifetime=4w2d preferred-lifetime=1w
On a host that is directly attached to the router:
atis@atis-desktop:~$ ip -6 addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000
inet6 fc00:1::21a:4dff:fe56:1f4d/64 scope global dynamic
valid_lft 2588363sec preferred_lft 601163sec
inet6 fe80::21a:4dff:fe56:1f4d/64 scope link
valid_lft forever preferred_lft forever
The host has received the fc00:1::/64 prefix from the router and configure an address with it.
There is also an option to redistribute DNS server information using RADVD:
[admin@MikroTik] > ip dns set secondary-dns=fc00:1::2
[admin@MikroTik] > ip dns print
primary-dns: 10.0.0.1
secondary-dns: fc00:1::2
...
[admin@MikroTik] > ipv6 nd set [f] advertise-dns=yes
You will need a running client side software with Router Advertisement DNS support to take advantage of the advertised DNS information.
6to4 tunnels
This describes solution using global 6to4 relay address. For a solution using a tunnel broker see Setting up an IPv6 tunnel via a tunnel broker.
First, you need a global routable IPv4 address. We assume the address 1.2.3.4 for the sake of this example.
Then you need to make user that the global 6to4 relay anycast address 192.88.99.1 is reachable and that it really provides relay services (since it's anycast address, your connection should be routed to the host having this addresses that is the closest to your location).
interface 6to4 add mtu=1280 local-address=1.2.3.4 disabled=no
Now you need to add a IPv6 address to the tunnel interface. The address should be in form "2002 + <IPv4 address in hex> + <custom id>". A bash script can be used to generated sch address to generate IPv6 address for you:
atis@atis-desktop:~$ ipv4="1.2.3.4"; id="1"; printf "2002:%02x%02x:%02x%02x::$id\n" `echo $ipv4 | tr "." " "` 2002:0102:0304::1
Add the generated address to the 6to4 interface:
ipv6 address add address=2002:0102:0304::1/128 interface=sit1
Add route to global IPv6 Internet through the tunnel interface using the anycast IPv4 address:
ipv6 route add dst-address=2000::/3 gateway=::192.88.99.1,sit1
Syntax for routing-test:
ipv6 route add dst-address=2000::/3 gateway=::192.88.99.1%sit1
Now try to ping some IPv6 host (e.g. ipv6.google.com) to check your IPv6 connectivity.
See also 6to4 in Wikipedia. Do not confuse 6to4 tunnels with 6in4 or 6over4 - similarly named, but different mechanisms!
Using dual stack
All IP services that listen to IPv6 also accept IPv4 connections. We take the web proxy for an example.
To force the web proxy to listen to IPv6 connections:
/ip proxy set src-address=::
To demonstrate that the dual stack is working, we connect to the web proxy at 10.0.0.131/fc00:1::1 using telnet, issue "GET /" request, and observe generated error message.
Connecting via IPv4:
$ telnet 10.0.0.131 8080 Trying 10.0.0.131... Connected to 10.0.0.131. Escape character is '^]'. GET /
HTTP/1.0 404 Not Found Content-Length: 518 ... Generated Mon, 18 Dec 2006 12:40:03 GMT by 10.0.0.131 (Mikrotik HttpProxy)
Connecting via IPv6:
$ telnet -6 fc00:1::1 8080 Trying fc00:1::1... Connected to fc00:1::1. GET /
HTTP/1.0 404 Not Found Content-Length: 525 ... Generated Mon, 18 Dec 2006 12:38:51 GMT by ::ffff:10.0.0.131 (Mikrotik HttpProxy)