Hello,

I currently own an RB2011UiAS-2HnD router which i use on my 500/500 fiber connection.
On IPv4 with FastTrack i get great performance with this little router and am able to fully utilize the available bandwidth. On IPv6 however i see that the Mikrotik hits 100% CPU, which i did not expect since the router no longer has to do NAT.

IPv4 Performance:

IPv6 Performance: My ISP offerts two VLANS, of which one VLAN is for internet the other is for IPTV. On the internet VLAN an PPPoE connection is setup with a MTU of 1492 and (afaik) no encryption. On this VLAN i receive a IPv6 prefix directly via the DHCPv6 client. All clients on my network have an IPv6 adres that starts with this prefix. I do not have any firewall rules in the IPv6 firewall just yet, so that is not causing the high cpu. Does anybody has a indication where i should look? I am currently running RouterOS 6.38rc52. When i run the profiler i can see most CPU is used by the firewall, while there are no firewall rules: Any help is greatly appreciated!

The router no longer has to do NAT, but it also probably can't do FastPath/FastTrack with IPv6, those features help to speed up IPv4.

I see in the benchmarks that this router can only do about 250Mbps in real world thoughput, so what you are getting is fine with IPv6. You are probably getting the boost in IPv4 from fastpath or fasttrack.

I currently own an RB2011UiAS-2HnD router which i use on my 500/500 fiber connection.

That is stretching the limits of this router... when you want to really use this connection to the max I suggest getting a CCR or at least a faster RB (3011, 750Gr3)

My ISP offerts two VLANS, of which one VLAN is for internet the other is for IPTV. On the internet VLAN an PPPoE connection is setup with a MTU of 1492 and (afaik) no encryption. On this VLAN i receive a IPv6 prefix directly via the DHCPv6 client

When this is XS4ALL, you don't need to limit the MTU to 1492 but you can set the PPPoE MRU/MTU/MRRU to 1500 and the MTU on ether1 to 1512 or so.
Then you avoid some issues because of the nonstandard MTU.

That is stretching the limits of this router... when you want to really use this connection to the max I suggest getting a CCR or at least a faster RB (3011, 750Gr3)

I know, but maybe something like fasttrack was also in the making for IPv6.
I think i will consider upgrading to a RB3011, too bad it is only available as rack mount.

Thank you for the replies

CCR1009 is available as standalone, and RB750G r3 is only a very small box.
Of course they have fewer ports and no WiFi. But you can use a RB750G r3 as your router and continue to use the switches
of the 2011 with a single bridge to combine the 10 ethernet ports and the WiFi. This will give you gigabit performance on the
first 5 ports and reasonable performance on ports 6-10 and the WiFi. RB750G r3 is very cheap (much less than a 3011).