Performance with ipv6 only connection - no more NAT

Installing and Using OpenWrt
1

I am just wondering if anyone knows about performance for ipv6 only connection.

  1. With ipv6 there is no need for NAT anymore. Can we expect gigabit performance even on a old router hardware from ~2011? If qualcomm fast path patch can enable old router hardware to achieve gigabit speed with nat, we can expect gigabit speed without nat on ipv6, right? I will do a iperf test sometimes this week with an old router using ar9344 and see how fast it can get over wan <-> lan without NAT by simply bridging the interface together.

  2. Are there overheads in ipv6 compared to ipv4 that would negate the performance benefit from not having to do nat?

2

I took a look at the ipv6 spec.

Regarding performance, key points:

  1. Processing is greatly reduced in the IP layer. IPv6 doesn't do (to name a few) fragmentation, nat, checksum and offload/remove these processing to the end clients. So router cpu performance should have much less impact on throughput.
  2. The packet header for ipv6 is much larger than that of ipv4. This means the application layer data rate may be reduced because of the increased overhead in data format lleading to overall throughput decrease if you transport packets over the same medium with same PHY rate assuming unlimited hardware processing speed.

I will do a test sometimes this week with

  1. ipv4 across bridged wan-lan without nat
  2. ipv6 across wan-lan

and see how it performs. Not sure how to force ipv6 for 2) yet though.

3

I did some benchmark - quite surprising result. I am pretty sure I did something wrong.

The test was done with a ar9344 platform (dir 835). This cpu is rather old which is exactly what I needed to measure the ipv6 no nat performance.

Result:

both lan, ipv4

Server listening on 5201

Accepted connection from 192.168.5.227, port 49800
[ 5] local 192.168.5.203 port 5201 connected to 192.168.5.227 port 49801
[ ID] Interval Transfer Bandwidth
[ 5] 0.00-1.00 sec 106 MBytes 892 Mbits/sec
[ 5] 1.00-2.00 sec 112 MBytes 942 Mbits/sec
[ 5] 2.00-3.00 sec 112 MBytes 942 Mbits/sec
[ 5] 3.00-4.00 sec 112 MBytes 942 Mbits/sec
[ 5] 4.00-5.00 sec 112 MBytes 942 Mbits/sec
[ 5] 5.00-6.00 sec 112 MBytes 942 Mbits/sec
[ 5] 6.00-7.00 sec 112 MBytes 942 Mbits/sec
[ 5] 7.00-8.00 sec 112 MBytes 942 Mbits/sec
[ 5] 8.00-9.00 sec 112 MBytes 942 Mbits/sec
[ 5] 9.00-10.00 sec 112 MBytes 942 Mbits/sec
[ 5] 10.00-10.05 sec 6.05 MBytes 937 Mbits/sec

both lan, ipv6

Accepted connection from fe80::4d5:5a31:4769:eb39, port 49834
[ 5] local fe80::3d70:2aa5:2ab7:3a92 port 5201 connected to fe80::4d5:5a31:4769:eb39 port 49835
[ ID] Interval Transfer Bandwidth
[ 5] 0.00-1.00 sec 105 MBytes 881 Mbits/sec
[ 5] 1.00-2.00 sec 111 MBytes 929 Mbits/sec
[ 5] 2.00-3.00 sec 111 MBytes 929 Mbits/sec
[ 5] 3.00-4.00 sec 111 MBytes 929 Mbits/sec
[ 5] 4.00-5.00 sec 111 MBytes 929 Mbits/sec
[ 5] 5.00-6.00 sec 111 MBytes 929 Mbits/sec
[ 5] 6.00-7.00 sec 111 MBytes 929 Mbits/sec
[ 5] 7.00-8.00 sec 111 MBytes 929 Mbits/sec
[ 5] 8.00-9.00 sec 111 MBytes 929 Mbits/sec
[ 5] 9.00-10.00 sec 111 MBytes 929 Mbits/sec
[ 5] 10.00-10.05 sec 5.69 MBytes 930 Mbits/sec

[ ID] Interval Transfer Bandwidth
[ 5] 0.00-10.05 sec 0.00 Bytes 0.00 bits/sec sender
[ 5] 0.00-10.05 sec 1.08 GBytes 924 Mbits/sec receiver

wan lan bridged, ipv4 (full sirq)

Accepted connection from 192.168.5.227, port 49849
[ 5] local 192.168.5.203 port 5201 connected to 192.168.5.227 port 49850
[ ID] Interval Transfer Bandwidth
[ 5] 0.00-1.00 sec 103 MBytes 866 Mbits/sec
[ 5] 1.00-2.00 sec 112 MBytes 941 Mbits/sec
[ 5] 2.00-3.00 sec 105 MBytes 879 Mbits/sec
[ 5] 3.00-4.00 sec 109 MBytes 917 Mbits/sec
[ 5] 4.00-5.00 sec 109 MBytes 912 Mbits/sec
[ 5] 5.00-6.00 sec 112 MBytes 942 Mbits/sec
[ 5] 6.00-7.00 sec 108 MBytes 908 Mbits/sec
[ 5] 7.00-8.00 sec 92.8 MBytes 778 Mbits/sec
[ 5] 8.00-9.00 sec 89.7 MBytes 753 Mbits/sec
[ 5] 9.00-10.00 sec 112 MBytes 942 Mbits/sec
[ 5] 10.00-10.05 sec 5.47 MBytes 939 Mbits/sec

wan lan bridged, ipv6 (full sirq)

Accepted connection from fe80::4d5:5a31:4769:eb39, port 49843
[ 5] local fe80::3d70:2aa5:2ab7:3a92 port 5201 connected to fe80::4d5:5a31:4769:eb39 port 49844
[ ID] Interval Transfer Bandwidth
[ 5] 0.00-1.00 sec 104 MBytes 873 Mbits/sec
[ 5] 1.00-2.00 sec 111 MBytes 928 Mbits/sec
[ 5] 2.00-3.00 sec 110 MBytes 920 Mbits/sec
[ 5] 3.00-4.00 sec 111 MBytes 928 Mbits/sec
[ 5] 4.00-5.00 sec 110 MBytes 922 Mbits/sec
[ 5] 5.00-6.00 sec 110 MBytes 924 Mbits/sec
[ 5] 6.00-7.00 sec 110 MBytes 921 Mbits/sec
[ 5] 7.00-8.00 sec 111 MBytes 928 Mbits/sec
[ 5] 8.00-9.00 sec 110 MBytes 921 Mbits/sec
[ 5] 9.00-10.00 sec 109 MBytes 918 Mbits/sec
[ 5] 10.00-10.05 sec 5.49 MBytes 924 Mbits/sec

nat, ipv4 (full sirq)

[ 4] local 192.168.5.203 port 62774 connected to 192.168.2.2 port 5201
[ ID] Interval Transfer Bandwidth
[ 4] 0.00-1.00 sec 24.5 MBytes 205 Mbits/sec
[ 4] 1.00-2.00 sec 24.2 MBytes 203 Mbits/sec
[ 4] 2.00-3.00 sec 24.6 MBytes 207 Mbits/sec
[ 4] 3.00-4.00 sec 24.4 MBytes 204 Mbits/sec
[ 4] 4.00-5.00 sec 24.5 MBytes 205 Mbits/sec
[ 4] 5.00-6.00 sec 22.2 MBytes 187 Mbits/sec
[ 4] 6.00-7.00 sec 23.2 MBytes 195 Mbits/sec
[ 4] 7.00-8.00 sec 22.6 MBytes 190 Mbits/sec
[ 4] 8.00-9.00 sec 23.0 MBytes 193 Mbits/sec
[ 4] 9.00-10.00 sec 22.4 MBytes 188 Mbits/sec

[ ID] Interval Transfer Bandwidth
[ 4] 0.00-10.00 sec 236 MBytes 198 Mbits/sec sender
[ 4] 0.00-10.00 sec 236 MBytes 198 Mbits/sec receiver

ipv6 wan - lan (full sirq)

Accepted connection from 2001:db80::1, port 49928
[ 5] local 2001:db80:1::3a92 port 5201 connected to 2001:db80::1 port 49929
[ ID] Interval Transfer Bandwidth
[ 5] 0.00-1.00 sec 26.0 MBytes 218 Mbits/sec
[ 5] 1.00-2.00 sec 27.5 MBytes 230 Mbits/sec
[ 5] 2.00-3.00 sec 27.6 MBytes 232 Mbits/sec
[ 5] 3.00-4.00 sec 27.4 MBytes 230 Mbits/sec
[ 5] 4.00-5.00 sec 27.6 MBytes 231 Mbits/sec
[ 5] 5.00-6.00 sec 27.4 MBytes 230 Mbits/sec
[ 5] 6.00-7.00 sec 27.6 MBytes 231 Mbits/sec
[ 5] 7.00-8.00 sec 27.3 MBytes 229 Mbits/sec
[ 5] 8.00-9.00 sec 27.5 MBytes 231 Mbits/sec
[ 5] 9.00-10.00 sec 27.3 MBytes 229 Mbits/sec
[ 5] 10.00-10.06 sec 1.78 MBytes 232 Mbits/sec

..What? I want to highlight the result for "ipv6 wan - lan" and "wan lan bridged, ipv6 (full sirq)"

There's no NAT going on in "ipv6 wan - lan (full sirq)" - how is it different from "wan lan bridged, ipv6 (full sirq)"? Ideally one should be able to achieve bridge like performance across wan lan as the ipv6 over bridged wan-lan shows that the hardware is capable of doing so. What is the networking stack doing extra in "ipv6 wan - lan (full sirq)" that causes its performance to equal that of ipv4 where there are more processing needed?

*I did "ipv6 wan - lan (full sirq)" test both with and without firewall, but it did not have much impact in the iperf result.

4

i would have expected the main cost to be connection-tracking (even w/o nat).

how did you "disable firewall"
were sqm-scripts enabled?