HE IPv6 Tunnel experiences very high latency

Issues related to configuring your network
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rdk
Posts: 2
Joined: 2018/01/08 18:30:32

HE IPv6 Tunnel experiences very high latency

Postby rdk » 2018/01/08 18:51:40

Hi!

Hey, I recently switched ISPs from Charter to AT&T for fiber and gigabit speeds -- pretty sweet. I built a new PC/CentOS7 router for
my new configuration. Its taken a while to get everything moved and re-configured but everything is working now with respect to IPv4.

My HE IPv6 tunnel is also now working but its really really dog slow and thus all IPv6 traffic is dog slow.

I can ping ICMPv4 to the HE IPv4 tunnel endpoint and get 30ms round-trip time.

I can IPv4 traceroute to the HE IPv4 tunnel endpoint setting proto=41 and I get 38 ms round trip time. Proto 41 is what IPv6-in-IPv4 tunnel packets traverse with.

That leads me to believe that AT&T is not slowing my tunnel traffic nor blocking/filtering it.

HE has replied to my questions saying that nothing is wrong with their tunnel server and that they can ping IPv4 my systems with low latency.

However, when I turn on the tunnel, ping6 to the HE side take a whopping 750ms! Traceroute and ping to other IPv6 addresses takes
similar amount of time. And, turning on IPv6 tunnel also causes IPv4 jitter and I see spikes with IPv4 pings times as well. Weird.

The only real architectural different between my old setup and new setup is that my old setup with Charter had a global IPv4 address on
my external interface in addition to my globally routable block on an internal subnet.

In my AT&T configuration, my router's external interface is a non-routable subnet between me and my modem. My block of global routable IPv4 addresses are on a subnet on one of my internal interfaces. Thus my IPv4 side of my HE tunnel is an internal interface with a globally routable IPv4 address. Don't know if this is relevant.

Also, one other difference is that my new router uses an Intel chip based quad-port ethernet card. (Intel Corporation 82580 Gigabit)

Any ideas or suggestions as to what is causing a 750ms delay over IPv6? I've ran wireshark and wireshark also sees a 750ms delay
between icmp6 echo and responses.

Neither google nor logs show anything interesting.

I don't believe the latency is caused by iptables as when I temporarily turn off ipv4 and ipv6 iptables, I don't see any improvement.

Thanks,

Bobby

User avatar
rdk
Posts: 2
Joined: 2018/01/08 18:30:32

Re: HE IPv6 Tunnel experiences very high latency

Postby rdk » 2018/01/08 22:00:56

Hi!

I should add that my tunnel worked fine with very low latency when I used my old FC17 router with my charter service. I had latency times in the 30-35ms range.

However, switching to a new PC/CentOS7 router and to AT&T has somehow resulted in a 750ms RTT with ping6 to my HE tunnel endpoint.

Stumped.

Bobby