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I noticed there's a certain page taking a long time (5 to 10s) to load on Firefox. I traced the delay and it happens when trying to connect to a certain host, bn.uol.com.br.

Strangely, this delay only happens on Firefox, but not on Chrome / Chromium. It happens on Firefox 31.0 on Ubuntu 14.04, happens on Firefox 42.0 on Windows 10, and happens on Firefox 42.0.1 on Android 4.4.4; but it doesn't happen on Chromium 45.0.2454.101 for Ubuntu 14.04, or Chrome 46.0.2490.86m for Windows 10 or Chrome 34.0.1847.114 for Android 4.4.4.

I want to end this delay on all OS'es and all devices, either by properly enabling IPv6, or by entirely disabling it.

I had previously noticed intermittent apt-get stalling on random IPv6 addresses. I suspect (but I'm not certain) my ISP doesn't enable IPv6, and I also suspect (but also not sure) IPv6 is disabled on my wireless AP/router. I got suspicious and performed the http://test-ipv6.com/ test on both browsers on all OS's (same wireless network, same router / AP).

Here's the results:

Firefox on Ubuntu

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Chromium on Ubuntu

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Firefox on Android

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Chrome on Android

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Firefox on Win10

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Chrome on Win10

enter image description here

Additional tests


wget (Win 10)

enter image description here

There's a long pause before the IPv6 timeout.

More testes on a vanilla live USB Ubuntu

$ wget bn.uol.com.br
--2015-11-30 22:11:29--  http://bn.uol.com.br/
Resolving bn.uol.com.br (bn.uol.com.br)... 200.147.35.201, 2804:49c:319:430::126
Connecting to bn.uol.com.br (bn.uol.com.br)|200.147.35.201|:80... failed: Connection refused.
Connecting to bn.uol.com.br (bn.uol.com.br)|2804:49c:319:430::126|:80... [5s PAUSE HERE] failed: No route to host.

There's a long pause before the above IPv6 timeout.

$ ping6 bn.uol.com.br
PING bn.uol.com.br(2804:49c:319:430::126) 56 data bytes
From fe80::3e77:e6ff:XXXX:XXXX icmp_seq=1 Destination unreachable: Address unreachable
From fe80::3e77:e6ff:XXXX:XXXX icmp_seq=2 Destination unreachable: Address unreachable
From fe80::3e77:e6ff:XXXX:XXXX icmp_seq=3 Destination unreachable: Address unreachable
^C
--- bn.uol.com.br ping statistics ---
6 packets transmitted, 0 received, +3 errors, 100% packet loss, time 5009ms

$ ip -6 addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
3: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000
    inet6 fe80::3e77:e6ff:XXXX:XXXX/64 scope link 
       valid_lft forever preferred_lft forever

$ ip -6 route
fe80::/64 dev wlan0  proto kernel  metric 256 
default dev wlan0  proto kernel  metric 256  expires 86397sec
default via fe80::9e97:26ff:XXXX:XXXX dev wlan0  proto ra  metric 1024  expires 297sec

The third line seems to point to my wifi ap/router, although I'd suppose IPv6 is disabled on it (it's a Technicolor TD5130v2 and the user interface is quite confusing)

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  • Could you post ip -6 addr and ip -6 route on Linux (preferably), or netsh interface ipv6 show addr & netsh interface ipv6 show route on Windows? Dec 1, 2015 at 6:05
  • @grawity I added the response of those commands. Dec 4, 2015 at 1:37
  • Hmm, so your router still advertises IPv6 accessibility via itself (the "default … proto ra" line), even though it doesn't have any addresses to offer. Is it a D-Link? Although I'm also kinda curious where the other "default … proto kernel" route comes from; it's a weird one. Dec 4, 2015 at 6:53
  • It's a Technicolor TD5130v2. The control panel is a bit confusing and I know nothing about IPv6 Dec 4, 2015 at 17:24

1 Answer 1

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You do not have an IPv6 address, most likely because your ISP did not make the transition to IPv6 yet, like most ISPs in the world.

Your address fe80::3e77:e6ff:feb4:41a1 is a link-local address,see here for intance:

A link-local address is an IPv6 unicast address that can be automatically configured on any interface using the link-local prefix FE80::/10 (1111 1110 10)

Besides, the reply from http://test-ipv6.com/ is identical to mine from home, where I surely do not have an IPv6 connection.

Edit

In reply to grawity's comment, I tried ping6-ing from one of my vps'es:

root@vps:~# ping6 -c3 bn.uol.com.br
PING bn.uol.com.br(2804:49c:319:FEED::FEEB) 56 data bytes

--- bn.uol.com.br ping statistics ---
3 packets transmitted, 0 received, 100% packet loss, time 2001ms

It tries to connect, it has an IPv6-capable DNS, no reply, because I do not have an IPv6 connection on this vps. Ubuntu, which is used in the OP, like surely all Debian's but at this point I suspect all Linuxes, is perfectly capable of self-configuring IPv6, if a non-link-local-address is found.

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  • That's only part of the problem though. If the network really was without IPv6, then the connection wouldn't even be attempted at all due to no default ::/0 route. (I get an instant 0/10 after disabling IPv6.) Dec 1, 2015 at 9:07
  • @grawity Wrote an Edit meant for you, could you tell me whether you agree? Thanks. Dec 1, 2015 at 9:16
  • That depends on what ip -6 route your VPS has. Dec 1, 2015 at 9:37

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