6in4 tunnel through ESXi is very slow

[carl9]

I have run an IPv6 tunnel on FreeBSD for about the last ten years, but over the past month or two, I've experienced slowness over IPv6 and have finally tied it to ESXi.  FreeBSD 11 with the latest patches running on ESXi 6.5 build 7967591  (Although this was an issue on previous versions too). I have tried multiple ESXi hosts and had the same result with all of them. I've tried both the Intel NIC and the VMX NIC with the same issues.If I run from a desktop running the same version of FreeBSD with the same patches, I get the speed I expect. From ESXi

Code: [Select]root@IPv6Router:/usr/home/carl # wget --no-check-certificate https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.16.2.tar.xz > /dev/null
--2018-04-17 13:23:17--  https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.16.2.tar.xz
Resolving cdn.kernel.org (cdn.kernel.org)... 2a04:4e42:2f::432, 151.101.201.176
Connecting to cdn.kernel.org (cdn.kernel.org)|2a04:4e42:2f::432|:443... connected.
WARNING: cannot verify cdn.kernel.org's certificate, issued by 'CN=GlobalSign Organization Validation CA - SHA256 - G2,O=GlobalSign nv-sa,C=BE':
  Unable to locally verify the issuer's authority.
HTTP request sent, awaiting response... 200 OK
Length: 103016908 (98M) [application/x-xz]
Saving to: 'linux-4.16.2.tar.xz.1'

linux-4.16.2.tar.xz.1                    1%[>                                                                           ]   1.39M   228KB/s    eta 6m 58s

From desktop:

Code: [Select]


$ wget --no-check-certificate https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.16.2.tar.xz > /dev/null
--2018-04-17 09:26:08--  https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.16.2.tar.xz
Resolving cdn.kernel.org (cdn.kernel.org)... 2a04:4e42:8::432, 151.101.33.176
Connecting to cdn.kernel.org (cdn.kernel.org)|2a04:4e42:8::432|:443... connected.
WARNING: cannot verify cdn.kernel.org's certificate, issued by 'CN=GlobalSign Organization Validation CA - SHA256 - G2,O=GlobalSign nv-sa,C=BE':
  Unable to locally verify the issuer's authority.
HTTP request sent, awaiting response... 200 OK
Length: 103016908 (98M) [application/x-xz]
Saving to: 'linux-4.16.2.tar.xz'

linux-4.16.2.tar.xz                 35%[=====================>                                          ]  34.56M  9.52MB/s    eta 9s 

To rule out FreeBSD, I've setup an OpenSUSE 42.3 tunnel and received the same results.

I suspect this is a VM setting somewhere, but don't have the first idea of where to look.  I've verified that the MTUs on both ends match (1480)