Date: Fri, 19 Apr 2019 21:11:27 +0200 From: Marco van Tol <marco@tols.org> To: "Andrey V. Elsukov" <bu7cher@yandex.ru> Cc: Marco van Tol <marco@tols.org>, freebsd-net@freebsd.org Subject: Re: unicast vxlan - unable to tcp connect to ipv6 ip's on endpoint host Message-ID: <57CC19F7-5914-4FA0-A689-626229C774AA@tols.org> In-Reply-To: <0ae5cb32-684c-99ca-cca0-88cce2f8a2fb@yandex.ru> References: <B6BC7B2F-7864-427D-ABF0-8E635206F40F@tols.org> <0ae5cb32-684c-99ca-cca0-88cce2f8a2fb@yandex.ru>
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Op 19 apr. 2019, om 14:53 heeft Andrey V. Elsukov <bu7cher@yandex.ru> = het volgende geschreven: >=20 > On 19.04.2019 13:46, Marco van Tol wrote: >> There is one exception to this: Host B can ping Host A on any of its >> IPv6 addresses, but it cannot make any tcp connection to any of the >> IPv6 addresses on Host A. Is this expected? >=20 > Hi, >=20 > this looks like the problem with checksum offloading. When such > offloading is enabled on the interface, such protocols like TCP and = UDP > defer checksum calculation to interface hardware. ICMPv6 does checksum > calculation in software, thus it usually does not affected by such > problem. Sometimes NIC hardware or driver have bugs and offloading = does > not work correctly. You can try to disable checksum offloading on your > interfaces and then try. Also you can use tcpdump to try determine = what > the problem you have with TCP. Ha! Thank you very much, this fixed it. In my case the physical interface used on Host A for = transmitting/receiving the vxlan packets was an if_bce interface. After I did the following on host A, Host B could make an IPv6 tcp = connection on for example port 443 of host A. ifconfig bce0 -rxcsum Many thanks! --=20 Marco van Tol
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