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How to test and fix IPv6 fragmentation issues

In an earlier blog post, I discussed the issues associated with IPv6 packet fragmentation. Of particular significance, IPv6 fragmentation relies extensively on the computer sourcing packets being able to receive ICMPv6 “packet too big” message type 2 sent from any intermediate device in the route to the packet’s destination.

The capability to confirm that an end user in a network will correctly receive the packet-too-big ICMPv6 message has been added to the test-ipv6 mirrors, including http://test-ipv6.arbor.net. This new capability allows a user to identify if the packet-too-big message is being discarded between the user’s computer and the web site.

In the “Tests Run” tab of the main test-ipv6 mirror page, the “Test IPv6 large packet” test documents the IPv6 fragmentation behavior. If further information is desired, one can click on the “Technical Info” link.

If the “Test IPv6 large packet” test is failing, the packet-too-big ICMPv6 message is likely being dropped. This indicates issues within the user’s computer, enterprise network or elsewhere along the path to the test-ipv6 mirror.  The problematic device may be a router or firewall device, although it may even be the “firewall” software configured on the user’s computer.

Any device in the Continue reading

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How to test and fix IPv6 fragmentation issues

In an earlier blog post, I discussed the issues associated with IPv6 packet fragmentation. Of particular significance, IPv6 fragmentation relies extensively on the computer sourcing packets being able to receive ICMPv6 “packet too big” message type 2 sent from any intermediate device in the route to the packet’s destination. The capability to confirm that an […]