Fragmentation

GigaVUE-VM allows fragment of packets leaving the tunnel. Fragmentation can be enabled or disabled per tunnel. Fragmentation is needed if the tunneled packet size plus the tunnel header size is greater than the tunnel MTU size. If fragmentation is not specified in this situation, the tunneled packet is dropped. IP fragment reassembly occurs at the H Series nodes starting with GigaVUE‑OS 4.6. For versions lower than version GigaVUE‑OS 4.6, it is suggested that fragmentation be disabled on the GigaVUE-VM.

Support for fragmentation is as follows:

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Fragmentation is only supported for IPv4 packets.

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Fragmentation and reassembly is not supported on ERSPAN tunnels.

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Packets encapsulated with a GRE header on G-vTAP Agents do not undergo fragmentation in the current release.

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GigaVUE-VM does not reassemble GRE packets received from the G-vTAP Agent.

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Filtering on fragmented packets is from layer 2 to layer 3 because only the first fragment will have the transport header. In the current release, GigaVUE-VM does not support filtering on fragments for layer 4.

In VMware environments, packets can be dropped when the packet frame length is greater than the GigaVUE-VM tunnel MTU after adding the tunnel header. In this case, the packets are fragmented and sent out of the tunnel interface. However, it is not guaranteed that the packet will reach the GigaVUE H Series because intermediate devices may not support fragmentation.