Effect of fragmentation in QOS

[shivlu jain]

If the packets are fragmented in ingress and QOS is used, Does the QOS will be maintained after fragmentation. Like in GRE we have QOS pre classify to preserve the bits.

regards

shivlu jain

[amit.bhagat]

Hi Shivlu,

During every fragmentation, the IP header is preserved. So if a packet is fragmented, first the header is preserved, the payload is fragmented and the original IP header is applied to all fragmented packets. This way you will still keep the IP Precedence or DSCP values in the IP header.

This is true for GRE too.

However, packet fragmentation can spike up your router processor.

Link efficiency can be improved using Link Fragmentation Interleaving (LFI) by reducing serialization delay.

HTH.

Amit.

[shivlu jain]

Hi Amit

Thanks for your reply. But we have tested by sending packet more than 1500 bytes and after fragmentation some packets are marked with QOS bits but some are not.

regards

shivlu jain