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[#120368533] Add set_mtu job #2
Story: Reduce MTU of VMs to 1500
We have discovered an MTU related problem with AWS's nat-gateway service which is causing us all sorts of problems at the moment, including:
The MTU is different for different machine sizes on AWS, but a lot of the larger ones (which we're using) now default to using Jumbo frames, with MTU 9001. AWS doesn't give us enough control over the dhcp-option-sets to set the MTU for ourselves.
The problem doesn't happen if you spin up your own nat-masquerading linux box. AWS has confirmed they see the problem when we sent them some code to try out MTU sizes from 1513 to 517 bytes. They say the've worked out a fix and will deploy it by 30th June
The bosh-agent seems to overwrite the dhclient.conf when it starts up. But we can use a bosh addon to write a DHCP hook to set the MTU whenever the lease is renewed.
How to review
Review with MTU PR on paas-cf
Once this is merged, update MTU on paas-cf to point to merge commit id
Who can review
Anyone but @jimconner or me
Could you add a brief description to the PR about the previous SPIKE: