We get improvement in default values compared with vSphere 5.1 but there are still default values which you need to change directly after host installation
MTU is set by default to 1500 have to be changed to 1600
VMware recommends for VXLAN setting physical and virtual switch MTU to 1600, rather than the default of 1500. This takes into account a guest standard MTU of 1514 bytes and optional 802.1PQ tag of four bytes, giving the the guest an ethernet frame of 1518 bytes. A port group provisioned with a standard or distributed switch that uses VLAN adds another four bytes, bringing the ethernet frame to 1522 bytes.
SA, DA, eth_type 0x0800: 14 bytes
IPv4 header: 20 bytes
UDP header: 8 bytes
VDL2 header: 8 bytes
VDL2 IPv4 encapsulated frame: 1522 bytes + 14 bytes + 20 bytes + 8 bytes + 8 bytes = 1572 bytes
Increasing the maximum number of ports designated for an ESXi 5.5 host
Standard switch default is 120 ports
Imagine you have 3 hosts and 250 VMs, this configuration will run good, but what in case of host failure?
You will have 2 host and 250 VMs, in case of HA you have 240 ports available and 10 VMs will be without network.
Distributed switch default is 256 port – this could be ok, but you need to calculate to be sure.
Default configuration allows for only eight NFS mounts per ESXi host.
NFS.MaxVolumes: Limits the number of NFS datastores which can be mounted by the vSphere ESXi/ESX host concurrently. The default value need to be increased as well with other parameters see details in KB article.