[ovs-discuss] OVC port MTU 1500 dhcp-options mtu 9000

Brendan Doyle brendan.doyle at oracle.com
Thu Nov 19 10:53:20 UTC 2020


Folks,

I'm trying to get OVN working in a 9000 MTU config so :

  ovn-nbctl list dhcp-option
_uuid               : 00f684c8-42bb-4fad-a248-f5697926778d
cidr                : "10.225.1.0/24"
external_ids        : {}
options             : {lease_time="3600", mtu="9000", 
router="10.225.1.1", server_id="10.225.1.1", server_mac="00:13:97:60:de:6a"}

The hypervisor phys interface MTU is 9000, so I know the above should 
specify MTU of 8950 to account
for the geneve header, in any case I manually lower the MTU on the VM 
node but things still don't work.
And I think the reason is that when I looked at the OVS br-int, I see 
the OVN port MTU is 1500. How
do I get OVN to create the br-int port with a 9000/8950 MTU?

Is this something we have to manually configure on the OVS bridge?

ovs-vsctl list interface vnet1
_uuid               : 49637687-3870-4eea-911a-e22c6c2ef19a
admin_state         : up
bfd                 : {}
bfd_status          : {}
cfm_fault           : []
cfm_fault_status    : []
cfm_flap_count      : []
cfm_health          : []
cfm_mpid            : []
cfm_remote_mpids    : []
cfm_remote_opstate  : []
duplex              : full
error               : []
external_ids        : {attached-mac="00:13:97:32:18:d6", 
iface-id="dc5bca80-2948-11eb-96a2-0010e0c3df92", iface-status=active, 
vm-id="11b14a04-59ed-45e9-9445-665b8847fba7"}
ifindex             : 26
ingress_policing_burst: 0
ingress_policing_rate: 0
lacp_current        : []
link_resets         : 1
link_speed          : 10000000
link_state          : up
lldp                : {}
mac                 : []
mac_in_use          : "fe:13:97:32:18:d6"
mtu                 : 1500
mtu_request         : []
name                : "vnet1"
ofport              : 13
ofport_request      : []
options             : {}
other_config        : {}
statistics          : {collisions=0, rx_bytes=88983, rx_crc_err=0, 
rx_dropped=0, rx_errors=0, rx_frame_err=0, rx_over_err=0, 
rx_packets=470, tx_bytes=33425, tx_dropped=0, tx_errors=0, tx_packets=279}
status              : {driver_name=tun, driver_version="1.6", 
firmware_version=""}
type                : ""


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