Thank you for replies everyone.
There appears to be significant differences between the trunk configuration and behaviour on the SG500 and SG550X. From your queries:
Switchport VLAN Settings:
SG500 cannot set the native vlan on the member ports of the LAG.
SG500(config)#int gi1/8
SG500(config-if)#switch trunk native vlan 500
Port gi1/8 belongs to a port-channel.
SG550X:
interface GigabitEthernet1/0/1
channel-group 2 mode auto
switchport mode trunk
switchport trunk native vlan 500
!
interface GigabitEthernet1/0/2
channel-group 2 mode auto
switchport mode trunk
switchport trunk native vlan 500
!
Port-Channel VLAN Settings:
When configuring the SG500 and specifying "switch trunk allowed vlan add x" it uses an inclusive method in the config.
interface Port-channel1
spanning-tree link-type point-to-point
switchport trunk allowed vlan add 70-71
switchport trunk native vlan 500
no macro auto smartport
You cannot include the native VLAN in the allowed vlans on the SG500. If i used the command:
switch trunk allowed vlan add 500
Then the SG500 removes the "switch trunk native vlan 500" and changes the port-channel to native vlan 1.
On the SG550X the config uses an exclusion method for the allowed vlans in the config when creating.
interface Port-Channel2
spanning-tree link-type point-to-point
switchport mode trunk
switchport trunk native vlan 500
switchport trunk allowed vlan remove 1-69,72-499,501-4094
no macro auto smartport
SG550X has the opposite native VLAN behaviour, if the native vlan specified is not included in the allowed vlans then the VLAN interface will not come up with the port.
Channel-Group modes
Channel groups modes supported are only ON or AUTO on both SG500 and SG550X.
SG500(config)#int gi1/8
SG500(config-if)#channel-group 4 mode
on Add port without LACP
auto Add port with LACP
Mode on appears to exhibit the same behaviour, I am using auto as this enables LACP which is desirable to detect link issues and remove the channel member affected.
Working Config
To get this working I had to do the following:
- On SG500
- LAG member interfaces switch mode trunk.
- LAG member interfaces channel-group mode "auto".
- Port-channel native vlan 500.
- Port-channel allowed vlans 70,71
- On SG550x
- LAG member interfaces switch mode trunk.
- LAG member interfaces switch trunk native vlan 500.
- LAG member interfaces channel-group mode "auto".
- Port-Channel native vlan 500.
- Port-Channel allowed vlans 70,71,500.
Working config:
SG500:
interface gigabitethernet1/25
channel-group 1 mode auto
!
interface gigabitethernet1/26
channel-group 1 mode auto
!
interface Port-channel1
spanning-tree link-type point-to-point
switchport trunk allowed vlan add 70-71
switchport trunk native vlan 500
no macro auto smartport
SG550X:
interface TengigabitEthernet1/0/1
channel-group 1 mode auto
switchport mode trunk
switchport trunk native vlan 500
!
interface TengigabitEthernet1/0/2
channel-group 1 mode auto
switchport mode trunk
switchport trunk native vlan 500
!
interface Port-Channel1
spanning-tree link-type point-to-point
switchport mode trunk
switchport trunk native vlan 500
switchport trunk allowed vlan remove 1-69,72-499,501-4094
no macro auto smartport
This just seems to be a very odd difference in behaviour, the SG500 behaves more as I would expect in not needing the native VLAN to be in the allowed vlans, but the SG550X behaves more as I would expect in mirroring the same trunk settings on the memeber interfaces.
I know the SMB switches don't behave in exactly the same way as the catalyst enterprise switches but this is just a bit bizarre.
