NSX-T tier-1 router's uplink?

[niceguy001]

I just read the NFV openstack document and there is a figure I couldn't interpret for myself:

I'm wandering about how the tier-1 routers can be connected to the N-VDS instead of the tier-0 router?

In my opinion the tier-1 router's uplink should always connect to tier-0 router therefore an inter-tier connection of subnet 100.64.0.0/10 is created by default.

so the question is, why can the tier-1 router be connected to N-VDS directly as shown in figure above?

B.T.W. another question is: can VMs utilize physical switch's VLAN network by connecting to nsx-t logical switches(traffic type set to VLAN) just like connecting to vSwitch portgroups?

[SRoland · Accepted solution]

Hi,

I'm wandering about how the tier-1 routers can be connected to the N-VDS instead of the tier-0 router?

In my opinion the tier-1 router's uplink should always connect to tier-0 router therefore an inter-tier connection of subnet 100.64.0.0/10 is created by default.

so the question is, why can the tier-1 router be connected to N-VDS directly as shown in figure above?

You are right they are directly connected, but at the end of the day T1 gateways are connected through an N-VDS (i.e. a VNI) to the T0-s. Just this connection is not presented to the user directly.

If you get into an Edge node (ssh/console) just execute the "get-logical routers"; select a T1 DR; get its UUID and run "get logical-router <UUID> interfaces". You should see a line showing "VNI: XXXX" for each connection.

I am not sure though why they presented this in such way. This creates the confusion like you just asked. Maybe they wanted to emphasize the N-VCD / vDS "domain separation" in some ways.

B.T.W. another question is: can VMs utilize physical switch's VLAN network by connecting to nsx-t logical switches(traffic type set to VLAN) just like connecting to vSwitch portgroups?

I don't see why not. That would be the only option if you use only N-VDS on a hypervisor. Just be aware that the hosts/hypervisors must be added to the VLAN transport zone and have at least one physical interface available on the given N-VDS for them..

//Roland