VLAN to VXLAN translation in ACI

[ciscoaci2015]

Hi ACI Guru's

Could you please clarify the following?

If i have 2 endpoints in same VLAN (example VLAN:10), in same EPG (eg EPG: XYZ). Endpoint one is connected to Leaf1 and endpoint 2 is connected to Leaf2. 

for the above scenario, does corresponding VXLAN's for VLAN:10 has to match on both leaf switches ?

or can we have, (VLAN=10) == (VXLAN=100) on leaf1 and (VLAN=10) == (VXLAN=200) on Leaf2 ?

Regards,

Riki

[Jason Williams]

Riki, 

The VXLAN to VLAN mapping is automatically provisioned by ACI. Typically VXLANs are IDs for bridge domains and Encap VLANs are mapped to EPGs. VXLANs can be EPGs if using AVS in VXLAN mode. 

ACI uses multiple types of VLANs since it goes through a VLAN translation process. 

Encap VLAN - User configured VLAN which is shown in EPG static binding or VMM integration. This VLAN remains consistent across all leaves. 

Platform Independent (PI) VLAN - This VLAN is commonly seen when executing switch show commands. They map to Encap VLANs and VXLANs. PI VLAN IDs are not consistent across all leaves. 

See example below for example of VLAN ID consistency:

I have configured VLAN 1901 on an EPG and want to track what platform independent VLAN it maps to on a my leaves. 

Leaf1# show vlan extended | grep vlan-1901
49 enet CE vlan-1901

According to Leaf1, Encap VLAN 1901 maps to PI VLAN 49

Leaf2# show vlan extended | grep vlan-1901
37 enet CE vlan-1901

According to Leaf2, Encap VLAN is still 1901 but it maps to PI VLAN 37

When running other show commands show as show ip interface brief or show interface eth x/y switchport, the VLANs shown are the PI VLANs. Use the show vlan extended to show the VLAN mapping.

Jason

[ciscoaci2015]

Hi Jason, 

Could you please explain what is the use of Encap, PI, BD and FD VLANs in the fabric. 

Regards,

Riki

[ciscoaci2015]

Hi Guys,

can someone else please explain what is the difference and use of Encap, PI, BD and FD VLANs in the fabric. 

Regards,

Riki

[sitaram91]

@ciscoaci2015 This seems to be very old post and you might be an ace in ACI by now but just commenting here for reference for others as your last comment is still unanswered.

Encap VLAN- This is nothing but on-the-wire VLAN in traditional switching environment. You define it on EPG/Access port on ACI from where traffic will enter into fabric.

PI VLAN- Platform Independent VLAN is nothing but an internal VLAN ACI maps on a specific node like leaf switch. This can map be mapped to encap VLAN or VXLAN or BD SVI ID.

BD VLAN- This is nothing but mapping for the specific bridge domain in ACI. This is useful to determine if traffic needs to be switched locally or can be forwarded upwards for processing if the endpoint is located on remote leaf.

FD VLAN- This VLAN can be used for flooding the traffic. It's kind of in the middle of BD VLAN and Encap VLAN and creates bridge between them. So multiple Encap VLANs gets mapped to BD VLAN and if traffic of the type like broadcast comes on to BD VLAN it can be flooded towards FD VLAN which further forwards to the Encap VLANs