aci multisite L2 connection across sites no flooding

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aci multisite L2 connection across sites no flooding

14.01 2020 | by massimiliano

aci multisite L2 connection across sites no flooding   Layer 2 connectivity use case is probably the most important case […]



aci multisite L2 connection across sites no flooding

 

Layer 2 connectivity use case is probably the most important case supported by the Multi-Site architecture, because it provides IP mobility across sites without requiring any Layer 2 flooding

 

IP mobility support is typically needed for disaster-recovery scenarios (cold migrations) in which an endpoint, initially running inside Fabric 1, is moved to a different site.

The endpoint must maintain the same IP address it had while running in the original site

 

This use case requires all the objects (tenants, VRF instances, bridge domains, and EPGs) to stretch across the sites.

However, in the specific bridge domain configuration, you must specify that no broadcast, unknown unicast, or multicast (BUM) flooding is allowed across the sites

 

  the relocated endpoint must be allowed to communicate with endpoints that are part of the same IP subnet that may still be connected in the original site;

  to address this requirement, when the relocated endpoint sends an Address Resolution Protocol (ARP) request for a device in its same IP subnet, the multi-site architecture must deliver that ARP request in unicast mode (by performing VXLAN encapsulation directly to the leaf node at the original site in which the destination endpoint is still connected);

  this communication is possible because of the information provided across sites by the MP-BGP EVPN control plane, so the assumption is that the migrated endpoints have been discovered in the new location (a cold migration scenario).

 

 

 

 

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