End Host And Subnet Route Distribution - Cisco Nexus 7000 Series Configuration Manual

Configuring VXLAN BGP EVPN
• Efficient bandwidth utilization and resiliency with Active-Active multipathing
• Secure VTEPs
• BGP specific motivations

End Host and Subnet Route Distribution

Some pointers about end host MAC and IP route distribution in a VXLAN EVPN fabric are given below:
• The distributed anycast gateway also aids in supporting transparent VM mobility since post VM
move, the ARP cache entry for the default gateway is still valid.
VXLAN is supported with virtual PortChannel (vPC). This allows resiliency in connectivity for servers
attached to access switches with efficient utilization of available bandwidth. VXLAN with vPC is also
supported for access to aggregation (leaf switch to spine switch) connectivity, promoting a highly
available fabric.
In a VXLAN-EVPN fabric, traffic is only accepted from VTEPs whose information is learnt via the
BGP-EVPN control plane. Any VXLAN encapsulated traffic received from a VTEP that is not known
via the control plane will be dropped. In this way, this presents a secure fabric where traffic will only
be forwarded between VTEPs validated by the control plane. This is a major security hole in data-plane
based VXLAN flood-n-learn environments where a rogue VTEP has the potential of bringing down the
overlay network.
• Increased flexibility— EVPN address family carries both Layer-2 and Layer-3 reachability
information. So, you can build bridged overlays or routed overlays. While bridged overlays are
simpler to deploy, routed overlays are easier to scale out.
• Increased security— BGP authentication and security constructs provide more secure multi-tenancy.
• Improved convergence time— BGP being a hard-state protocol is inherently non-chatty and only
provides updates when there is a change. This greatly improves convergence time when network
failures occur.
• BGP Policies— Rich BGP policy constructs provide policy-based export and import of reachability
information. It is possible to constrain route updates where they are not needed thereby realizing
a more scalable fabric.
• Advantages of route reflectors— Increases scalability and reduces the need for a full mesh (coverage)
of BGP sessions.
A route reflector in an MP-BGP EVPN control plane acts as a central point for BGP sessions
between VTEPs. Instead of each VTEP peering with every other VTEP, the VTEPs peer with a
spine device designated as a route reflector. For redundancy purposes, an additional route reflector
is designated.
End Host and Subnet Route Distribution
Cisco Nexus 7000 Series NX-OS VXLAN Configuration Guide
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