Considerations For Vxlan Deployment - Cisco Nexus 9000 Series Configuration Manual

Guidelines and Limitations for VXLAN

Considerations for VXLAN Deployment

• A loopback address is required when using the source-interface config command. The loopback address
represents the local VTEP IP.
• During boot-up of a switch (7.0(3)I2(2) and later), you can use the source-interface hold-down-time
hold-down-time command to suppress advertisement of the NVE loopback address until the overlay has
converged. The range for the hold-down-time is 0 - 2147483647 seconds. The default is 300 seconds.
• To establish IP multicast routing in the core, IP multicast configuration, PIM configuration, and RP
configuration is required.
• VTEP to VTEP unicast reachability can be configured through any IGP protocol.
• In VXLAN flood and learn mode (7.0(3)I1(2) and earlier), the default gateway for VXLAN VLANs
should be provisioned on external routing devices.
In VXLAN flood and learn mode (7.0(3)I2(1) and later), the default gateway for VXLAN VLAN is
recommended to be a centralized gateway on a pair of VPC devices with FHRP (First Hop Redundancy
Protocol) running between them.
In BGP EVPN, it is recommended to use the anycast gateway feature on all VTEPs.
• For flood and learn mode (7.0(3)I2(1) and later), only a centralized Layer 3 gateway is supported. Anycast
gateway is not supported. The recommended Layer 3 gateway design would be a pair of switches in
VPC to be the Layer 3 centralized gateway with FHRP protocol running on the SVIs. The same SVI's
cannot span across multiple VTEPs even with different IP addresses used in the same subnet.
Note
Note
• When configuring ARP suppression with BGP-EVPN, use the hardware access-list tcam region
arp-ether size double-wide command to accommodate ARP in this region. (You must decrease the size
of an existing TCAM region before using this command.)
Note
• When configuring BGP-EVPN on Cisco Nexus 9300-EX switches and Cisco Nexus 9500 switches with
N9K-X9732C-EX line cards, use the system routing template-vxlan-scale command. Performing this
Cisco Nexus 9000 Series NX-OS VXLAN Configuration Guide, Release 7.x
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When configuring SVI with flood and learn mode on the central gateway leaf, it is
mandatory to configure hardware access-list tcam region arp-ether size double-wide.
(You must decrease the size of an existing TCAM region before using this command.)
For example:
hardware access-list tcam region arp-ether 256 double-wide
Configuring the hardware access-list tcam region arp-ether size double-wide is not
required on Cisco Nexus 9200 Series switches.
This step is required for Cisco Nexus 9300 switches (NFE/ALE) and Cisco Nexus 9500
switches with N9K-X9564PX, N9K-X9564TX, and N9K-X9536PQ line cards. This
step is not needed with Cisco Nexus 9200 switches, Cisco Nexus 9300-EX switches,
or Cisco Nexus 9500 switches with N9K-X9732C-EX line cards.
Configuring VXLAN