Cisco Nexus (NX-OS)¶

The Cisco Nexus implementation supports two modes for BUM (Broadcast, Unknown unicast, Multicast) traffic replication: ingress-replication (default) and multicast.

Configuration Parameters¶

ngs_nve_interface - NVE interface name (default: nve1)
ngs_bum_replication_mode - BUM traffic replication mode (default: ingress-replication). Options: ingress-replication, multicast
ngs_mcast_group_map - Explicit VNI-to-multicast-group mappings as comma-separated VNI:group pairs. Used for pre-existing multicast group assignments. Example: 10100:239.1.1.100, 10200:239.1.1.200
ngs_mcast_group_base - Base ASM multicast group address for automatic derivation of unmapped VNIs (optional when ngs_mcast_group_map is used, required otherwise when ngs_bum_replication_mode=multicast). Example: 239.1.1.0
ngs_mcast_group_increment - Multicast group derivation method (default: vni_last_octet)

Configuration Examples¶

Ingress-Replication Mode (Default)

[genericswitch:leaf01]
device_type = netmiko_cisco_nxos
ip = 192.0.2.10
username = admin
password = password
ngs_physical_networks = datacenter1,datacenter2
ngs_nve_interface = nve1

Multicast Mode with Base IP

[genericswitch:leaf02]
device_type = netmiko_cisco_nxos
ip = 192.0.2.11
username = admin
password = password
ngs_physical_networks = datacenter1,datacenter2
ngs_bum_replication_mode = multicast
ngs_mcast_group_base = 239.1.1.0

Multicast Mode with Explicit Mapping

[genericswitch:leaf03]
device_type = netmiko_cisco_nxos
ip = 192.0.2.12
username = admin
password = password
ngs_physical_networks = datacenter1,datacenter2
ngs_bum_replication_mode = multicast
ngs_mcast_group_map = 10100:239.1.1.100, 10200:239.1.1.200
ngs_mcast_group_base = 239.1.1.0

Prerequisites¶

Both modes require VXLAN and NV overlay features enabled with the switch configured as a VTEP.

Ingress-Replication Mode¶

Your Cisco NX-OS switches must have BGP EVPN configured. This is required for both MAC/IP learning and BUM traffic replication.

Example switch configuration:

! Enable required features
feature bgp
feature vxlan
feature nv overlay

! Configure BGP EVPN
router bgp 65000
  neighbor 192.0.2.1 remote-as 65000
  address-family l2vpn evpn
    neighbor 192.0.2.1 activate
    advertise-pip

! Configure NVE interface
interface nve1
  no shutdown
  source-interface loopback0
  host-reachability protocol bgp

Multicast Mode¶

For multicast mode, in addition to BGP EVPN (used for MAC/IP learning), your fabric must have PIM Sparse Mode with Anycast RP configured.

Example switch configuration:

! Enable required features
feature bgp
feature pim
feature vxlan
feature nv overlay

! Configure PIM on underlay interfaces
interface Ethernet1/1-48
  ip pim sparse-mode

! Loopback for VTEP
interface loopback0
  ip address 10.0.0.1/32
  ip pim sparse-mode

! Anycast RP configuration (same on all RP switches)
ip pim rp-address 10.255.255.254 group-list 239.0.0.0/8

! Configure Anycast RP set (repeat for each RP)
ip pim anycast-rp 10.255.255.254 10.0.0.1
ip pim anycast-rp 10.255.255.254 10.0.0.2

! Configure BGP EVPN (for MAC/IP learning)
router bgp 65000
  neighbor 192.0.2.1 remote-as 65000
  address-family l2vpn evpn
    neighbor 192.0.2.1 activate
    advertise-pip

! Configure NVE interface
interface nve1
  no shutdown
  source-interface loopback0
  host-reachability protocol bgp

Generated Configuration¶

For each VXLAN network, the driver automatically generates the following configuration on the switch.

Ingress-Replication Mode:

! BGP EVPN control plane
evpn
  vni 10100 l2
  rd auto
  route-target both auto

! Data plane with ingress-replication
vlan 100
  vn-segment 10100
interface nve1
  member vni 10100
    ingress-replication protocol bgp

Multicast Mode:

! BGP EVPN control plane (MAC/IP learning only)
evpn
  vni 10100 l2
  rd auto
  route-target both auto

! Data plane with multicast group
vlan 100
  vn-segment 10100
interface nve1
  member vni 10100
    mcast-group 239.1.1.116

Cisco Nexus (NX-OS)