Figure 1 shows a DC with a Layer 2 service that carries the traffic for a tenant who extends a subnet within the DC, while the DGW is the default gateway for all the hosts in the subnet. The DGW function is carried out by the 7750 SR, 7450 ESS, and 7950 XRS where an R-VPLS instance exists for that particular tenant. Within the DC, the tenant has VPLS instances in all the NVE devices where they require connectivity (such VPLS instances can be instantiated in TORs, Nuage VRS, VSG, and so on). The WAN connectivity is based on existing IP-VPN features.
In this model, the DGW routers are configured with a R-VPLS (bound to the VPRN that provides the WAN connectivity) per tenant that provides the VXLAN connectivity to the Nuage VPLS instances. This model provides inter-subnet forwarding for L2-only TORs and other L2 DC NVEs.
On the router:
The VPRN is configured with an interface bound to the backhaul R-VPLS. That interface is a regular IP interface (IP address configured or possibly a Link Local Address if IPv6 is added).
The VPRN can support other numbered interfaces to the WAN or even to the DC.
The R-VPLS is configured with the BGP, BGP-EVPN and VXLAN (VNI) parameters.
On the Nuage VSGs and NVEs:
Regular VPLS service model with BGP EVPN and VXLAN parameters.
Other considerations:
Route-type 2 routes with MACs and IPs are advertised. Some considerations about MAC+IP and ARP/ND entries are:
The 7750 SR advertises its IRB MAC+IP in a route type 2 route and possibly the VRRP vMAC+vIP if it runs VRRP and the 7750 SR is the active router. In both cases, the MACs are advertised as static MACs, therefore, protected by the receiving PEs.
If the 7750 SR VPRN interface is configured with one or more additional secondary IP addresses, they are all advertised in routes type 2, as static MACs.
The 7750 SR processes route-type 2 routes as usual, populating the FDB with the received MACs and the VPRN ARP/ND table with the MAC and IPs, respectively.
When a VPLS containing proxy-ARP/proxy-ND entries is bound to a VPRN (allow-ip-int-bind) all the proxy-ARP/proxy-ND entries are moved to the VPRN ARP/ND table. ARP/ND entries are also moved to proxy-ARP/proxy-ND entries if the VPLS is unbound.
EVPN does not program EVPN-received ARP/ND entries if the receiving VPRN has no IP addresses for the same subnet. The entries are added when the IP address for the same subnet is added.
Static ARP/ND entries have precedence over dynamic and EVPN ARP/ND entries.
VPRN interface binding to VPLS service brings down the VPRN interface operational status, if the VPRN interface MAC or the VRRP MAC matches a static-mac or OAM MAC configured in the associated VPLS service. If that is the case, a trap is generated.
Redundancy is handled by VRRP. The active 7750 SR advertises vMAC and vIP, as discussed, including the MAC mobility extended community and the sticky bit.
EVPN-enabled R-VPLS services are also supported on IES interfaces.