EVPN IRB Support
EVPN IRB supports the following scenarios:
• In single-homing scenario, only physical, VLAN, .1q, .1ad, or QinQ access methods are supported.
• In dual-homing scenario, only active-active mode is supported.
• In dual-homing scenario, only two PE gateways in a redundancy group are supported.
• Both IPv4 and IPv6 are supported.
Distributed Anycast Gateway
EVPN IRB for the given subnet is configured on all the EVPN PEs that are hosted on this subnet. To facilitate
optimal routing while supporting transparent virtual machine mobility, hosts are configured with a single
default gateway address for their local subnet. That single (anycast) gateway address is configured with a
single (anycast) MAC address on all EVPN PE nodes locally supporting that subnet. This process is repeated
for each locally defined subnet requires Anycast Gateway support.
The host-to-host Layer 3 traffic, similar to Layer 3 VPN PE-PE forwarding, is routed on the source EVPN
PE to the destination EVPN PE next-hop over an IP or MPLS tunnel, where it is routed again to the directly
connected host. Such forwarding is also known as Symmetric IRB because the Layer 3 flows are routed at
both the source and destination EVPN PEs.
The following solutions are part of the Distributed Anycast Gateway feature:
EVPN IRB with Active-Active Multi-Homing with Subnet Stretch or
Host-Routing across the Fabric
For a bridge domain or subnet that is stretched across remote EVPN PEs, both /32 host routes and MAC routes
are distributed in a EVPN overlay control plane to enable Layer 2 and Layer 2 traffic to the end points in a
stretched subnet.
This type of multi-homing has the following characteristics:
• All-active MC-LAG on access
• Layer 2 or Layer 3 ECMP for the fabric for dual-homed hosts based on Route Type 1 and Route Type
2
• Layer 3 unipath over the Fabric for single-homed hosts based on Route Type 2
• Layer 2 subnet stretch over the fabric
• Layer 2 stretch within redundancy group of leafs with orphan ports
MAC and IP Unicast Control Plane
This use case has following types:
L2VPN and Ethernet Services Configuration Guide for Cisco ASR 9000 Series Routers, IOS XR Release 6.3.x
587
Configure EVPN IRB
EVPN IRB Support
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