EVPN VXLAN - Why do we need Type 5 Routes

[jeanprochette]

Why do we need Type 5 Routes in EVPN VXLAN ? If a host on a VNI wants to reach a host not belonging to a VNI, cant the VTEP just lookup at the ospf or ipv4 unicast bgp routing table to search for a route ?

[M02@rt37 · Accepted solution]

Hello @jeanprochette,

In EVPN VxLAN networks, EVPN Type 5 routes are used for L3 routing between different VNIs when those VNIs belong to the same IP subnet. These routes provide the necessary L3 reachability information within the VxLAN overlay.

When a host in one VNI wants to communicate with a host in another VNI within the same IP subnet, the VTEP uses EVPN Type 5 routes to determine the appropriate egress VTEP for routing the L3 traffic.

So, in an EVPN VxLAN network, when hosts in different VNIs need to communicate with each other within the same IP subnet, EVPN Type 5 routes are used to provide the L3 routing information within the VxLAN overlay.

[jeanprochette]

Hi, thank you very much for the quick response. Now i understand.

Very much appreciated

[AshSe]

Where Route Type-2 provides Host Route Advertisement. Route Type-5 provides IP Prefix/ Subnet Route Advertisements.

Route Type-5 provides Internal and External Subnet  Prefixes that include:

• IP Prefix
• MPLS Label (L3VNI)
• Route Target for IP-VRF
• Router MAC

VXLAN Route Type-5 provides IP Prefix Learning via:

• via BGP with VRF-Lite
• via LISP on Nexus 7000/7700
• via other routing protocol (static  or dynamic)

NLRI bit count size of Type-5 Routes is 224 bits