BGP EVPN

Border Gateway Protocol (BGP) Ethernet Virtual Private Network (EVPN) provides an efficient control plane protocol for a Virtual eXtensible LAN (VXLAN).
Illustration to be inserted here by Aparna. Illustration will likely need a description of what is happening in the illustration.

Feature Overview

VXLAN is a network virtualization technology that allows for the virtualization of L2 networks over a physical network infrastructure by encapsulating L2 Ethernet frames within Layer 4 UDP packets. In a VXLAN, Virtual Tunnel End Points (VTEPs) can utilize BGP EVPN to exchange locally learned Layer 2 and Layer 3 destinations with remote VTEPs. This enables the learning of remote Media Access Control (MAC) addresses via the control plane. BGP EVPN also automates the creation of remote VTEPs and Virtual Network Identifiers (VNIs) for the VXLAN.

BGP EVPN provides the following benefits to a VXLAN:

  • Auto-discovery of remote VTEPs and their Layer 2 EVPN membership information, eliminating the need for manual configuration of remote VTEP information.
  • Distribution of locally learned MAC addresses to remote VTEPs, preventing the flooding of unknown unicast traffic.
  • Distribution of locally learned MAC-IP bindings from the ARP table to remote VTEPs.
  • Support for advanced features such as multi-homing, traffic load balancing, and ARP suppression.

In a VXLAN, the architecture is divided into two main components: the underlay network and the overlay network.

  • Underlay Network: The underlay network is the physical infrastructure that supports the VXLAN, consisting of physical switches and routers that form a logical switching fabric. It handles the transportation of VXLAN-encapsulated traffic (Layer 4) between routers and uses IP-based routing protocols, such as OSPF or IS-IS, to ensure efficient and reliable data transport.
  • Overlay Network: The overlay network runs on top of the underlay network and consists of Virtual Tunnel Endpoints (VTEPs), also known as Leafs, that encapsulate and decapsulate VXLAN packets. It provides Layer 2 and Layer 3 connectivity for tenant systems, such as customer edge devices or virtual machines, allowing them to communicate with each other.

Layer 2 Network Virtualization on Top of the Physical Network Infrastructure

Layer 2 Network Virtualization on Top of the Physical Network Infrastructure

Requirements

BGP is supported on:

  • ICX 7550 or ICX 7850 switches running FastIron software version 10.0.20 or later.
  • SmartZone release 7.1 and later.

Considerations

  • BGP EVPN is supported for ICX 7850 and ICX 7550 devices only.
  • SmartZone cannot be configured in 'IPv6 only' mode.
  • The RUCKUS implementation of BGP EVPN Multihoming supports a maximum of two homes (Dual Homing).
  • Each switch supports up to 63 ES-LAGs, with a maximum of 100 tagged VLANs per ES-LAG.
  • The Full Mesh profile supports up to 64 iBGP Neighbors.
  • The Route Reflector profile supports a maximum of 64 Route Reflector Clients.

Best Practices

  • To improve scalability and manageability, use Route Reflectors (RRs) to reduce the number of BGP sessions in the network.
  • Bind the BGP EVPN setup to a dedicated loopback address, separate from those used by other Layer 3 protocols. This isolates VXLAN traffic and simplifies troubleshooting.
  • Carefully manage Broadcast, Unknown unicast, and Multicast (BUM) traffic to prevent network congestion. Use features like IGMP snooping and multicast routing to control BUM traffic.
  • Secure your BGP sessions using authentication mechanisms like MD5. Additionally, implement access control lists (ACLs) to restrict BGP session establishment to trusted peers.
  • Plan for scalability by considering the number of VTEPs, VNIs, and the overall size of the EVPN fabric. Ensure your hardware and software can support the expected growth.
  • Deploy dual homed connections for critical devices to ensure redundancy. This setup enables all-active connectivity and improves network resilience.
  • Implement ARP suppression to minimize ARP broadcast traffic in the VXLAN fabric, enhancing network efficiency and reducing unnecessary traffic.

Prerequisites

  • The underlay network must be already configured. This means that VTEPs must be reachable to each other through an Interior Gateway Protocol (IGP), preferably OSPF.
  • The VLANs for the underlay network must already exist; creation of the BGP EVPN profiles does not create new VLANs to be assigned to the EVPN instances.
  • Just noting that you are you are using Dualhoming, Dual-homing, sual-homing, etc. Decide on one
    For BGP EVPN Dual Homing, the LAGs for the Ethernet Segments must be already configured and deployed in the corresponding switches before enabling and configuring dual homing from the controller.
  • Each switch supports up to 63 ES-LAGs, with a maximum of 100 tagged VLANs per ES-LAG.

Multiple modules in the system are involved in the implementation of BGP EVPN. These are described in subsequent sections.

In this section:

  1. BGP EVPN Multihoming Overview
    BGP EVPN multihoming enhances redundancy for BGP EVPN by providing multiple, distinct Provider Edge (PE) connections (uplinks) for Customer Edge (CE) devices. This multi-attachment capability offers redundant, all-active connectivity to the EVPN core network and extends this redundancy across the entire network connected to the core.
  2. BGP EVPN Multihoming (Dual Homing) Network Topology
  3. Creating a BGP EVPN Route Reflector Profile
    Create a BGP EVPN Route Reflector Profile to centralize distribution of client EVPN routes among VTEPs.
  4. Creating a BGP EVPN Full Mesh Profile
    Create a BGP EVPN Full Mesh Profile to decentralize distribution of client EVPN routes among VTEPs, allowing all routers in the network to communicate.
  5. Managing BGP EVPN Profiles
  6. Monitoring ICX Fabric Information
    The controller provides access to view switch-level VXLAN fabric information, including VXLAN VNI mapping, BGP neighbors, BGP EVPN attribute entries, and MAC address tables.
Parent topic: Working with Switches