EVPN Intro
L2VPN - BGP VPLS - BGP EVPN - BGP
For both AFI/SAFI : 25/65 For EVPN, same AFI 25 but SAFI 70 (25/70)
Topics to be familiar with:
- Advantages of EVPN over VPLS
- Purpose of EVPN Route Types
VPLS Problems:
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Multihoming causes loops
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Only one PE can host the active IRB
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MAC addresses learned in data plane
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ARP requests flooded across service provider core
From customer point of view, VPLS and EVPN are identical but behind the scenes, everything is BGP, even MAC advertisements.
Advantages of EVPN:
- Address Learning (using BGP)
- Redundancy (Ethernet Segment Identifier - ESI)
- Local Breakout (multiple PEs can host an active IRB)
- Data plane options (MPLS, VXLAN)
Advantages of BGP MAC Learning:
- When a PE learns a local MAC address, it can immediately advertise to remote PEs
- Proxy ARP (local PE can answer local ARP requests for remote MAC addresses)
EVPN Terminology:
- EVPN Instance (EVI)
- MAC-VRF (virtual routing and forwarding)
- Ethernet Segment (ES)
- Ethernet Segment Identifier (ESI) (10-octet number, non-zero)
- Ethernet Tag ID (32 bit number, identifying the broadcast domain)
- VID
In QFX switches, by default,
bgp.evpn.0
default-switch.evpn.0 EVI
MAC addresses placed in corresponding bridge domain
Multiple bridge domains
It is possible to create custom EVIs and separate MAC addresses by VLANs in multiple ways.
MAC-VRF
EVPN Route Types
8 route types in total, but for EVPN-MPLS, we mostly use four of them.
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Type 1 Ethernet Auto-Discovery Route (sends ESI number, Mass MAC withdrawal, protection against L2 loops, load balancing through aliasing)
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Type 2 MAC/IP Advertisement Route (MAC or MAC/IP binding)
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Type 3 Inclusive Multicast Ethernet Tag (how a PE wants to receive BUM traffic) Tunnel Type: Ingress Replication , PMSI
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Type 4 Ethernet Segment Route (Designated Forwarder Election)
In Type 2, NLRI + Attributes
In Type3, NLRI + PMSI + Attributes
Provider Multicast Service Interface (PMSI)
Ingress Replication or Underlay Replication ; Junos supports only Ingress replication.
