1. EVPN Interworking with IPVPN
draft-rabadan-sajassi-bess-evpn-ipvpn-interworking-01
Jorge Rabadan (Nokia)
Ali Sajassi (Cisco)
Eric Rosen (Juniper)
John Drake (Juniper)
Wen Lin (Juniper)
Jim Uttaro (AT&T)
Adam Simpson (Nokia)
IETF102, Jul 2018
Montreal

2. Refreshing the objective
VPN-IPv4 A/32
RT-5 A/32
GW1 RR
PE1
IP-VRF 1
Tenant Subnets
IP-VRF 1
A tenant network may span multiple domains where different Inter- Subnet-Forwarding SAFIs (ISF SAFIs) may provide inter-subnet connectivity.
EVPN domain-1
IPVPN domain
IP-VRF 1
GW2
This document addresses the interworking aspects between ISF-SAFIs when one of them is EVPN:
BGP route selection
Loop Prevention
Path Attribute Propagation
Route Aggregation (new in rev 01)

3. How can a DOMAIN be defined?
EVPN
GW PE
GW PE
BGP LU
ASBR
ASBR PE
IP-VRF 1
IP-VRF 1 PE PE PE
IP-VRF 1
IP-VRF 1
EVPN
IPVPN
EVPN
IP-VRF 1
IP-VRF 1
IP-VRF 1
IP-VRF 1
GW PE
GW PE
ASBR
ASBR
DOMAIN 1
DOMAIN 2
DOMAIN 3
DOMAIN 1
DOMAIN LIMITS
Two PEs are in the same Domain if there are no (tenant) IP lookups in intermediate routers.
A GW is always configured with multiple Domain_IDs
DOMAIN IDs
A GW is always configured with multiple Domain_IDs

4. Building blocks: DOMAIN types and PE types
COMPOSITE DOMAIN
Uses a multiple ISF SAFIs 1 2
REGULAR DOMAIN
Uses a single ISF SAFI
EVPN PE
IW PE
EVPN
IP-VRF 1
EVPN PE
IW PE
IPVPN PE RR
IP-VRF 1
EVPN
IPVPN
IPVPN
EVPN
IP-VRF 1
IP-VRF 1
IP-VRF 1
IPVPN
IP-VRF 1
IPVPN PE
REGULAR DOMAIN 1
REGULAR DOMAIN 2
COMPOSITE PE
Interworking PE, attached to a COMPOSITE DOMAIN, uses multiple ISF SAFIs to the RRs
REGULAR PE
Attached to a DOMAIN, uses only one ISF SAFI
GW PE
Interworking PE, attached to two DOMAINs (REGULAR or COMPOSITE), propagates the same or different ISF SAFI routes B A C

5. Domain Path Attribute (D-PATH)
A new attribute for loop protection and ISF SAFI visibility
EVPN PE1
GW PE1
GW PE2
EVPN PE2
EVPN
IPVPN
IPVPN
Length field followed by a sequence of Domain segments, where each Domain segment is represented by <DOMAIN-ID:ISF_SAFI_TYPE>
D-PATH used for Loop Prevention: any PE that imports a Prefix route MUST drop the route if its D- PATH contains a <DOMAIN- ID:ISF_SAFI_TYPE> segment, where DOMAIN-ID matches a local DOMAIN-ID
IP-VRF 1
IP-VRF 1
IP-VRF 1
IP-VRF 1
REGULAR DOMAIN 65000:3
REGULAR DOMAIN 65000:2
REGULAR DOMAIN 65000:1
EVPN RT-5
/24
VPN-IPv4
/24
[6500:1:EVPN]
EVPN RT-5
/24
[6500:2:IPVPN] [6500:1:EVPN]

6. BGP Path Propagation Across ISF-SAFIs Two modes of operation
No Propagation mode (default)
Uniform Propagation mode
Uniform Propagation:
AS_PATH
D-PATH
IBGP-only Path Attributes: LOCAL_PREF, ORIGINATOR_ID, CLUSTER_ID
MED
AIGP
Communities, (non-EVPN) Extended Communities and Large Communities

7. Route Selection Between EVPN and other ISF-SAFIs
VPN-IPv4
/32
LP 200
Between EVPN and other ISF-SAFIs
EVPN RT-5
/32
[6500:2:IPVPN] [6500:1:EVPN]
Removes from consideration the routes following the rules and the order defined in [RFC4271], with the following exceptions and in the following order:
After removing from consideration lowest Local Preference, any routes that do not have the shortest D-PATH are also removed from consideration. Routes with no D-PATH are considered to have a zero- length D-PATH.
Then regular [RFC4271] selection criteria is followed.
If at least one route still under consideration is an RT-2 route, remove from consideration any RT-5 routes.
Steps 1-3 could possibly leave Equal Cost Multi-Path (ECMP) between IP and EVPN paths.
By default, the EVPN path is considered
If ECMP across ISF SAFIs is enabled by policy, and an "IP path" and an "EVPN path" remain at the end of step 3, both path types will be used.
GW 1
IP-VRF 1
EVPN RT-2
/32
[6500:2:IPVPN]

8. EVPN and IPVPN Interworking
Changes in rev 01
Terminology section clarified and general cleaning (credits to John)
Some procedures are clarified
Route Aggregation section added

9. Aggregation of Routes to minimize the impact of host routes in DCs
And Path Attribute Propagation
EVPN RT-5
/32
Combination of the characteristics of multiple ISF routes of the same ISF SAFI in such way that a single aggregate ISF route of a different ISF SAFI can be propagated.
Done ONLY by a gateway PE.
If Uniform Propagation mode is used:
AS_PATH aggregated based on [RFC4271].
ISF routes that have different attributes of the following type codes MUST NOT be aggregated: D- PATH, LOCAL_PREF, ORIGINATOR_ID, CLUSTER_ID, MED or AIGP.
Community, Extended Community and Large Community attributes of the aggregate ISF route MUST contain all the Communities/Extended Communities/Large Communities from all of the aggregated ISF routes.
EVPN RT-5
/32
VPN-IPv4
/24
[6500:3:EVPN]
EVPN RT-5
/32
EVPN PE1
GW PE1
EVPN
IPVPN
IP-VRF 1
IP-VRF 1
REGULAR DOMAIN 65000:3
REGULAR DOMAIN 65000:2

10. Next steps
The Authors would like to request Working Group Adoption

11. Thank you