Three-byte EVI in EVPN Services
This chapter provides information about the three-byte EVI in EVPN services.
Topics in this chapter include:
Applicability
The information and configuration in this chapter are based on SR OS Release 22.10.R1. The three-byte EVI is supported in EVPN services in SR OS Release 21.10.R1 and later. Three-byte EVI values can be configured in VPLS, R-VPLS, B-VPLS, and Epipe services for MPLS, VXLAN, and SRv6 instances.
Overview
- service route target (RT) auto-derivation – autonomous system number (ASN):EVI; for example, 64496:10
- service route distinguisher (RD) auto-derivation – system IP address:EVI; for example, 192.0.2.1:10
- designated forwarder (DF) election, as described in the Preference-based and Non-revertive EVPN DF Election chapter
However, in large networks, more than 65535 EVI values are required if the EVI is desired to be unique network-wide. The three-byte EVI provides up to 16777215 values and is supported in SR OS Release 21.10.R1 and later.
All DF election procedures support the extended EVI range. The RD auto-derivation is only possible for the two-byte EVI; the RT auto-derivation for the three-byte EVI can be enabled with the evi-three-byte-auto-rd command.
Auto-derived RT
The figure Auto-derived RT in RFC 8365shows the RT auto-derivation for configured EVI values in the range up to 16777215.
- the global administrator field, which contains (the lower two octets of) the autonomous system number (ASN)
- the single-bit field A, which indicates if the RT is auto-derived: A=0 for auto-derivation
- the three-bit type field, which indicates the space in which the three-byte
service ID is defined:
- 0: VID (802.1Q VLAN ID)
- 1: VXLAN
- 2: NVGRE
- 3: I-SID
- 4: EVI
- 5: dual-VID (QinQ VLAN ID)
- the four-bit D-ID field, which encodes the domain ID. For type 4 (EVI), the D-ID corresponds to the BGP instance ID in the EVPN service.
- the three-octet service ID, which is set to the EVI (for type 4)
- ASN 64496
- EVI 100002 (0x186A2)
- BGP 1 for EVPN-VXLAN; BGP 2 for EVPN-MPLS
- evi-three-byte-auto-rt enabled
- 64496:1090619042 (0x410186A2) for BGP 1
- 64496:1107396258 (0x420186A2) for BGP 2
The RT can also be configured manually, for example, 64496:100002. A manually configured RT has precedence over an auto-derived RT.
Auto-derived RD
Each BGP instance in an EVPN service has an RD. Only for EVI values smaller than or equal to 65535, the RD for BGP instance 1 can be auto-derived out of the system IP address and the EVI, for example, 192.0.2.2:10. EVI values greater than 65535 do not generate RDs automatically.
- manually configured RD or auto-RD take precedence when configured,
- if there is no manual RD or auto-RD configuration, the RD is derived from the bgp-ad>vpls-id,
- if there is no manual RD, auto-RD, or VPLS ID configuration, the RD is derived from the EVI for EVI values up to 65535 and except for bgp-mh which does not support EVI-derived RD,
*[ex:/configure service vpls "VPLS-99"]
A:admin@PE-1# commit
MINOR: MGMT_CORE #4001: configure service vpls "VPLS-99" bgp-evpn vxlan 1 admin-state - No route-distinguisher configured - configure service vpls "VPLS-99" bgp 1 route-distinguisher
MINOR: MGMT_CORE #4001: configure service vpls "VPLS-99" bgp-evpn vxlan 1 admin-state - No import route-target configured - configure service vpls "VPLS-99" bgp 1 route-target import
MINOR: MGMT_CORE #4001: configure service vpls "VPLS-99" bgp-evpn vxlan 1 admin-state - No export route-target configured - configure service vpls "VPLS-99" bgp 1 route-target export
MINOR: MGMT_CORE #4001: configure service vpls "VPLS-99" bgp-evpn vxlan 1 admin-state - No vsi-import configured - configure service vpls "VPLS-99" bgp 1 vsi-import
MINOR: MGMT_CORE #4001: configure service vpls "VPLS-99" bgp-evpn vxlan 1 admin-state - No vsi-export configured - configure service vpls "VPLS-99" bgp 1 vsi-import
MINOR: MGMT_CORE #4001: configure service vpls "VPLS-99" bgp-evpn vxlan 1 admin-state - No bgp-ad vpls-id configured to derive RD or RT - configure service
MINOR: MGMT_CORE #4001: configure service vpls "VPLS-99" bgp-evpn vxlan 1 admin-state - No bgp-evpn evi to derive RD or RT - configure service vpls "VPLS-99" bgp-evpn evi
The RD configuration can be changed dynamically. When the RD changes, the active routes for the service are withdrawn and readvertised with the new RD.
EVI RT set for AD per-ES routes
As described in the EVPN for MPLS Tunnels chapter, Auto-discovery per Ethernet Segment (AD per-ES) routes carry the ESI label and the multi-homing mode. When multiple EVIs are defined in an ES, the AD per-ES routes can be aggregated.
EVI RT set for AD per-ES routes with two-byte EVI
configure {
service {
system {
bgp {
evpn {
ad-per-es-route {
route-target-type evi-route-target-set
route-distinguisher-ip-address <ip-address>
}- EVIs from 1 to 128 – comm-val = 1
- EVIs from 129 to 256 – comm-val = 2
- ...
- EVIs from 65409 to 65535 – comm-val = 512
EVI RT set for AD per-ES routes with three-byte EVI
The command to enable AD per-ES route aggregation with extended EVI range is:
configure {
service {
system {
bgp {
evpn {
ad-per-es-route {
route-target-type evi-route-target-set
route-distinguisher-ip-address <ip-address>
extended-evi-range true
}- EVIs from 1 to 257 – comm-val = 1
- EVIs from 258 to 514 – comm-val = 2
- ...
- EVIs from 16776961 to 16777215 – comm-val = 65281
Configuration
- cards, MDAs, ports
- router interfaces
- IS-IS level 2 between core PEs PE-2, PE-3, PE-4, PE-5, and RR-7
- IS-IS level 1 between PE-1, PE-2, and PE-3
- IS-IS level 1 between PE-6, PE-4, and PE-5
- SR-ISIS between core PEs PE-2, PE-3, PE-4, and PE-5
The BGP configuration and the used policies for dual-instance VPLSs in ESs are described in the EVPN Interconnect Ethernet Segmentschapter. Policies are required to prevent loops. RR-7 acts as route reflector for the core PEs PE-2, PE-3, PE-4, and PE-5. The policy and BGP configuration on PE-2 is as follows:
# on PE-2:
configure {
policy-options {
community "SOO-DCGW-23" {
member "origin:64500:23" { }
}
community "vxlan" {
member "bgp-tunnel-encap:VXLAN" { }
}
policy-statement "add SOO to vxlan routes" {
entry 10 {
from {
family [evpn]
community {
name "vxlan"
}
}
action {
action-type accept
community {
add ["SOO-DCGW-23"]
}
}
}
default-action {
action-type accept
}
}
policy-statement "allow only mpls" {
entry 10 {
from {
family [evpn]
community {
name "vxlan"
}
}
action {
action-type reject
}
}
}
policy-statement "allow only vxlan" {
entry 10 {
from {
family [evpn]
community {
name "vxlan"
}
}
action {
action-type accept
}
}
default-action {
action-type reject
}
}
policy-statement "drop SOO-DCGW-23" {
entry 10 {
from {
family [evpn]
community {
name "SOO-DCGW-23"
}
}
action {
action-type reject
}
}
}
}
router "Base" {
autonomous-system 64496
bgp {
vpn-apply-export true
vpn-apply-import true
rapid-withdrawal true
peer-ip-tracking true
split-horizon true
rapid-update {
evpn true
}
group "WAN" {
peer-as 64496
family {
evpn true
}
export {
policy ["allow only mpls"]
}
}
group "access1" {
peer-as 64496
family {
evpn true
}
export {
policy ["allow only vxlan"]
}
}
neighbor "192.0.2.1" {
group "access1"
}
neighbor "192.0.2.3" {
group "access1"
import {
policy ["drop SOO-DCGW-23"]
}
export {
policy ["add SOO to vxlan routes"]
}
}
neighbor "192.0.2.7" {
group "WAN"
}
The all-active interconnect ES "I-ES23" is configured on PE-2 and PE-3; the single-active interconnect ES "I-ES45" is configured on PE-4 and PE-5. VPLS 1 with EVI 1 (0x1) and VPLS 2 with EVI 100002 (0x186A2) are configured on all PEs. Both VPLSs have BGP 1 for VXLAN and BGP 2 for MPLS (SR-ISIS) in the core. For VPLS 1, no extended EVI range is required. The RD can be auto-derived for BGP instance 1, but not for BGP instance 2. For VPLS 2, the EVI is greater than 65535, so the RD must always be configured (manual configuration or auto-RD). The RT is auto-derived in VPLS 1 and VPLS 2. For VPLS 2, the evi-three-byte-auto-rt command is configured to enable auto-derivation of RTs for EVI values up to 16777215. On all core PEs, evi-route-target-set is enabled for the aggregation of AD per-ES routes. The service configuration on PE-2 is as follows:
# on PE-2:
configure exclusive
service {
system {
bgp-auto-rd-range {
ip-address 192.0.2.2
community-value {
start 2000
end 2999
}
}
bgp {
evpn {
ethernet-segment "I-ES23" {
admin-state enable
type virtual
esi 00:00:00:00:00:23:23:00:00:01
multi-homing-mode all-active
df-election {
service-carving-mode manual
manual {
evi 1 {
end 200000
}
preference {
mode non-revertive
value 150
}
}
}
association {
network-interconnect-vxlan 1 {
virtual-ranges {
service-id 1 {
end 2
}
}
}
}
}
ad-per-es-route {
route-target-type evi-route-target-set
route-distinguisher-ip-address 10.0.2.2
extended-evi-range true
}
}
}
}
vpls "VPLS-1" {
admin-state enable
service-id 1
customer "1"
vxlan {
instance 1 {
vni 1
}
}
bgp 1 { # RD will be auto-derived from EVI
}
bgp 2 {
route-distinguisher auto-rd
}
bgp-evpn {
evi 1
vxlan 1 {
admin-state enable
vxlan-instance 1
}
mpls 2 {
admin-state enable
ingress-replication-bum-label true
ecmp 2
auto-bind-tunnel {
resolution filter
resolution-filter {
sr-isis true
}
}
}
}
}
vpls "VPLS-2" {
admin-state enable
service-id 2
customer "1"
vxlan {
instance 1 {
vni 2
}
}
bgp 1 {
route-distinguisher auto-rd # RD cannot be auto-derived from EVI
}
bgp 2 {
route-distinguisher auto-rd
}
bgp-evpn {
evi 100002
vxlan 1 {
admin-state enable
vxlan-instance 1
evi-three-byte-auto-rt true
}
mpls 2 {
admin-state enable
ingress-replication-bum-label true
ecmp 2
evi-three-byte-auto-rt true
auto-bind-tunnel {
resolution any
}
}
}
}
When configuring the evi-route-target-set command, the RD must be different from the RD in the auto-rd range. If not, the following error message is raised:
*[ex:/configure service system bgp evpn ad-per-es-route]
A:admin@PE-2# route-distinguisher-ip-address 192.0.2.2
*[ex:/configure service system bgp evpn ad-per-es-route]
A:admin@PE-2# commit
MINOR: SVCMGR #12: configure service system bgp-auto-rd-range ip-address - Inconsistent Value error - cannot be the same as ad-per-es-route/route-distinguisher-ip-address - configure service system bgp evpn ad-per-es-route route-distinguisher-ip-address
The following command shows the RD and RT values for both BGP instances in VPLS 1 on PE-2:
[/]
A:admin@PE-2# show service id 1 bgp
===============================================================================
BGP Information
===============================================================================
Bgp Instance : 1
Vsi-Import : None
Vsi-Export : None
Route Dist : None
Oper Route Dist : 192.0.2.2:1
Oper RD Type : derivedEvi
Rte-Target Import : None Rte-Target Export: None
Oper RT Imp Origin : derivedEvi Oper RT Import : 64496:1
Oper RT Exp Origin : derivedEvi Oper RT Export : 64496:1
ADV Service MTU : -1
Bgp Instance : 2
Vsi-Import : None
Vsi-Export : None
Route Dist : auto-rd
Oper Route Dist : 192.0.2.2:2000
Oper RD Type : auto
Rte-Target Import : None Rte-Target Export: None
Oper RT Imp Origin : derivedEvi Oper RT Import : 64496:1
Oper RT Exp Origin : derivedEvi Oper RT Export : 64496:1
ADV Service MTU : -1
PW-Template Id : None
-------------------------------------------------------------------------------
===============================================================================
RD 192.0.2.2:1 for BGP instance 1 is auto-derived whereas RD 192.0.2.2:2000 for BGP instance 2 is the result of auto-RD. RT 64496:1 is auto-derived based on the system IP address and the EVI. It is possible to configure evi-three-byte-auto-rt true in VPLS 1, even though the EVI value is smaller than 65535.
# on PE-2:
configure {
service {
vpls "VPLS-1" {
bgp-evpn {
vxlan 1 {
evi-three-byte-auto-rt true
}
mpls 2 {
evi-three-byte-auto-rt true
}
}
In this case, the auto-derivation is based on RFC 8365 and the value is 64496:1090519041 (0x41000001) for BGP 1 and 64496:1107296257 (0x42000001) for BGP 2.
[/]
A:admin@PE-2# show service id 1 bgp
===============================================================================
BGP Information
===============================================================================
Bgp Instance : 1
Vsi-Import : None
Vsi-Export : None
Route Dist : None
Oper Route Dist : 192.0.2.2:1
Oper RD Type : derivedEvi
Rte-Target Import : None Rte-Target Export: None
Oper RT Imp Origin : derivedEvi Oper RT Import : 64496:1090519041
Oper RT Exp Origin : derivedEvi Oper RT Export : 64496:1090519041
ADV Service MTU : -1
Bgp Instance : 2
Vsi-Import : None
Vsi-Export : None
Route Dist : auto-rd
Oper Route Dist : 192.0.2.2:2000
Oper RD Type : auto
Rte-Target Import : None Rte-Target Export: None
Oper RT Imp Origin : derivedEvi Oper RT Import : 64496:1107296257
Oper RT Exp Origin : derivedEvi Oper RT Export : 64496:1107296257
ADV Service MTU : -1
PW-Template Id : None
-------------------------------------------------------------------------------
===============================================================================
The auto-derived RTs on the other nodes are the same as on PE-2 when the BGP instance is the same. On PE-2, PE-3, PE-4, and PE-5, BGP 1 is for VXLAN and BGP 2 is for MPLS in the core. That way, EVPN messages can be exchanged in BGP instance 2 between the core PEs.
AD per-ES aggregation is enabled on the core nodes. The following command on PE-2 shows one AD per-ES with RD 10.0.2.4:390 (10.0.2.4 is the RD configured for evi-route-target-set and 390 is the comm-val value for the EVI range from 99974 to 100230) and one AD per-EVI with RD 192.0.2.4:2002 (auto-RD).
*A:PE-2# show router bgp routes evpn auto-disc detail
===============================================================================
BGP Router ID:192.0.2.2 AS:64496 Local AS:64496
===============================================================================
Legend -
Status codes : u - used, s - suppressed, h - history, d - decayed, * - valid
l - leaked, x - stale, > - best, b - backup, p - purge
Origin codes : i - IGP, e - EGP, ? - incomplete
===============================================================================
BGP EVPN Auto-Disc Routes
===============================================================================
---snip---
## AD per-ES
Network : n/a
Nexthop : 192.0.2.4
Path Id : None
From : 192.0.2.7
Res. Nexthop : 192.168.24.2
Local Pref. : 100 Interface Name : int-PE-2-PE-4
Aggregator AS : None Aggregator : None
Atomic Aggr. : Not Atomic MED : None
AIGP Metric : None IGP Cost : 10
Connector : None
Community : target:64496:1107396258 # auto-derived RT
esi-label:524271/Single-Active
Cluster : 192.0.2.7
Originator Id : 192.0.2.4 Peer Router Id : 192.0.2.7
Flags : Used Valid Best IGP
Route Source : Internal
AS-Path : No As-Path
EVPN type : AUTO-DISC
ESI : 00:00:00:00:00:45:45:00:00:01
Tag : MAX-ET # AD per-ES has MAX-ET
Route Dist. : 10.0.2.4:390 # RD for evi-rt-set
MPLS Label : LABEL 0
Route Tag : 0
Neighbor-AS : n/a
Orig Validation: N/A
Source Class : 0 Dest Class : 0
Add Paths Send : Default
Last Modified : 00h02m16s
---snip---
## AD per-EVI
Network : n/a
Nexthop : 192.0.2.4
Path Id : None
From : 192.0.2.7
Res. Nexthop : 192.168.24.2
Local Pref. : 100 Interface Name : int-PE-2-PE-4
Aggregator AS : None Aggregator : None
Atomic Aggr. : Not Atomic MED : None
AIGP Metric : None IGP Cost : 10
Connector : None
Community : target:64496:1107396258 bgp-tunnel-encap:MPLS
Cluster : 192.0.2.7
Originator Id : 192.0.2.4 Peer Router Id : 192.0.2.7
Flags : Used Valid Best IGP
Route Source : Internal
AS-Path : No As-Path
EVPN type : AUTO-DISC
ESI : 00:00:00:00:00:45:45:00:00:01
Tag : 0 # AD per-EVI has Ethernet tag 0
Route Dist. : 192.0.2.4:2002 # RD for BGP 2 in VPLS 2
MPLS Label : LABEL 524268
Route Tag : 0
Neighbor-AS : n/a
Orig Validation: N/A
Source Class : 0 Dest Class : 0
Add Paths Send : Default
Last Modified : 00h02m16s
---snip---
The figure Example topology with VPLS 4 and Epipe 5 shows an example topology with EVPN-MPLS in the core, all-active ES "vESI-23" on PE-2 and PE-3, and single-active ES "vESI-45" on PE-4 and PE-5. VPLS 4 with EVI 100004 is configured on all PEs with manually configured RD and RT.
The configuration on PE-2 is as follows:
# on PE-2:
configure {
service {
system {
bgp {
evpn {
ethernet-segment "vESI-23" {
admin-state enable
type virtual
esi 01:00:00:00:00:23:03:09:00:01
multi-homing-mode all-active
df-election {
es-activation-timer 3
}
association {
lag "lag-1" {
virtual-ranges {
dot1q {
q-tag 3 {
end 9
}
}
}
}
}
}
}
}
}
vpls "VPLS-4" {
admin-state enable
service-id 4
customer "1"
bgp 1 {
route-distinguisher "192.0.2.2:4"
route-target {
export "target:64496:100004"
import "target:64496:100004"
}
}
bgp-evpn {
evi 100004
mpls 1 {
admin-state enable
ingress-replication-bum-label true
ecmp 2
auto-bind-tunnel {
resolution any
}
}
}
sap lag-1:4 {
}
}With the configured RD 192.0.2.2:4 and RT 64496:100004, the following BGP information is retrieved on PE-2 for VPLS 4:
[/]
A:admin@PE-2# show service id 4 bgp
===============================================================================
BGP Information
===============================================================================
Bgp Instance : 1
Vsi-Import : None
Vsi-Export : None
Route Dist : 192.0.2.2:4
Oper Route Dist : 192.0.2.2:4
Oper RD Type : configured
Rte-Target Import : 64496:100004 Rte-Target Export: 64496:100004
Oper RT Imp Origin : configured Oper RT Import : 64496:100004
Oper RT Exp Origin : configured Oper RT Export : 64496:100004
ADV Service MTU : -1
PW-Template Id : None
-------------------------------------------------------------------------------
===============================================================================
Epipe 5 is configured on all PEs with EVI 100005 (0x186A5) and evi-three-byte-auto-rt enabled. The configuration on PE-2 is as follows:
# on PE-2:
configure {
service {
epipe "Epipe-5" {
admin-state enable
service-id 5
customer "1"
bgp 1 {
route-distinguisher auto-rd
}
sap lag-1:5 {
}
bgp-evpn {
evi 100005
local-attachment-circuit "AC-ESI-23-PE-1" {
eth-tag 231
}
remote-attachment-circuit "AC-ESI-45-PE-6" {
eth-tag 456
}
mpls 1 {
admin-state enable
ecmp 2
evi-three-byte-auto-rt true
auto-bind-tunnel {
resolution any
}
}
}
The auto-derived RT is 64496:1090619045 (0x410186A5):
[/]
A:admin@PE-2# show service id 5 bgp
===============================================================================
BGP Information
===============================================================================
Vsi-Import : None
Vsi-Export : None
Route Dist : auto-rd
Oper Route Dist : 192.0.2.2:2003
Oper RD Type : auto
Rte-Target Import : None Rte-Target Export: None
Oper RT Imp Origin : derivedEvi Oper RT Import : 64496:1090619045
Oper RT Exp Origin : derivedEvi Oper RT Export : 64496:1090619045
ADV Service MTU : -1
PW-Template Id : None
-------------------------------------------------------------------------------
===============================================================================
Instead of VXLAN or MPLS, SRv6 can be used too. As an example,VPLS 6 with EVI 100006 (0x186A6) is configured on PE-1, PE-2, PE-4, and PE-6. SRv6 is configured between PE-4 and PE-6, as described in the Segment Routing over IPv6 chapter. The configuration on PE-2 is as follows:
# on PE-2:
configure {
service {
vpls "VPLS-6" {
admin-state enable
service-id 6
customer "1"
vxlan {
instance 1 {
vni 6
}
}
segment-routing-v6 1 {
locator "PE-2_loc" {
function {
end-dt2u {
}
end-dt2m {
}
}
}
}
bgp 1 {
route-distinguisher auto-rd
}
bgp 2 {
route-distinguisher auto-rd
}
bgp-evpn {
evi 100006
segment-routing-v6 2 {
admin-state enable
ecmp 2
evi-three-byte-auto-rt true
srv6 {
instance 1
default-locator "PE-2_loc"
}
}
vxlan 1 {
admin-state enable
vxlan-instance 1
evi-three-byte-auto-rt true
}
}
}
On PE-2, RT 64496:1090619046 (0x410186A6) is auto-derived for BGP 1 and RT 64496:1107396262 (0x420186A6) for BGP 2:
[/]
A:admin@PE-2# show service id 6 bgp
===============================================================================
BGP Information
===============================================================================
Bgp Instance : 1
Vsi-Import : None
Vsi-Export : None
Route Dist : auto-rd
Oper Route Dist : 192.0.2.2:2004
Oper RD Type : auto
Rte-Target Import : None Rte-Target Export: None
Oper RT Imp Origin : derivedEvi Oper RT Import : 64496:1090619046
Oper RT Exp Origin : derivedEvi Oper RT Export : 64496:1090619046
ADV Service MTU : -1
Bgp Instance : 2
Vsi-Import : None
Vsi-Export : None
Route Dist : auto-rd
Oper Route Dist : 192.0.2.2:2005
Oper RD Type : auto
Rte-Target Import : None Rte-Target Export: None
Oper RT Imp Origin : derivedEvi Oper RT Import : 64496:1107396262
Oper RT Exp Origin : derivedEvi Oper RT Export : 64496:1107396262
ADV Service MTU : -1
PW-Template Id : None
-------------------------------------------------------------------------------
===============================================================================
Conclusion
In large networks, a three-byte EVI can be required as a unique identifier for services. RTs can be auto-derived based on a three-byte EVI, but RDs cannot be auto-derived that way.