Single-Domain SR-TE その９（EVPN VPWS Preferred Path over SR-TE Policy）

EVPN VPWS Preferred Path over SR-TE Policy が理解できたので自分のメモ用にアウトプットします。

1. EVPN VPWS Preferred Path over SR-TE Policy
2. Topology
3. Config
4. EVPN VPWS Preferred Path over SR-TE Policy の実装
5. 検証
5.1 fallback enabled 検証
5.2 fallback disable 検証
6. 参考

1. EVPN VPWS Preferred Path over SR-TE Policy

一言で言うと VPWS に SR-TE を関連付けることです。

2. Topology

3. Config

h_N1（主役① PEルータ;fallback enable）

hostname h_N1
group CCIE-ISIS
 router isis '.*'
  is-type level-2-only
  address-family ipv4 unicast
   metric-style wide
   segment-routing mpls
  !
  interface 'Gi.*'
   point-to-point
   address-family ipv4 unicast
   !
  !
  interface 'Loopback .*'
   address-family ipv4 unicast
   !
  !
 !
end-group
!
vrf A
 rd 10:1
 address-family ipv4 unicast
  import route-target
   200:1
  !
  export route-target
   100:1
  !
 !
!
interface Loopback0
 ipv4 address 1.1.1.1 255.255.255.255
!
interface MgmtEth0/RP0/CPU0/0
 shutdown
!
interface GigabitEthernet0/0/0/0
 ipv4 address 10.1.2.1 255.255.255.0
!
interface GigabitEthernet0/0/0/1.10 l2transport
 encapsulation dot1q 10
!
interface GigabitEthernet0/0/0/1.20
 vrf A    
 ipv4 address 198.51.100.1 255.255.255.0
 encapsulation dot1q 20
!
interface GigabitEthernet0/0/0/2
 ipv4 address 10.1.3.1 255.255.255.0
!
interface GigabitEthernet0/0/0/3
 shutdown
!
interface GigabitEthernet0/0/0/4
 shutdown
!
route-policy PASS
  pass
end-policy
!
router isis 1
 apply-group CCIE-ISIS
 net 49.0001.0000.0000.0001.00
 address-family ipv4 unicast
 !
 interface Loopback0
  address-family ipv4 unicast
   prefix-sid index 1
  !
 !
 interface GigabitEthernet0/0/0/0
 !
 interface GigabitEthernet0/0/0/2
 !
!
router bgp 10
 bgp router-id 1.1.1.1
 address-family vpnv4 unicast
 !
 address-family l2vpn evpn
 !
 neighbor 6.6.6.6
  remote-as 10
  update-source Loopback0
  address-family vpnv4 unicast
  !
  address-family l2vpn evpn
  !
 !
 vrf A    
  rd 10:1
  address-family ipv4 unicast
  !
  neighbor 198.51.100.100
   remote-as 100
   address-family ipv4 unicast
    route-policy PASS in
    route-policy PASS out
   !
  !
 !
!
evpn
 evi 100
  advertise-mac
  !
 !
!
l2vpn
 pw-class PW60000
  encapsulation mpls
   preferred-path sr-te policy srte_c_60000_ep_6.6.6.6 fallback enable
  !       
 !
 xconnect group EVPN_VPWS
  p2p EVPN_1
   interface GigabitEthernet0/0/0/1.10
   neighbor evpn evi 1010 target 60 source 10
    pw-class PW60000
   !
  !
 !
!
mpls oam
!
segment-routing
 traffic-eng
  segment-list EVPN_VPWS_PREFER
   index 10 mpls label 16002
   index 20 mpls label 16003
   index 30 mpls label 16004
   index 40 mpls label 16005
   index 50 mpls label 16006
  !
  policy LIGHTNING
   binding-sid mpls 61000
   color 60000 end-point ipv4 6.6.6.6
   autoroute
    include ipv4 6.6.6.6/32
   !
   candidate-paths
    preference 100
     explicit segment-list EVPN_VPWS_PREFER
     !
    !
   !
  !
 !
!
mpls label range table 0 1001001 1001999
end

h_N1（主役① PEルータ;fallback disable）

hostname h_N1
group CCIE-ISIS
 router isis '.*'
  is-type level-2-only
  address-family ipv4 unicast
   metric-style wide
   segment-routing mpls
  !
  interface 'Gi.*'
   point-to-point
   address-family ipv4 unicast
   !
  !
  interface 'Loopback .*'
   address-family ipv4 unicast
   !
  !
 !
end-group
!
vrf A
 rd 10:1
 address-family ipv4 unicast
  import route-target
   200:1
  !
  export route-target
   100:1
  !
 !
!
interface Loopback0
 ipv4 address 1.1.1.1 255.255.255.255
!
interface MgmtEth0/RP0/CPU0/0
 shutdown
!
interface GigabitEthernet0/0/0/0
 ipv4 address 10.1.2.1 255.255.255.0
!
interface GigabitEthernet0/0/0/1.10 l2transport
 encapsulation dot1q 10
!
interface GigabitEthernet0/0/0/1.20
 vrf A    
 ipv4 address 198.51.100.1 255.255.255.0
 encapsulation dot1q 20
!
interface GigabitEthernet0/0/0/2
 ipv4 address 10.1.3.1 255.255.255.0
!
interface GigabitEthernet0/0/0/3
 shutdown
!
interface GigabitEthernet0/0/0/4
 shutdown
!
route-policy PASS
  pass
end-policy
!
router isis 1
 apply-group CCIE-ISIS
 net 49.0001.0000.0000.0001.00
 address-family ipv4 unicast
 !
 interface Loopback0
  address-family ipv4 unicast
   prefix-sid index 1
  !
 !
 interface GigabitEthernet0/0/0/0
 !
 interface GigabitEthernet0/0/0/2
 !
!
router bgp 10
 bgp router-id 1.1.1.1
 address-family vpnv4 unicast
 !
 address-family l2vpn evpn
 !
 neighbor 6.6.6.6
  remote-as 10
  update-source Loopback0
  address-family vpnv4 unicast
  !
  address-family l2vpn evpn
  !
 !
 vrf A    
  rd 10:1
  address-family ipv4 unicast
  !
  neighbor 198.51.100.100
   remote-as 100
   address-family ipv4 unicast
    route-policy PASS in
    route-policy PASS out
   !
  !
 !
!
evpn
 evi 100
  advertise-mac
  !
 !
!
l2vpn
 pw-class PW60000
  encapsulation mpls
   preferred-path sr-te policy srte_c_60000_ep_6.6.6.6 fallback disable
  !       
 !
 xconnect group EVPN_VPWS
  p2p EVPN_1
   interface GigabitEthernet0/0/0/1.10
   neighbor evpn evi 1010 target 60 source 10
    pw-class PW60000
   !
  !
 !
!
mpls oam
!
segment-routing
 traffic-eng
  segment-list EVPN_VPWS_PREFER
   index 10 mpls label 16002
   index 20 mpls label 16003
   index 30 mpls label 16004
   index 40 mpls label 16005
   index 50 mpls label 16006
  !
  policy LIGHTNING
   binding-sid mpls 61000
   color 60000 end-point ipv4 6.6.6.6
   autoroute
    include ipv4 6.6.6.6/32
   !
   candidate-paths
    preference 100
     explicit segment-list EVPN_VPWS_PREFER
     !
    !
   !
  !
 !
!
mpls label range table 0 1001001 1001999
end

h_N2（脇役）

hostname h_N2
group CCIE-ISIS
 router isis '.*'
  is-type level-2-only
  address-family ipv4 unicast
   metric-style wide
   segment-routing mpls
  !
  interface 'Gi.*'
   point-to-point
   address-family ipv4 unicast
   !
  !
  interface 'Loopback .*'
   address-family ipv4 unicast
   !
  !
 !
end-group
!
interface Loopback0
 ipv4 address 2.2.2.2 255.255.255.255
!
interface MgmtEth0/RP0/CPU0/0
 shutdown
!
interface GigabitEthernet0/0/0/0
 ipv4 address 10.1.2.2 255.255.255.0
!
interface GigabitEthernet0/0/0/1
 ipv4 address 10.2.3.2 255.255.255.0
!
interface GigabitEthernet0/0/0/2
 ipv4 address 10.2.4.2 255.255.255.0
!
router isis 1
 apply-group CCIE-ISIS
 net 49.0001.0000.0000.0002.00
 address-family ipv4 unicast
 !
 interface Loopback0
  address-family ipv4 unicast
   prefix-sid index 2
  !
 !
 interface GigabitEthernet0/0/0/0
 !
 interface GigabitEthernet0/0/0/1
 !
 interface GigabitEthernet0/0/0/2
 !
!
mpls oam
!
mpls label range table 0 1002001 1002999
end

h_N3（脇役）

hostname h_N3
group CCIE-ISIS
 router isis '.*'
  is-type level-2-only
  address-family ipv4 unicast
   metric-style wide
   segment-routing mpls
  !
  interface 'Gi.*'
   point-to-point
   address-family ipv4 unicast
   !
  !
  interface 'Loopback .*'
   address-family ipv4 unicast
   !
  !
 !
end-group
!
interface Loopback0
 ipv4 address 3.3.3.3 255.255.255.255
!
interface MgmtEth0/RP0/CPU0/0
 shutdown
!
interface GigabitEthernet0/0/0/0
 ipv4 address 10.1.3.3 255.255.255.0
!
interface GigabitEthernet0/0/0/1
 ipv4 address 10.2.3.3 255.255.255.0
!
interface GigabitEthernet0/0/0/2
 ipv4 address 10.3.5.3 255.255.255.0
!
interface GigabitEthernet0/0/0/3
 ipv4 address 10.3.4.3 255.255.255.0
!
router isis 1
 apply-group CCIE-ISIS
 net 49.0001.0000.0000.0003.00
 address-family ipv4 unicast
 !
 interface Loopback0
  address-family ipv4 unicast
   prefix-sid index 3
  !
 !
 interface GigabitEthernet0/0/0/0
 !
 interface GigabitEthernet0/0/0/1
 !
 interface GigabitEthernet0/0/0/2
 !
 interface GigabitEthernet0/0/0/3
 !
!
mpls oam
!
mpls label range table 0 1003001 1003999
end

h_N4（脇役）

hostname h_N4
group CCIE-ISIS
 router isis '.*'
  is-type level-2-only
  address-family ipv4 unicast
   metric-style wide
   segment-routing mpls
  !
  interface 'Gi.*'
   point-to-point
   address-family ipv4 unicast
   !
  !
  interface 'Loopback .*'
   address-family ipv4 unicast
   !
  !
 !
end-group
!
interface Loopback0
 ipv4 address 4.4.4.4 255.255.255.255
!
interface MgmtEth0/RP0/CPU0/0
 shutdown
!
interface GigabitEthernet0/0/0/0
 ipv4 address 10.2.4.4 255.255.255.0
!
interface GigabitEthernet0/0/0/1
 ipv4 address 10.4.5.4 255.255.255.0
!
interface GigabitEthernet0/0/0/2
 ipv4 address 10.4.6.4 255.255.255.0
!
interface GigabitEthernet0/0/0/3
 ipv4 address 10.3.4.4 255.255.255.0
!
router isis 1
 apply-group CCIE-ISIS
 net 49.0001.0000.0000.0004.00
 address-family ipv4 unicast
 !
 interface Loopback0
  prefix-attributes anycast
  address-family ipv4 unicast
   prefix-sid index 4
  !
 !
 interface GigabitEthernet0/0/0/0
 !
 interface GigabitEthernet0/0/0/1
 !
 interface GigabitEthernet0/0/0/2
 !
 interface GigabitEthernet0/0/0/3
 !
!
mpls oam
!
mpls label range table 0 1004001 1004999
end

h_N5（脇役）

hostname h_N5
group CCIE-ISIS
 router isis '.*'
  is-type level-2-only
  address-family ipv4 unicast
   metric-style wide
   segment-routing mpls
  !
  interface 'Gi.*'
   point-to-point
   address-family ipv4 unicast
   !
  !
  interface 'Loopback .*'
   address-family ipv4 unicast
   !
  !
 !
end-group
!
interface Loopback0
 ipv4 address 5.5.5.5 255.255.255.255
!
interface MgmtEth0/RP0/CPU0/0
 shutdown
!
interface GigabitEthernet0/0/0/0
 ipv4 address 10.3.5.5 255.255.255.0
!
interface GigabitEthernet0/0/0/1
 ipv4 address 10.4.5.5 255.255.255.0
!
interface GigabitEthernet0/0/0/2
 ipv4 address 10.5.6.5 255.255.255.0
!
router isis 1
 apply-group CCIE-ISIS
 net 49.0001.0000.0000.0005.00
 address-family ipv4 unicast
 !
 interface Loopback0
  prefix-attributes anycast
  address-family ipv4 unicast
   prefix-sid index 5
  !
 !
 interface GigabitEthernet0/0/0/0
 !
 interface GigabitEthernet0/0/0/1
 !
 interface GigabitEthernet0/0/0/2
 !
!
mpls oam
!
mpls label range table 0 1005001 1005999
end

h_N6（準主役① PEルータ）

hostname h_N6
group CCIE-ISIS
 router isis '.*'
  is-type level-2-only
  address-family ipv4 unicast
   metric-style wide
   segment-routing mpls
  !
  interface 'Gi.*'
   point-to-point
   address-family ipv4 unicast
   !
  !
  interface 'Loopback .*'
   address-family ipv4 unicast
   !
  !
 !
end-group
!
vrf B
 rd 10:6
 address-family ipv4 unicast
  import route-target
   100:1
  !
  export route-target
   200:1
  !
 !
!
interface Loopback0
 ipv4 address 6.6.6.6 255.255.255.255
!
interface MgmtEth0/RP0/CPU0/0
 shutdown
!
interface GigabitEthernet0/0/0/0
 ipv4 address 10.4.6.6 255.255.255.0
!
interface GigabitEthernet0/0/0/1.10 l2transport
 encapsulation dot1q 10
!
interface GigabitEthernet0/0/0/1.30
 vrf B
 ipv4 address 203.0.113.6 255.255.255.0
 encapsulation dot1q 30
!
interface GigabitEthernet0/0/0/2
 ipv4 address 10.5.6.6 255.255.255.0
!
interface GigabitEthernet0/0/0/3
 shutdown
!
interface GigabitEthernet0/0/0/4
 shutdown
!
route-policy PASS
  pass
end-policy
!
router isis 1
 apply-group CCIE-ISIS
 net 49.0001.0000.0000.0006.00
 address-family ipv4 unicast
 !
 interface Loopback0
  address-family ipv4 unicast
   prefix-sid index 6
  !
 !
 interface GigabitEthernet0/0/0/0
 !
 interface GigabitEthernet0/0/0/2
 !
!         
router bgp 10
 bgp router-id 6.6.6.6
 address-family vpnv4 unicast
 !
 address-family l2vpn evpn
 !
 neighbor 1.1.1.1
  remote-as 10
  update-source Loopback0
  address-family vpnv4 unicast
  !
  address-family l2vpn evpn
  !
 !
 vrf B
  rd 10:6
  address-family ipv4 unicast
  !
  neighbor 203.0.113.200
   remote-as 200
   address-family ipv4 unicast
    route-policy PASS in
    route-policy PASS out
   !
  !
 !
!
evpn
 evi 100
  advertise-mac
  !
 !
!
l2vpn
 xconnect group EVPN_VPWS
  p2p EVPN_1
   interface GigabitEthernet0/0/0/1.10
   neighbor evpn evi 1010 target 10 source 60
   !
  !
 !
!
mpls oam
!
mpls label range table 0 1006001 1006999
end

h_CE1（準主役② CEルータ）

hostname CE1
!
no ip domain lookup
!
interface Loopback0
 ip address 100.100.100.100 255.255.255.255
!
interface Loopback110
 ip address 1.1.1.10 255.255.255.255
!
interface GigabitEthernet1
 no ip address
!
interface GigabitEthernet1.10
 encapsulation dot1Q 10
 ip address 192.0.2.100 255.255.255.0
!
interface GigabitEthernet1.20
 encapsulation dot1Q 20
 ip address 198.51.100.100 255.255.255.0
!
router bgp 100
 bgp router-id 100.100.100.100
 bgp log-neighbor-changes
 network 1.1.1.10 mask 255.255.255.255
 neighbor 198.51.100.1 remote-as 10
!
line con 0
 exec-timeout 0 0
!
end

h_CE2（準主役③ CEルータ）

hostname CE2
!
no ip domain lookup
!
interface Loopback0
 ip address 200.200.200.200 255.255.255.255
!
interface Loopback210
 ip address 2.2.2.10 255.255.255.255
!
interface Loopback220
 ip address 2.2.2.20 255.255.255.255
!
interface GigabitEthernet1
 no ip address
!
interface GigabitEthernet1.10
 encapsulation dot1Q 10
 ip address 192.0.2.200 255.255.255.0
!
interface GigabitEthernet1.30
 encapsulation dot1Q 30
 ip address 203.0.113.200 255.255.255.0
!
router bgp 200
 bgp router-id 200.200.200.200
 bgp log-neighbor-changes
 network 2.2.2.10 mask 255.255.255.255
 network 2.2.2.20 mask 255.255.255.255
 neighbor 203.0.113.6 remote-as 10
!
line con 0
 exec-timeout 0 0
!
end

4. EVPN VPWS Preferred Path over SR-TE Policy の実装

L2VPN が実装されている前提で話を進めます。 → Single-Domain SR-TE その６（LxVPN over SR）完了した状態からスタートします。

実装の流れは、① Head-end で explicit Path を定義し、② SR-TEのポリシーを定義します。③ 経路(Candidate-paths)の候補を②で指定した path list から選択します。 ④ Head-end で Pseudowire class template を定義し、⑤ L2VPN(E-LINE) で Pseudowire class template を指定します。

4.1 PEルータ（Head-end）

4.1.1 explicit Path の定義

① Segment Routing を定義します。

RP/0/RP0/CPU0:h_N1(config)#
  segment-routing            Segment Routing

② Segment Routing で Traffic Engineering を定義します。

RP/0/RP0/CPU0:h_N1(config-sr)#?
  traffic-eng         Segment Routing Traffic Engineering

③ Segment-list configuration でSegment-list名(任意：EVPN_VPWS_PREFER)を定義します。

RP/0/RP0/CPU0:h_N1(config-sr-te)#?
  segment-list        Segment-list configuration
RP/0/RP0/CPU0:h_N1(config-sr-te)#segment-list ?
  name  Segment-list name
  WORD  Identifying name for segment-list
RP/0/RP0/CPU0:h_N1(config-sr-te)#segment-list EVPN_VPWS_PREFER

④ SR-TEで経路を明示的に定義します。

RP/0/RP0/CPU0:h_N1(config-sr-te-sl)#?
  index               Next entry index
RP/0/RP0/CPU0:h_N1(config-sr-te-sl)#index ?
  <1-65535>  Index number
RP/0/RP0/CPU0:h_N1(config-sr-te-sl)#index 10 ?
  mpls  MPLS configuration
RP/0/RP0/CPU0:h_N1(config-sr-te-sl)#index 10 mpls ?
  label      MPLS label configuration
RP/0/RP0/CPU0:h_N1(config-sr-te-sl)#index 10 mpls label ?
  <0-1048575>  MPLS label value
RP/0/RP0/CPU0:h_N1(config-sr-te-sl)#index 10 mpls label 16002

EVPN_VPWS_PREFER N1→N2→N3→N4→N5→N6 を作ります。

segment-routing
 traffic-eng
  segment-list EVPN_VPWS_PREFER
   index 10 mpls label 16002
   index 20 mpls label 16003
   index 30 mpls label 16004
   index 40 mpls label 16005
   index 50 mpls label 16006
  !
 !
!

4.1.2 SR-TE Policy の定義

SR-TE Policy を以下のように定義します。
a) ポリシー名：LIGHTNING
b) B-SID(任意)：61000
c) color ：60000
d) Tail-End ：6.6.6.6(h_N6)

SR-TEは、a)ポリシー名とc)カラー、d)Tail-Endの指定が必須です。

① 先ずはポリシー名を定義します。

RP/0/RP0/CPU0:h_N1(config-sr-te)#policy ?
  WORD  Identifying name for policy with max 59 characters
RP/0/RP0/CPU0:h_N1(config-sr-te)#policy LIGHTNING

② B-SID(binding-sid)は任意設定です。 ※ SR-TE Policy自体に割り当てられたSIDをB-SID(binding-sid)と呼びます。

RP/0/RP0/CPU0:h_N1(config-sr-te-policy)#?
  binding-sid              Binding Segment Identifier
RP/0/RP0/CPU0:h_N1(config-sr-te-policy)#binding-sid ?
  mpls  MPLS label
RP/0/RP0/CPU0:h_N1(config-sr-te-policy)#binding-sid mpls ?
  <16-1048575>  MPLS label
RP/0/RP0/CPU0:h_N1(config-sr-te-policy)#binding-sid mpls 61000

③ 次にカラーとTail-Endを指定します。

RP/0/RP0/CPU0:h_N1(config-sr-te-policy)#?
  color                    Specify color for policy
RP/0/RP0/CPU0:h_N1(config-sr-te-policy)#color ?
  <1-4294967295>  Color value
RP/0/RP0/CPU0:h_N1(config-sr-te-policy)#color 60000 ?
  end-point  Policy endpoint
RP/0/RP0/CPU0:h_N1(config-sr-te-policy)#color 60000 end-point ?
  ipv4  IPv4 address
RP/0/RP0/CPU0:h_N1(config-sr-te-policy)#color 60000 end-point ipv4 ?
  A.B.C.D  IPv4 endpoint address
RP/0/RP0/CPU0:h_N1(config-sr-te-policy)#color 60000 end-point ipv4 6.6.6.6 ?
  <cr>

④ SR-TEポリシーで作成したLSP経由でパケットを転送させるため、autorouteを定義します。
端的に言うと、For traffic steering toward h_N6 ってことです。

RP/0/RP0/CPU0:h_N1(config-sr-te-policy)#?
  autoroute                Autoroute configuration
RP/0/RP0/CPU0:h_N1(config-sr-te-policy)#autoroute 
RP/0/RP0/CPU0:h_N1(config-sr-te-policy-autoroute)#?
  include             Prefixes for which IGP routes will be installed
RP/0/RP0/CPU0:h_N1(config-sr-te-policy-autoroute)#include ?
  all   Include all eligible prefixes
  ipv4  IPv4 address family
RP/0/RP0/CPU0:h_N1(config-sr-te-policy-autoroute)#include ipv4 ?
  A.B.C.D/length  IP prefix route to include
RP/0/RP0/CPU0:h_N1(config-sr-te-policy-autoroute)#include ipv4 6.6.6.6/32

4.1.3 Candidate-paths の定義

Candidate-paths を以下のように定義します。
a) preference ：100
b) explicit path ：EVPN_VPWS_PREFER

preference と指定する経路リストをセットで指定します。

RP/0/RP0/CPU0:h_N1(config-sr-te-policy)#?
  candidate-paths          Candidate-paths configuration
RP/0/RP0/CPU0:h_N1(config-sr-te-policy)#candidate-paths 
RP/0/RP0/CPU0:h_N1(config-sr-te-policy-path)#?
  preference          Policy path-option preference entry
RP/0/RP0/CPU0:h_N1(config-sr-te-policy-path)#preference ?
  <1-65535>  Path-option preference
RP/0/RP0/CPU0:h_N1(config-sr-te-policy-path)#preference 100 
RP/0/RP0/CPU0:h_N1(config-sr-te-policy-path-pref)#?
  explicit            Preconfigured path
RP/0/RP0/CPU0:h_N1(config-sr-te-policy-path-pref)#explicit ?
  segment-list  Specify Segment-list
RP/0/RP0/CPU0:h_N1(config-sr-te-policy-path-pref)#explicit segment-list ?
  EXPLICIT_LIST  Identifying name for segment-list
  WORD           Identifying name for segment-list
RP/0/RP0/CPU0:h_N1(config-sr-te-policy-path-pref)#explicit segment-list EVPN_VPWS_PREFER

4.1.4 Pseudowire class template の定義

① 事前に SR-TE のポリシー名を控えておきます。今回は”srte_c_60000_ep_6.6.6.6 ”です。

   RP/0/RP0/CPU0:h_N1#show segment-routing traffic-eng policy candidate-path name LIGHTNING | i Name
   Sun May 28 15:34:47.209 UTC
★   Name: srte_c_60000_ep_6.6.6.6
         Name: LIGHTNING
   RP/0/RP0/CPU0:h_N1#

② L2VPN の Pseudowire class で優先させる SR-TE を指定します。
途中、①で控えた SR-TE のポリシー名を使います★

   RP/0/RP0/CPU0:h_N1(config)#?
     l2vpn                      Configure l2vpn commands
   RP/0/RP0/CPU0:h_N1(config-l2vpn)#?
     pw-class                   Pseudowire class template
   RP/0/RP0/CPU0:h_N1(config-l2vpn)#pw-class ?
     WORD  Pseudowire-class name (Max character length: 32)
   RP/0/RP0/CPU0:h_N1(config-l2vpn)#pw-class PW60000 
   RP/0/RP0/CPU0:h_N1(config-l2vpn-pwc)#?
     encapsulation       Pseudowire encapsulation
   RP/0/RP0/CPU0:h_N1(config-l2vpn-pwc)#encapsulation ?
     mpls    Set pseudowire encapsulation to MPLS
   RP/0/RP0/CPU0:h_N1(config-l2vpn-pwc)#encapsulation mpls 
   RP/0/RP0/CPU0:h_N1(config-l2vpn-pwc-mpls)#?
     preferred-path      Preferred path tunnel settings
   RP/0/RP0/CPU0:h_N1(config-l2vpn-pwc-mpls)#preferred-path ?
     sr-te      Use segment-routing traffic-engineering for preferred path
   RP/0/RP0/CPU0:h_N1(config-l2vpn-pwc-mpls)#preferred-path sr-te ?
     policy  Specify SR TE policy for preferred path
   RP/0/RP0/CPU0:h_N1(config-l2vpn-pwc-mpls)#preferred-path sr-te policy ?
     WORD  Name of SR TE policy
★ RP/0/RP0/CPU0:h_N1(config-l2vpn-pwc-mpls)#preferred-path sr-te policy srte_c_60000_ep_6.6.6.6
   RP/0/RP0/CPU0:h_N1(config-l2vpn-pwc-mpls)#show
   Sun May 28 15:48:27.562 UTC
   l2vpn
    pw-class PW60000
     encapsulation mpls
      preferred-path sr-te policy srte_c_60000_ep_6.6.6.6
     !
    !
   !
   
   RP/0/RP0/CPU0:h_N1(config-l2vpn-pwc-mpls)#commit 
   Sun May 28 15:48:33.683 UTC
   RP/0/RP0/CPU0:h_N1(config-l2vpn-pwc-mpls)#

4.1.5 L2VPN(E-LINE) の定義

③ L2VPN(E-LINE)の定義に、Pseudowire class template を指定します。
xconnect Group：EVPN_VPWS
p2p xconnect ：EVPN_1
AC interface ：GigabitEthernet0/0/0/1.10
EVI ：1010
remote AC ：60
local AC ：10
★ Pseudowire class：PW60000

RP/0/RP0/CPU0:h_N1(config-l2vpn-pwc-mpls)#exi
RP/0/RP0/CPU0:h_N1(config-l2vpn-pwc)#exi
RP/0/RP0/CPU0:h_N1(config-l2vpn)#
RP/0/RP0/CPU0:h_N1(config-l2vpn)#xconnect group EVPN_VPWS
RP/0/RP0/CPU0:h_N1(config-l2vpn-xc)#p2p EVPN_1
RP/0/RP0/CPU0:h_N1(config-l2vpn-xc-p2p)#interface GigabitEthernet 0/0/0/1.10
RP/0/RP0/CPU0:h_N1(config-l2vpn-xc-p2p)#neighbor evpn evi 1010 target 60 sourc$
RP/0/RP0/CPU0:h_N1(config-l2vpn-xc-p2p-pw)#?
  pw-class            PW class template name to use
RP/0/RP0/CPU0:h_N1(config-l2vpn-xc-p2p-pw)#pw-class ?
  WORD  Pseudowire-class name
RP/0/RP0/CPU0:h_N1(config-l2vpn-xc-p2p-pw)#pw-class PW60000
RP/0/RP0/CPU0:h_N1(config-l2vpn-xc-p2p-pw)#show 
Sun May 28 16:03:00.598 UTC
l2vpn
 xconnect group EVPN_VPWS
  p2p EVPN_1
   neighbor evpn evi 1010 target 60 source 10
    pw-class PW60000
   !
  !
 !
!

RP/0/RP0/CPU0:h_N1(config-l2vpn-xc-p2p-pw)#commit 
Sun May 28 16:03:16.166 UTC
RP/0/RP0/CPU0:h_N1(config-l2vpn-xc-p2p-pw)#

5. 検証

5.1 fallback enabled 検証

① SR-TE Prefered path を定義する前にはなかった Preferred path Active と言う行が出現します。

    RP/0/RP0/CPU0:h_N1#show l2vpn xconnect detail 
    Sun May 28 23:26:41.929 UTC
    
    Group EVPN_VPWS, XC EVPN_1, state is up; Interworking none
      AC: GigabitEthernet0/0/0/1.10, state is up
        Type VLAN; Num Ranges: 1
        Rewrite Tags: []
        VLAN ranges: [10, 10]
        MTU 1504; XC ID 0x2; interworking none
        Statistics:
          packets: received 10113, sent 5077
          bytes: received 67544, sent 596810
          drops: illegal VLAN 0, illegal length 0
★1   EVPN: neighbor 6.6.6.6, PW ID: evi 1010, ac-id 60, state is up ( established )
        XC ID 0xa0000003
        Encapsulation MPLS
        Encap type Ethernet, control word disabled
        Sequencing not set
★2     Preferred path Active : SR TE srte_c_60000_ep_6.6.6.6 (BSID:61000, IFH:0x3c), Statically configured, fallback enabled
        Ignore MTU mismatch: Enabled
        Transmit MTU zero: Enabled
        Tunnel : Up
    
          EVPN         Local                          Remote                        
          ------------ ------------------------------ -----------------------------
          Label        24004                          24004                         
          MTU          1518                           unknown                       
          Control word disabled                       disabled                      
          AC ID        10                             60                            
          EVPN type    Ethernet                       Ethernet                      
    
          ------------ ------------------------------ -----------------------------
        Create time: 21/05/2023 06:33:56 (1w0d ago)
        Last time status changed: 28/05/2023 23:25:57 (00:00:44 ago)
        Statistics:
          packets: received 5077, sent 10113
          bytes: received 596810, sent 67544
    RP/0/RP0/CPU0:h_N1#

★1 EVPN VPWS state is up ( established ) UPしています。
★2 Default で fallback enabled です。つまり、SR-TE が仮に down しても IGP routing によって通信を継続します。
→ SR-TE down を fallback するという option 定義です。

② SR TE srte_c_60000_ep_6.6.6.6 の転送状況を確認します。

    RP/0/RP0/CPU0:h_N1#show segment-routing traffic-eng forwarding policy detail 
    Sun May 28 23:36:52.736 UTC
    
    SR-TE Policy Forwarding database
    --------------------------------
    
    Color: 60000, End-point: 6.6.6.6
★1   Name: srte_c_60000_ep_6.6.6.6
      Binding SID: 61000
★2   Active LSP:
        Candidate path:
          Preference: 100 (configuration)
          Name: LIGHTNING
★3     Local label: 1001007
        Segment lists:
          SL[0]:
            Name: EVPN_VPWS_PREFER
            Switched Packets/Bytes: 14856/1811022
              [MPLS -> MPLS]: 14856/1811022
            Paths:
              Path[0]:
                Outgoing Label: 16003
                Outgoing Interfaces: GigabitEthernet0/0/0/0
                Next Hop: 10.1.2.2
                Switched Packets/Bytes: 14856/1811022
                  [MPLS -> MPLS]: 14856/1811022
                FRR Pure Backup: No
                ECMP/LFA Backup: No
                Internal Recursive Label: Unlabelled (recursive)
★4             Label Stack (Top -> Bottom): { 16003, 16004, 16005, 16006 }
                Path-id: 1, Weight: 64
    
      Policy Packets/Bytes Switched: 23417/2943792
    
    RP/0/RP0/CPU0:h_N1#

★1 SR-TE のポリシー名は、srte_c_60000_ep_6.6.6.6
★2 SR-TE は有効です。
★3 Local label: 1001007 ★4 Label Stack している状況が確認できます。

③ SR-TE は UP/UP しています。

   RP/0/RP0/CPU0:h_N1#show segment-routing traffic-eng policy detail 
   Sun May 28 23:48:28.366 UTC
   
   SR-TE policy database
   ---------------------
   
★ Color: 60000, End-point: 6.6.6.6
     Name: srte_c_60000_ep_6.6.6.6
     Status:
★     Admin: up  Operational: up for 00:22:30 (since May 28 23:25:57.433)
     Candidate-paths:
       Preference: 100 (configuration) (active)
         Name: LIGHTNING
         Requested BSID: 61000
           Protection Type: protected-preferred
           Maximum SID Depth: 10 
★       Explicit: segment-list EVPN_VPWS_PREFER (valid)
           Weight: 1, Metric Type: TE
             16002
             16003
             16004
             16005
             16006
     LSPs:
       LSP[0]:
         LSP-ID: 3 policy ID: 5 (active)
         Local label: 1001007
         State: Programmed
         Binding SID: 61000
     Attributes:
       Binding SID: 61000
       Forward Class: Not Configured
       Steering labeled-services disabled: no
       Steering BGP disabled: no
       IPv6 caps enable: yes
       Invalidation drop enabled: no
   
   RP/0/RP0/CPU0:h_N1#

Admin: up Operational: up で、Explicit: segment-list EVPN_VPWS_PREFER (valid) 想定通り steering しています。

④ Provider NW内の SR-TE を traceroute で確認します。

RP/0/RP0/CPU0:h_N1#traceroute 6.6.6.6 source loopback 0                      
Sun May 28 23:42:38.955 UTC

Type escape sequence to abort.
Tracing the route to 6.6.6.6

 1  10.1.2.2 [MPLS: Labels 16003/16004/16005/16006 Exp 0] 12 msec  4 msec  4 msec 
 2  10.2.3.3 [MPLS: Labels 16004/16005/16006 Exp 0] 6 msec  4 msec  4 msec 
 3  10.3.4.4 [MPLS: Labels 16005/16006 Exp 0] 7 msec  4 msec  4 msec 
 4  10.4.5.5 [MPLS: Label 16006 Exp 0] 8 msec  4 msec  4 msec 
 5  10.5.6.6 12 msec  *  6 msec 
RP/0/RP0/CPU0:h_N1#

L2VPN なので CEルータ同士の疎通確認ではラベルスタックが確認できませんが、↑のようにトラフィックが流れます。

⑤ 当然ですが、CEルータ同士の疎通できています。

CE1#ping 192.0.2.200 repeat 40
Type escape sequence to abort.
Sending 40, 100-byte ICMP Echos to 192.0.2.200, timeout is 2 seconds:
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Success rate is 100 percent (40/40), round-trip min/avg/max = 2/3/8 ms
CE1#

⑥ ここで、SR-TE を DOWN させます。Explicit Path の最初の SID が Down すると、SR-TE が DOWN します。手っ取り早いのは h_N2 の Loopback 0 を shutdown することです。詳しくは、過去のブログをご参照ください。
chimay-wh.hatenablog.com

RP/0/RP0/CPU0:h_N2#con 
Sun May 28 23:57:24.318 UTC
RP/0/RP0/CPU0:h_N2(config)#int lo0
RP/0/RP0/CPU0:h_N2(config-if)#shutdown 
RP/0/RP0/CPU0:h_N2(config-if)#commit 
Sun May 28 23:57:34.816 UTC
RP/0/RP0/CPU0:h_N2(config-if)#

⑦ SR-TE が DOWN します。

   RP/0/RP0/CPU0:h_N1#show segment-routing traffic-eng policy detail 
   Sun May 28 23:59:17.625 UTC
   
   SR-TE policy database
   ---------------------
   
★ Color: 60000, End-point: 6.6.6.6
     Name: srte_c_60000_ep_6.6.6.6
     Status:
★     Admin: up  Operational: down for 00:01:42 (since May 28 23:57:35.059)
     Candidate-paths:
       Preference: 100 (configuration)
         Name: LIGHTNING
         Requested BSID: 61000
           Protection Type: protected-preferred
           Maximum SID Depth: 10 
★       Explicit: segment-list EVPN_VPWS_PREFER (invalid)
         Last error: unresolved first label (16002)
           Weight: 1, Metric Type: TE
     Attributes:
       Forward Class: 0
       Steering labeled-services disabled: no
       Steering BGP disabled: no
       IPv6 caps enable: no
       Invalidation drop enabled: no
             
   RP/0/RP0/CPU0:h_N1#

Admin: up Operational: down となり、segment-list EVPN_VPWS_PREFER (invalid) となります。

⑧ しかし、EVPN VPWS は、SR-TE を使わずに regular IGP path を使って state is up ( established ) を継続します。

   RP/0/RP0/CPU0:h_N1#show l2vpn xconnect detail 
   Mon May 29 00:08:19.514 UTC
   
   Group EVPN_VPWS, XC EVPN_1, state is up; Interworking none
     AC: GigabitEthernet0/0/0/1.10, state is up
       Type VLAN; Num Ranges: 1
       Rewrite Tags: []
       VLAN ranges: [10, 10]
       MTU 1504; XC ID 0x2; interworking none
       Statistics:
         packets: received 9030, sent 15901
         bytes: received 1370146, sent 1874042
         drops: illegal VLAN 0, illegal length 0
★   EVPN: neighbor 6.6.6.6, PW ID: evi 1010, ac-id 60, state is up ( established )
       XC ID 0xa0000003
       Encapsulation MPLS
       Encap type Ethernet, control word disabled
       Sequencing not set
       Preferred path Active : SR TE srte_c_60000_ep_6.6.6.6 (BSID:None, IFH:0x3c), Statically configured, fallback enabled
       Ignore MTU mismatch: Enabled
       Transmit MTU zero: Enabled
       Tunnel : Up
   
         EVPN         Local                          Remote                        
         ------------ ------------------------------ -----------------------------
         Label        24004                          24004                         
         MTU          1518                           unknown                       
         Control word disabled                       disabled                      
         AC ID        10                             60                            
         EVPN type    Ethernet                       Ethernet                      
   
         ------------ ------------------------------ -----------------------------
       Create time: 21/05/2023 06:33:56 (1w0d ago)
       Last time status changed: 28/05/2023 23:25:57 (00:42:21 ago)
       Statistics:
         packets: received 15901, sent 9030
         bytes: received 1874042, sent 1370146
   RP/0/RP0/CPU0:h_N1#

SR-TE の転送状況を確認すると、SR-TE を使っていないことは明白です。

   RP/0/RP0/CPU0:h_N1#show segment-routing traffic-eng forwarding policy detail 
   Mon May 29 00:15:18.715 UTC
   
   SR-TE Policy Forwarding database
   --------------------------------
   
   Color: 60000, End-point: 6.6.6.6
     Name: srte_c_60000_ep_6.6.6.6
   
     Policy Packets/Bytes Switched: 35199/4426854
   
   RP/0/RP0/CPU0:h_N1#

⑨ Provider NW内の SR-TE を traceroute で確認します。

RP/0/RP0/CPU0:h_N1#traceroute 6.6.6.6 source loopback 0
Mon May 29 00:17:30.554 UTC

Type escape sequence to abort.
Tracing the route to 6.6.6.6

 1  10.1.2.2 [MPLS: Label 16006 Exp 0] 10 msec 
    10.1.3.3 8 msec  3 msec 
 2  10.3.5.5 [MPLS: Label 16006 Exp 0] 7 msec 
    10.3.4.4 6 msec 
    10.3.5.5 4 msec 
 3  10.5.6.6 9 msec  * 
    10.4.6.6 5 msec 
RP/0/RP0/CPU0:h_N1#

⑩ 当然ですが、CEルータ同士の疎通できています。

CE1#ping 192.0.2.200 repeat 40
Type escape sequence to abort.
Sending 40, 100-byte ICMP Echos to 192.0.2.200, timeout is 2 seconds:
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Success rate is 100 percent (40/40), round-trip min/avg/max = 4/5/7 ms
CE1#

これが fallback enabled（Default）の動作です。SR-TE が DOWN しても、regular IGP path を使って EVPN VPWS を継続利用できるようになります。

5.2 fallback disable 検証

ここまでの状況を簡単に言うと、SR-TE が DOWN しています。しかし、EVPN VPWS は preferred-path の fallback option によって通信を継続させています。ここで、fallback option を disable にするとどうなるのかを検証します。

① fallback option を disable にします。

    RP/0/RP0/CPU0:h_N1#conf
    Mon May 29 00:22:57.885 UTC
    RP/0/RP0/CPU0:h_N1(config)#l2vpn 
    RP/0/RP0/CPU0:h_N1(config-l2vpn)#pw-class PW60000
    RP/0/RP0/CPU0:h_N1(config-l2vpn-pwc)#encapsulation mpls 
★  RP/0/RP0/CPU0:h_N1(config-l2vpn-pwc-mpls)#$srte_c_60000_ep_6.6.6.6 ?           
★    fallback  Fallback option for preferred path
★    <cr>      
★  RP/0/RP0/CPU0:h_N1(config-l2vpn-pwc-mpls)#$srte_c_60000_ep_6.6.6.6 fallback ?
★    disable  Disable fallback for preferred path
★  RP/0/RP0/CPU0:h_N1(config-l2vpn-pwc-mpls)#preferred-path sr-te policy srte_c_6$
    RP/0/RP0/CPU0:h_N1(config-l2vpn-pwc-mpls)#show 
    Mon May 29 00:26:53.780 UTC
    l2vpn
     pw-class PW60000
      encapsulation mpls
       preferred-path sr-te policy srte_c_60000_ep_6.6.6.6 fallback disable
      !
     !
    !
    
    RP/0/RP0/CPU0:h_N1(config-l2vpn-pwc-mpls)#

② VPWS の詳細を確認します。

   RP/0/RP0/CPU0:h_N1#show l2vpn xconnect detail 
   Mon May 29 00:31:21.114 UTC
   
   Group EVPN_VPWS, XC EVPN_1, state is down; Interworking none
     AC: GigabitEthernet0/0/0/1.10, state is up
       Type VLAN; Num Ranges: 1
       Rewrite Tags: []
       VLAN ranges: [10, 10]
       MTU 1504; XC ID 0x2; interworking none
       Statistics:
         packets: received 9030, sent 15901
         bytes: received 1370146, sent 1874042
         drops: illegal VLAN 0, illegal length 0
★   EVPN: neighbor 6.6.6.6, PW ID: evi 1010, ac-id 60, state is down ( local ready )
       XC ID 0xa0000003
       Encapsulation MPLS
       Encap type Ethernet, control word disabled
       Sequencing not set
       Preferred path Active : SR TE srte_c_60000_ep_6.6.6.6 (BSID:None, IFH:0x3c), Statically configured, fallback disabled
       Ignore MTU mismatch: Enabled
       Transmit MTU zero: Enabled
       Tunnel : Down
   
         EVPN         Local                          Remote                        
         ------------ ------------------------------ -----------------------------
         Label        24004                          24004                         
         MTU          1518                           unknown                       
         Control word disabled                       disabled                      
         AC ID        10                             60                            
         EVPN type    Ethernet                       Ethernet                      
   
         ------------ ------------------------------ -----------------------------
       Create time: 21/05/2023 06:33:56 (1w0d ago)
       Last time status changed: 29/05/2023 00:30:59 (00:00:21 ago)
       Statistics:
         packets: received 15901, sent 9030
         bytes: received 1874042, sent 1370146
   RP/0/RP0/CPU0:h_N1#

state is down ( local ready ) となり、EVPN VPWS も SR-TE と同様に DOWN します。

③ Provider NW内の SR-TE を traceroute で確認します。

RP/0/RP0/CPU0:h_N1#traceroute 6.6.6.6 source loopback 0               
Mon May 29 00:36:22.736 UTC

Type escape sequence to abort.
Tracing the route to 6.6.6.6

 1  10.1.2.2 [MPLS: Label 16006 Exp 0] 9 msec  3 msec 
    10.1.3.3 6 msec 
 2  10.2.4.4 [MPLS: Label 16006 Exp 0] 5 msec  3 msec  4 msec 
 3  10.4.6.6 9 msec 
    10.5.6.6 5 msec  * 
RP/0/RP0/CPU0:h_N1#

regular IGP path が生きているため Head-end から End-point との通信は可能な状態です。

④ Provider NW 内は疎通可能な状態ですが、SR-TE が DOWN しており更に VPWS の preferred-path の fallback option が disable になっているため SR-TE の fallback が働かないため、CEルータ同士は疎通ができなくなります。

CE1#ping 192.0.2.200 repeat 40
Type escape sequence to abort.
Sending 40, 100-byte ICMP Echos to 192.0.2.200, timeout is 2 seconds:
........................................
Success rate is 0 percent (0/40)
CE1#