SR-TE & Link Color Constraints 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. Link Color Constraints
- 2. Topology
- 3. Config
- 4．下準備（各種メトリックの仕込み）
- 5. SR-TE の実装
- 5.2 Head-End(h_N1)
- 6. 検証
- 7. 検証から分かったこと
- 8. 参考
1. Link Color Constraints
リンクを論理的に色分けし、色に応じた経路を動的に生成する SR-TE
2. Topology
3. Config
◆h_N1（Head-End：exclude-any：RED & GREEN ／ metric type：TE）
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
!
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
shutdown
!
interface GigabitEthernet0/0/0/2
ipv4 address 10.1.3.1 255.255.255.0
!
router isis 1
apply-group CCIE-ISIS
net 49.0001.0000.0000.0001.00
distribute link-state level 2
address-family ipv4 unicast
mpls traffic-eng level-2-only
mpls traffic-eng router-id Loopback0
!
interface Loopback0
address-family ipv4 unicast
prefix-sid index 1
!
!
interface GigabitEthernet0/0/0/0
!
interface GigabitEthernet0/0/0/2
!
!
mpls oam
!
segment-routing
traffic-eng
interface GigabitEthernet0/0/0/0
affinity
name BULE
!
!
interface GigabitEthernet0/0/0/2
affinity
name BLUE
name GREEN
!
!
policy LINK_COLOR_CONSTRAINS_POLICY
binding-sid mpls 24365
color 6666 end-point ipv4 6.6.6.6
autoroute
include ipv4 6.6.6.6/32
!
candidate-paths
preference 100
dynamic
metric
type te
!
!
constraints
affinity
exclude-any
name RED
name GREEN
!
!
!
!
!
!
affinity-map
name RED bit-position 10
name BULE bit-position 20
name GREEN bit-position 30
!
!
!
end
◆h_N1（Head-End：exclude-any：RED & GREEN ／ metric type：IGP）
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
!
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
shutdown
!
interface GigabitEthernet0/0/0/2
ipv4 address 10.1.3.1 255.255.255.0
!
router isis 1
apply-group CCIE-ISIS
net 49.0001.0000.0000.0001.00
distribute link-state level 2
address-family ipv4 unicast
mpls traffic-eng level-2-only
mpls traffic-eng router-id Loopback0
!
interface Loopback0
address-family ipv4 unicast
prefix-sid index 1
!
!
interface GigabitEthernet0/0/0/0
!
interface GigabitEthernet0/0/0/2
!
!
mpls oam
!
segment-routing
traffic-eng
interface GigabitEthernet0/0/0/0
affinity
name BULE
!
!
interface GigabitEthernet0/0/0/2
affinity
name BLUE
name GREEN
!
!
policy LINK_COLOR_CONSTRAINS_POLICY
binding-sid mpls 24365
color 6666 end-point ipv4 6.6.6.6
autoroute
include ipv4 6.6.6.6/32
!
candidate-paths
preference 100
dynamic
metric
type igp
!
!
constraints
affinity
exclude-any
name RED
name GREEN
!
!
!
!
!
!
affinity-map
name RED bit-position 10
name BULE bit-position 20
name GREEN bit-position 30
!
!
!
end
◆h_N1（Head-End：include-all：BLUE ／ metric type：IGP）
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
!
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
no shut
!
interface GigabitEthernet0/0/0/1
shutdown
!
interface GigabitEthernet0/0/0/2
ipv4 address 10.1.3.1 255.255.255.0
no shut
!
interface GigabitEthernet0/0/0/3
shutdown
!
interface GigabitEthernet0/0/0/4
shutdown
!
router isis 1
apply-group CCIE-ISIS
net 49.0001.0000.0000.0001.00
distribute link-state level 2
address-family ipv4 unicast
mpls traffic-eng level-2-only
mpls traffic-eng router-id Loopback0
!
interface Loopback0
address-family ipv4 unicast
prefix-sid index 1
!
!
interface GigabitEthernet0/0/0/0
!
interface GigabitEthernet0/0/0/2
!
!
mpls oam
!
segment-routing
traffic-eng
interface GigabitEthernet0/0/0/0
affinity
name BULE
!
!
interface GigabitEthernet0/0/0/2
affinity
name BLUE
name GREEN
!
!
policy LINK_COLOR_CONSTRAINS_POLICY
binding-sid mpls 24365
color 6666 end-point ipv4 6.6.6.6
autoroute
include ipv4 6.6.6.6/32
!
candidate-paths
preference 100
dynamic
metric
type igp
!
!
constraints
affinity
include-all
name BLUE
!
!
!
!
!
!
affinity-map
name RED bit-position 10
name BULE bit-position 20
name GREEN bit-position 30
!
!
!
end
◆h_N1（Head-End：include-any：BLUE & RED ／ metric type：TE）
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
!
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
shutdown
!
interface GigabitEthernet0/0/0/2
ipv4 address 10.1.3.1 255.255.255.0
!
router isis 1
apply-group CCIE-ISIS
net 49.0001.0000.0000.0001.00
distribute link-state level 2
address-family ipv4 unicast
mpls traffic-eng level-2-only
mpls traffic-eng router-id Loopback0
!
interface Loopback0
address-family ipv4 unicast
prefix-sid index 1
!
!
interface GigabitEthernet0/0/0/0
!
interface GigabitEthernet0/0/0/2
!
!
mpls oam
!
segment-routing
traffic-eng
interface GigabitEthernet0/0/0/0
affinity
name BULE
!
!
interface GigabitEthernet0/0/0/2
affinity
name BLUE
name GREEN
!
!
policy LINK_COLOR_CONSTRAINS_POLICY
binding-sid mpls 24365
color 6666 end-point ipv4 6.6.6.6
autoroute
include ipv4 6.6.6.6/32
!
candidate-paths
preference 100
dynamic
metric
type te
!
!
constraints
affinity
include-any
name RED
name BLUE
!
!
!
!
!
!
affinity-map
name RED bit-position 10
name BULE bit-position 20
name GREEN bit-position 30
!
!
!
end
h_N2（metric変更）
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
mpls traffic-eng level-2-only
mpls traffic-eng router-id Loopback0
!
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
address-family ipv4 unicast
metric 200
!
!
!
mpls oam
!
segment-routing
traffic-eng
interface GigabitEthernet0/0/0/0
affinity
name BLUE
!
!
interface GigabitEthernet0/0/0/1
affinity
name BLUE
!
!
interface GigabitEthernet0/0/0/2
affinity
name BLUE
!
metric 1000
!
affinity-map
name RED bit-position 10
name BLUE bit-position 20
name GREEN bit-position 30
!
!
!
end
h_N3（metric変更）
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
mpls traffic-eng level-2-only
mpls traffic-eng router-id Loopback0
!
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
address-family ipv4 unicast
metric 2000
!
!
!
mpls oam
!
segment-routing
traffic-eng
interface GigabitEthernet0/0/0/0
affinity
name BLUE
name GREEN
!
!
interface GigabitEthernet0/0/0/1
affinity
name BLUE
!
!
interface GigabitEthernet0/0/0/2
affinity
name RED
!
!
interface GigabitEthernet0/0/0/3
affinity
name BLUE
!
metric 100
!
affinity-map
name RED bit-position 10
name BLUE bit-position 20
name GREEN bit-position 30
!
!
!
end
h_N4（metric変更）
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
mpls traffic-eng level-2-only
mpls traffic-eng router-id Loopback0
!
interface Loopback0
prefix-attributes anycast
address-family ipv4 unicast
prefix-sid index 4
!
!
interface GigabitEthernet0/0/0/0
address-family ipv4 unicast
metric 200
!
!
interface GigabitEthernet0/0/0/1
!
interface GigabitEthernet0/0/0/2
!
interface GigabitEthernet0/0/0/3
!
!
mpls oam
!
segment-routing
traffic-eng
interface GigabitEthernet0/0/0/0
affinity
name BLUE
!
metric 1000
!
interface GigabitEthernet0/0/0/1
affinity
name BLUE
name GREEN
!
!
interface GigabitEthernet0/0/0/2
affinity
name BLUE
!
!
interface GigabitEthernet0/0/0/3
affinity
name BLUE
!
!
affinity-map
name RED bit-position 10
name BLUE bit-position 20
name GREEN bit-position 30
!
!
!
end
h_N5
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
mpls traffic-eng level-2-only
mpls traffic-eng router-id Loopback0
!
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
!
segment-routing
traffic-eng
interface GigabitEthernet0/0/0/0
affinity
name RED
!
!
interface GigabitEthernet0/0/0/1
affinity
name BLUE
name GREEN
!
!
interface GigabitEthernet0/0/0/2
affinity
name BLUE
!
!
affinity-map
name RED bit-position 10
name BLUE bit-position 20
name GREEN bit-position 30
!
!
!
end
h_N6
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
!
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
shutdown
!
interface GigabitEthernet0/0/0/2
ipv4 address 10.5.6.6 255.255.255.0
!
router isis 1
apply-group CCIE-ISIS
net 49.0001.0000.0000.0006.00
address-family ipv4 unicast
mpls traffic-eng level-2-only
mpls traffic-eng router-id Loopback0
!
interface Loopback0
address-family ipv4 unicast
prefix-sid index 6
!
!
interface GigabitEthernet0/0/0/0
!
interface GigabitEthernet0/0/0/2
!
!
mpls oam
!
segment-routing
traffic-eng
interface GigabitEthernet0/0/0/0
affinity
name BLUE
!
!
interface GigabitEthernet0/0/0/2
affinity
name BLUE
!
!
affinity-map
name RED bit-position 10
name BLUE bit-position 20
name GREEN bit-position 30
!
!
!
end
4．下準備（各種メトリックの仕込み）
4.1 IGP（Default 10）
IGP で interface を指定して定義します。
e.g. h_N2's GigabitEthernet0/0/0/2 で IGP（ISIS）のメトリックを定義
RP/0/RP0/CPU0:h_N2(config)#router isis 1 RP/0/RP0/CPU0:h_N2(config-isis)#interface gigabitEthernet 0/0/0/2 RP/0/RP0/CPU0:h_N2(config-isis-if)#address-family ipv4 unicast RP/0/RP0/CPU0:h_N2(config-isis-if-af)#metric 200 RP/0/RP0/CPU0:h_N2(config-isis-if-af)# RP/0/RP0/CPU0:h_N2(config-isis-if-af)#commit
4.2 Traffic-engineering（TE：Default 10）
Segment Routing の Traffic-engineering で interface を指定して定義します。
e.g. h_N2's GigabitEthernet0/0/0/2 で TE のメトリックを定義
RP/0/RP0/CPU0:h_N2(config)#? segment-routing Segment Routing RP/0/RP0/CPU0:h_N2(config)#segment-routing RP/0/RP0/CPU0:h_N2(config-sr)#? traffic-eng Segment Routing Traffic Engineering RP/0/RP0/CPU0:h_N2(config-sr)#traffic-eng RP/0/RP0/CPU0:h_N2(config-sr-te)#? interface Enable SR-TE on an interface(cisco-support) RP/0/RP0/CPU0:h_N2(config-sr-te)#interface gigabitEthernet 0/0/0/2 RP/0/RP0/CPU0:h_N2(config-sr-if)#? metric Interface TE metric configuration RP/0/RP0/CPU0:h_N2(config-sr-if)#metric 1000 RP/0/RP0/CPU0:h_N2(config-sr-if)# RP/0/RP0/CPU0:h_N2(config-sr-if)#show Sun Apr 2 09:15:48.466 UTC segment-routing traffic-eng interface GigabitEthernet0/0/0/2 metric 1000 ! ! ! RP/0/RP0/CPU0:h_N2(config-sr-if)#
残りのノードもトポロジ図で指定した通りに定義します。
5. SR-TE の実装
実装の流れは、①全ノードでSegment Routing の Traffic-engineering を有効にしてから ② Link Color を定義します。③ Head-End で LSDBの情報をSR-TE DBに投入します。 また、④Head-End で SR-TE のポリシーを定義します。 ⑤最後に経路(Candidate-paths)のメトリックを選択し、⑥どの色を通過許可するかの制約事項を定義します。
5.1 全ノード共通
5.1.1 SR-TE有効化
①IGPでSegment Routing を有効にします。
忘れずに Loopback0 で prefix-sid index X を有効化します。
router isis '.*'
net 49.0001.0000.0000.000X.00
address-family ipv4 unicast
metric-style wide
segment-routing mpls
!
interface Loopback 0
address-family ipv4 unicast
prefix-sid index X
!
!
!
②IGP で Traffic-engineering 有効にします。 ISIS の場合、IGP のレベルと TE のレベルを合わせます。今回の場合は、level-2-only です。
RP/0/RP0/CPU0:h_N2(config)#router isis 1 RP/0/RP0/CPU0:h_N2(config-isis)#address-family ipv4 unicast RP/0/RP0/CPU0:h_N2(config-isis-af)#? mpls Configure MPLS routing protocol parameters RP/0/RP0/CPU0:h_N2(config-isis-af)#mpls ? traffic-eng Routing protocol commands for MPLS Traffic Engineering RP/0/RP0/CPU0:h_N2(config-isis-af)#mpls traffic-eng ? level-2-only Enable mpls traffic-eng at level 2 RP/0/RP0/CPU0:h_N2(config-isis-af)#mpls traffic-eng level-2-only RP/0/RP0/CPU0:h_N2(config-isis-af)#mpls ? traffic-eng Routing protocol commands for MPLS Traffic Engineering RP/0/RP0/CPU0:h_N2(config-isis-af)#mpls traffic-eng ? router-id Traffic Engineering stable IP address for system RP/0/RP0/CPU0:h_N2(config-isis-af)#mpls traffic-eng router-id ? Loopback Loopback interface(s) | short name is Lo RP/0/RP0/CPU0:h_N2(config-isis-af)#mpls traffic-eng router-id Loopback 0 RP/0/RP0/CPU0:h_N2(config-isis-af)#show Sat Mar 25 12:43:39.055 UTC router isis 1 address-family ipv4 unicast mpls traffic-eng level-2-only mpls traffic-eng router-id Loopback0 ! ! RP/0/RP0/CPU0:h_N2(config-isis-af)#
③ グローバルで Segment Routing の Traffic-engineering 有効にします。
RP/0/RP0/CPU0:h_N2(config)#? segment-routing Segment Routing RP/0/RP0/CPU0:h_N2(config)#segment-routing ? traffic-eng Segment Routing Traffic Engineering RP/0/RP0/CPU0:h_N2(config)#segment-routing traffic-eng RP/0/RP0/CPU0:h_N2(config-sr-te)# RP/0/RP0/CPU0:h_N2(config-sr-te)#show Sat Mar 25 12:50:31.803 UTC segment-routing traffic-eng ! ! RP/0/RP0/CPU0:h_N2(config-sr-te)#
5.1.2Link Color定義
①先ずリンクの論理カラーを定義します。bit-position は任意の数字で良いですが、ドメインの全ノードで統一する必要があります。
RP/0/RP0/CPU0:h_N1(config)#segment-routing traffic-eng RP/0/RP0/CPU0:h_N1(config-sr-te)#? affinity-map Affinity map configuration RP/0/RP0/CPU0:h_N1(config-sr-te)#affinity-map RP/0/RP0/CPU0:h_N1(config-sr-te-affinity-map)#? name Affinity name RP/0/RP0/CPU0:h_N1(config-sr-te-affinity-map)#name ? WORD Affinity color name RP/0/RP0/CPU0:h_N1(config-sr-te-affinity-map)#name RED ? bit-position Bit Position for the mapped affinity RP/0/RP0/CPU0:h_N1(config-sr-te-affinity-map)#name RED bit-position ? <0-255> Affinity attribute bit position RP/0/RP0/CPU0:h_N1(config-sr-te-affinity-map)#name RED bit-position 10 ? <cr> RP/0/RP0/CPU0:h_N1(config-sr-te-affinity-map)#name RED bit-position 10 RP/0/RP0/CPU0:h_N1(config-sr-te-affinity-map)#name BULE bit-position 20 RP/0/RP0/CPU0:h_N1(config-sr-te-affinity-map)#name GREEN bit-position 30 RP/0/RP0/CPU0:h_N1(config-sr-te-affinity-map)# RP/0/RP0/CPU0:h_N1(config-sr-te-affinity-map)#show Sun Apr 2 09:22:11.691 UTC segment-routing traffic-eng affinity-map name RED bit-position 10 name BULE bit-position 20 name GREEN bit-position 30 ! ! ! RP/0/RP0/CPU0:h_N1(config-sr-te-affinity-map)#
②それぞれのリンクに論理カラーを定義します。1リンクに複数のカラーを定義することも可能です。
RP/0/RP0/CPU0:h_N1(config)#segment-routing traffic-eng
RP/0/RP0/CPU0:h_N1(config-sr-te)#interface gigabitEthernet 0/0/0/0
RP/0/RP0/CPU0:h_N1(config-sr-if)#?
affinity Interface affinity configuration
RP/0/RP0/CPU0:h_N1(config-sr-if)#affinity
RP/0/RP0/CPU0:h_N1(config-sr-if-affinity)#?
name Affinity name
RP/0/RP0/CPU0:h_N1(config-sr-if-affinity)#name ?
RED Affinity color name
BULE Affinity color name
GREEN Affinity color name
WORD Affinity color name
RP/0/RP0/CPU0:h_N1(config-sr-if-affinity)#name BULE ?
<cr>
RP/0/RP0/CPU0:h_N1(config-sr-if-affinity)#name BULE
RP/0/RP0/CPU0:h_N1(config-sr-if-affinity)#interface gigabitEthernet 0/0/0/2
RP/0/RP0/CPU0:h_N1(config-sr-if)#affinity name BLUE
RP/0/RP0/CPU0:h_N1(config-sr-if)#affinity name GREEN
RP/0/RP0/CPU0:h_N1(config-sr-if)#
RP/0/RP0/CPU0:h_N1(config-sr-if)#show
Sun Apr 2 09:25:27.084 UTC
segment-routing
traffic-eng
interface GigabitEthernet0/0/0/2
affinity
name BLUE
name GREEN
!
!
!
!
RP/0/RP0/CPU0:h_N1(config-sr-if)#
残りのノードもトポロジ図で指定した通りに定義します。
5.2 Head-End(h_N1)
5.2.1 LSDBの情報をSR-TE DBに投入
IGP で以下のコマンドを定義します。ISIS のインターフェースレベルに合わせます。
RP/0/RP0/CPU0:h_N1(config)#router isis 1 RP/0/RP0/CPU0:h_N1(config-isis)#? distribute Distribute routing information to external services RP/0/RP0/CPU0:h_N1(config-isis)#distribute ? link-state Distribute the link-state database to external services RP/0/RP0/CPU0:h_N1(config-isis)#distribute link-state ? level Set distribution for one level only RP/0/RP0/CPU0:h_N1(config-isis)#distribute link-state level ? <1-2> Level RP/0/RP0/CPU0:h_N1(config-isis)#distribute link-state level 2 RP/0/RP0/CPU0:h_N1(config-isis)#
5.2.2 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 ：LINK_COLOR_CONSTRAINS_POLICY
b) B-SID(任意)：24365
c) color ：6666
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 LINK_COLOR_CONSTRAINS_POLICY
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 24365 ? <cr>
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 6666 ? end-point Policy endpoint RP/0/RP0/CPU0:h_N1(config-sr-te-policy)#color 6666 end-point ? ipv4 IPv4 address RP/0/RP0/CPU0:h_N1(config-sr-te-policy)#color 6666 end-point ipv4 ? A.B.C.D IPv4 endpoint address RP/0/RP0/CPU0:h_N1(config-sr-te-policy)#color 6666 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
5.2.3 Candidate-paths の定義
Candidate-paths を以下のように定義します。
a) preference ：100(大きい方が優先されます！)
b) type ：IGP（後の検証で他のタイプも確認します。）
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)#?
dynamic Dynamically allocated path
RP/0/RP0/CPU0:h_N1(config-sr-te-policy-path-pref)#dynamic ?
metric Path metric configuration
RP/0/RP0/CPU0:h_N1(config-sr-te-policy-path-pref)#dynamic
RP/0/RP0/CPU0:h_N1(config-sr-te-pp-info)#?
metric Path metric configuration
RP/0/RP0/CPU0:h_N1(config-sr-te-pp-info)#metric
RP/0/RP0/CPU0:h_N1(config-sr-te-path-metric)#type ?
te TE metric type
RP/0/RP0/CPU0:h_N1(config-sr-te-path-metric)#type te
RP/0/RP0/CPU0:h_N1(config-sr-te-path-metric)#
RP/0/RP0/CPU0:h_N1(config-sr-te-path-metric)#show
Sat Mar 25 13:10:29.595 UTC
segment-routing
traffic-eng
policy LINK_COLOR_CONSTRAINS_POLICY
binding-sid mpls 24365
color 6666 end-point ipv4 6.6.6.6
autoroute
include ipv4 6.6.6.6/32
!
candidate-paths
preference 100
dynamic
metric
type igp
!
!
!
!
!
!
!
RP/0/RP0/CPU0:h_N1(config-sr-te-path-metric)#
5.2.4 Link Color Constraints の定義
① SR-TE でトラフィックがリンクを通過する際、どの色を通過するのを許可するかの制約事項を定義します。
RP/0/RP0/CPU0:h_N1(config)#seg tra po LINK_COLOR_CONSTRAINS_POLICY can pref 100 RP/0/RP0/CPU0:h_N1(config-sr-te-policy-path-pref)#? constraints Candidate path constraints RP/0/RP0/CPU0:h_N1(config-sr-te-policy-path-pref)#constraints RP/0/RP0/CPU0:h_N1(config-sr-te-path-pref-const)#? affinity Assign affinities to path RP/0/RP0/CPU0:h_N1(config-sr-te-path-pref-const)#affinity ? exclude-any Affinity attributes to exclude - presence of at least one excludes link include-all Affinity attributes - all must be included include-any Affinity attributes - at least one must be included <cr> RP/0/RP0/CPU0:h_N1(config-sr-te-path-pref-const)#
② 3つ選択肢があります。
a) exclude-any Affinity attributes to exclude - presence of at least one excludes link
→ 指定した1つ以上のカラーを除いたものを許可します。
b) include-all Affinity attributes - all must be included
→ 指定したカラーがすべて一致する必要があります。
c) include-any Affinity attributes - at least one must be included
→ 指定した1つ以上のカラーが一致している必要があります。
詳しくは後で検証します。ここでは、a) exclude-any を選択します。
RP/0/RP0/CPU0:h_N1(config-sr-te-path-pref-const)#affinity RP/0/RP0/CPU0:h_N1(config-sr-te-path-pref-const-aff)#exclude-any RP/0/RP0/CPU0:(config-sr-te-path-pref-const-aff-rule)#? name Affinity name RP/0/RP0/CPU0:(config-sr-te-path-pref-const-aff-rule)#name ? RED Affinity color name BULE Affinity color name GREEN Affinity color name WORD Affinity color name RP/0/RP0/CPU0:(config-sr-te-path-pref-const-aff-rule)#name RED ? <cr> RP/0/RP0/CPU0:(config-sr-te-path-pref-const-aff-rule)#name RED RP/0/RP0/CPU0:(config-sr-te-path-pref-const-aff-rule)#name GREEN
③ 最初に検証する条件としては、論理カラーが RED と GREEN のリンクを除外して Dynamic SR-TE が生成される様を確認します。
policy LINK_COLOR_CONSTRAINS_POLICY
binding-sid mpls 24365
color 6666 end-point ipv4 6.6.6.6
autoroute
include ipv4 6.6.6.6/32
!
candidate-paths
preference 100
dynamic
metric
type igp
!
!
constraints
affinity
exclude-any
name RED
name GREEN
!
!
!
!
!
!
!
!
6. 検証
6.1 SR-TE 基本確認
SR-TEを定義すると新しいインターフェース(SR-TE用のLSP)が出現します。
RP/0/RP0/CPU0:h_N1#show ip interface brief | exclude una Sun Apr 2 09:50:50.758 UTC Interface IP-Address Status Protocol Vrf-Name ★srte_c_6666_ep_6.6.6.6 1.1.1.1 Up Up default Loopback0 1.1.1.1 Up Up default GigabitEthernet0/0/0/0 10.1.2.1 Up Up default GigabitEthernet0/0/0/2 10.1.3.1 Up Up default RP/0/RP0/CPU0:h_N1#
今回定義したSR-TEポリシーは、Head-End：1.1.1.1(h_N1)、color：6000、Tail-End：6.6.6.6(h_N6)です。 ルーティングにその変化が現れています。
RP/0/RP0/CPU0:h_N1#show route 6.6.6.6/32 detail
Sun Apr 2 09:52:02.957 UTC
Routing entry for 6.6.6.6/32
Known via "isis 1", distance 115, metric 40, labeled SR, label redist non FIB, type level-2
Installed Apr 2 09:30:31.882 for 00:21:31
Routing Descriptor Blocks
★ 6.6.6.6, from 6.6.6.6, via srte_c_6666_ep_6.6.6.6
Route metric is 40
Label: 0x3 (3)
Tunnel ID: None
Binding Label: 0x5f2d (24365)
Extended communities count: 0
Path id:1 Path ref count:0
NHID:0x0(Ref:0)
Route version is 0x95 (149)
Local Label: 0x3e86 (16006)
IP Precedence: Not Set
QoS Group ID: Not Set
Flow-tag: Not Set
Fwd-class: Not Set
Route Priority: RIB_PRIORITY_NON_RECURSIVE_MEDIUM (7) SVD Type RIB_SVD_TYPE_LOCAL
Download Priority 1, Download Version 1079
No advertising protos.
RP/0/RP0/CPU0:h_N1#
Head-End：1.1.1.1(h_N1)の LFIB を確認すると、 SR-TEの NEXT_HOP やTail-End、B-SID(任意)：24365も確認できます。
SR-TE（LINK_COLOR_CONSTRAINS_POLICY）
・Head-End：1.1.1.1(h_N1)
・NEXT_HOP：10.1.2.2(Gi0/0/0/0)
・B-SID ：24365
RP/0/RP0/CPU0:h_N1#show mpls forwarding Sun Apr 2 09:52:59.620 UTC Local Outgoing Prefix Outgoing Next Hop Bytes Label Label or ID Interface Switched ------ ----------- ------------------ ------------ --------------- ------------ 16002 Pop SR Pfx (idx 2) Gi0/0/0/0 10.1.2.2 0 16003 Pop SR Pfx (idx 3) Gi0/0/0/2 10.1.3.3 0 16004 16004 SR Pfx (idx 4) Gi0/0/0/2 10.1.3.3 0 16005 16005 SR Pfx (idx 5) Gi0/0/0/2 10.1.3.3 0 16006 16006 SR Pfx (idx 6) Gi0/0/0/2 10.1.3.3 0 24000 Pop SR Adj (idx 1) Gi0/0/0/2 10.1.3.3 0 24001 Pop SR Adj (idx 3) Gi0/0/0/2 10.1.3.3 0 24002 Pop SR Adj (idx 1) Gi0/0/0/0 10.1.2.2 0 24003 Pop SR Adj (idx 3) Gi0/0/0/0 10.1.2.2 0 ★24005 Pop 6.6.6.6/32 srte_c_6666_ 6.6.6.6 0 24006 Pop No ID Gi0/0/0/0 10.1.2.2 0 ★24007 16003 SR TE: 4 [TE-INT] Gi0/0/0/0 10.1.2.2 364 24008 Pop No ID Gi0/0/0/2 10.1.3.3 0 ★24365 Pop No ID srte_c_6666_ point2point 0 RP/0/RP0/CPU0:h_N1#
CEFを確認するとSR-TEで定義した内容が反映されています。他のLoopbackアドレスと見比べると分かりやすいかと思います。
SR-TEのautorouteが効いています。他のLoopbackアドレスだとNEXT_HOPがインターフェース名ですが、Head-End宛だけがSR-TEになっています。
RP/0/RP0/CPU0:h_N1#show cef
Sun Apr 2 09:54:33.596 UTC
Prefix Next Hop Interface
------------------- ------------------- ------------------
0.0.0.0/0 drop default handler
0.0.0.0/32 broadcast
1.1.1.1/32 receive Loopback0
2.2.2.2/32 10.1.2.2/32 GigabitEthernet0/0/0/0
3.3.3.3/32 10.1.3.3/32 GigabitEthernet0/0/0/2
4.4.4.4/32 10.1.3.3/32 GigabitEthernet0/0/0/2
5.5.5.5/32 10.1.3.3/32 GigabitEthernet0/0/0/2
★6.6.6.6/32 6.6.6.6/32 srte_c_6666_ep_6.6.6.6
10.1.2.0/24 attached GigabitEthernet0/0/0/0
10.1.2.0/32 broadcast GigabitEthernet0/0/0/0
10.1.2.1/32 receive GigabitEthernet0/0/0/0
10.1.2.255/32 broadcast GigabitEthernet0/0/0/0
10.1.3.0/24 attached GigabitEthernet0/0/0/2
10.1.3.0/32 broadcast GigabitEthernet0/0/0/2
10.1.3.1/32 receive GigabitEthernet0/0/0/2
10.1.3.255/32 broadcast GigabitEthernet0/0/0/2
10.2.3.0/24 10.1.2.2/32 GigabitEthernet0/0/0/0
10.1.3.3/32 GigabitEthernet0/0/0/2
10.2.4.0/24 10.1.2.2/32 GigabitEthernet0/0/0/0
10.3.4.0/24 10.1.3.3/32 GigabitEthernet0/0/0/2
10.3.5.0/24 10.1.3.3/32 GigabitEthernet0/0/0/2
10.4.5.0/24 10.1.3.3/32 GigabitEthernet0/0/0/2
10.4.6.0/24 10.1.3.3/32 GigabitEthernet0/0/0/2
10.5.6.0/24 10.1.3.3/32 GigabitEthernet0/0/0/2
127.0.0.0/8 receive
224.0.0.0/4 0.0.0.0/32
224.0.0.0/24 receive
255.255.255.255/32 broadcast
RP/0/RP0/CPU0:h_N1#
SR-TE ポリシーの情報はコマンドで確認することができます。
RP/0/RP0/CPU0:h_N1#show segment-routing traffic-eng policy
Sun Apr 2 09:55:27.281 UTC
SR-TE policy database
---------------------
Color: 6666, End-point: 6.6.6.6
★1 Name: srte_c_6666_ep_6.6.6.6
Status:
★2 Admin: up Operational: up for 00:24:55 (since Apr 2 09:30:31.714)
Candidate-paths:
Preference: 100 (configuration) (active)
★3 Name: LINK_COLOR_CONSTRAINS_POLICY
★4 Requested BSID: 24365
Constraints:
Protection Type: protected-preferred
★5 Affinity:
★5 exclude-any:
★5 GREEN
★5 RED
Maximum SID Depth: 10
★6 Dynamic (valid)
★7 Metric Type: TE, Path Accumulated Metric: 130
★8 16002 [Prefix-SID, 2.2.2.2]
★8 16003 [Prefix-SID, 3.3.3.3]
★8 24003 [Adjacency-SID, 10.3.4.3 - 10.3.4.4]
★8 16006 [Prefix-SID, 6.6.6.6]
Attributes:
Binding SID: 24365
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#
★1：Color と End-point(Head-End) が自動的にLSP名に反映されるのが特徴です。
SR-TE LSP名(Name: srte_c_6_ep_6.6.6.6)から、Color: 6000, End-point: 6.6.6.6であることが分かります。
★2：SR-TEが有効な状態を示しています。(Admin: up Operational: up)
★3：SR-TE ポリシーは、LINK_COLOR_CONSTRAINS_POLICY であることが分かります。
★4：このSR-TEに紐づけられているBinding SIDは、 24365 であることが分かります。
★5：論理リンクの GREEN と RED を通過しないTEであることが分かります。
★6：有効な Dynamic SR-TE であることが分かります。
★7：Dynamic SR-TE は TE のメトリックで計算して 最短経路が 130 であることが分かります。
★8：SID-list（今回は４つのSID）が確認できます。
tracerouteを実行すると、SR-TE の経路が分かります。
RP/0/RP0/CPU0:h_N1#traceroute 6.6.6.6 source 1.1.1.1 Sun Apr 2 10:07:46.695 UTC Type escape sequence to abort. Tracing the route to 6.6.6.6 1 10.1.2.2 [MPLS: Labels 16003/24003/16006 Exp 0] 11 msec 3 msec 3 msec 2 10.2.3.3 [MPLS: Labels 24003/16006 Exp 0] 6 msec 4 msec 3 msec 3 10.3.4.4 [MPLS: Label 16006 Exp 0] 7 msec 3 msec 3 msec 4 10.4.6.6 16 msec * 16 msec RP/0/RP0/CPU0:h_N1#
除外リンク（RED & GREEN）を経由しない、かつ TE のメトリックが最小となる経路の SR-TE が動的に生成されていることが分かります。
次のコマンドで、SR-TE の転送状況が確認できます。
RP/0/RP0/CPU0:h_N1#show segment-routing traffic-eng forwarding policy
Sun Apr 2 10:15:43.883 UTC
SR-TE Policy Forwarding database
--------------------------------
Color: 6666, End-point: 6.6.6.6
Name: srte_c_6666_ep_6.6.6.6
Binding SID: 24365
Active LSP:
Candidate path:
Preference: 100 (configuration)
Name: LINK_COLOR_CONSTRAINS_POLICY
Local label: 24007
Segment lists:
SL[0]:
Name: dynamic
Switched Packets/Bytes: 25/700
[MPLS -> MPLS]: 25/700
Paths:
Path[0]:
Outgoing Label: 16003
Outgoing Interfaces: GigabitEthernet0/0/0/0
Next Hop: 10.1.2.2
Switched Packets/Bytes: 25/700
[MPLS -> MPLS]: 25/700
FRR Pure Backup: No
ECMP/LFA Backup: No
Internal Recursive Label: Unlabelled (recursive)
Label Stack (Top -> Bottom): { 16003, 24003, 16006 }
Policy Packets/Bytes Switched: 51/1428
RP/0/RP0/CPU0:h_N1#
6.2 metric type：igp（exclude-any： RED and GREEN ）
ここで、metric type：igp に変更します。
RP/0/RP0/CPU0:h_N1(config)#
RP/0/RP0/CPU0:h_N1(config)#seg tr policy LINK_COLOR_CONSTRAINS_POLICY can pref$
RP/0/RP0/CPU0:h_N1(config-sr-te-path-metric)#type igp
RP/0/RP0/CPU0:h_N1(config-sr-te-path-metric)#show
Sun Apr 2 10:17:55.796 UTC
segment-routing
traffic-eng
policy LINK_COLOR_CONSTRAINS_POLICY
candidate-paths
preference 100
dynamic
metric
type igp
!
!
!
!
!
!
!
RP/0/RP0/CPU0:h_N1(config-sr-te-path-metric)#
インターフェースの状態、ルーティングテーブル、CEFは変化がありませんが、LFIBに変化が現れます。
RP/0/RP0/CPU0:h_N1#show mpls forwarding Sun Apr 2 10:19:45.505 UTC Local Outgoing Prefix Outgoing Next Hop Bytes Label Label or ID Interface Switched ------ ----------- ------------------ ------------ --------------- ------------ 16002 Pop SR Pfx (idx 2) Gi0/0/0/0 10.1.2.2 0 16003 Pop SR Pfx (idx 3) Gi0/0/0/2 10.1.3.3 0 16004 16004 SR Pfx (idx 4) Gi0/0/0/2 10.1.3.3 0 16005 16005 SR Pfx (idx 5) Gi0/0/0/2 10.1.3.3 0 16006 16006 SR Pfx (idx 6) Gi0/0/0/2 10.1.3.3 0 24000 Pop SR Adj (idx 1) Gi0/0/0/2 10.1.3.3 0 24001 Pop SR Adj (idx 3) Gi0/0/0/2 10.1.3.3 0 24002 Pop SR Adj (idx 1) Gi0/0/0/0 10.1.2.2 0 24003 Pop SR Adj (idx 3) Gi0/0/0/0 10.1.2.2 0 24005 Pop 6.6.6.6/32 srte_c_6666_ 6.6.6.6 0 24006 Pop No ID Gi0/0/0/0 10.1.2.2 0 24008 Pop No ID Gi0/0/0/2 10.1.3.3 0 ★ 24009 24003 SR TE: 4 [TE-INT] Gi0/0/0/0 10.1.2.2 252 24365 Pop No ID srte_c_6666_ point2point 0 RP/0/RP0/CPU0:h_N1#
IGP のメトリック合計が最も小さい経路のみに SR-TE が動的に変化します。
SR-TE ポリシーにもその変化は現れます。
RP/0/RP0/CPU0:h_N1#show segment-routing traffic-eng policy
Sun Apr 2 10:21:28.895 UTC
SR-TE policy database
---------------------
Color: 6666, End-point: 6.6.6.6
Name: srte_c_6666_ep_6.6.6.6
Status:
Admin: up Operational: up for 00:50:57 (since Apr 2 09:30:31.714)
Candidate-paths:
Preference: 100 (configuration) (active)
Name: LINK_COLOR_CONSTRAINS_POLICY
Requested BSID: 24365
Constraints:
Protection Type: protected-preferred
Affinity:
exclude-any:
GREEN
RED
Maximum SID Depth: 10
Dynamic (valid)
★1 Metric Type: IGP, Path Accumulated Metric: 220
★2 16002 [Prefix-SID, 2.2.2.2]
★2 24003 [Adjacency-SID, 10.2.4.2 - 10.2.4.4]
★2 16006 [Prefix-SID, 6.6.6.6]
Attributes:
Binding SID: 24365
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#
★1：Dynamic SR-TE は IGP のメトリックで計算して 最短経路が 220 であることが分かります。
★2：SID-list（今回は3つのSID）が確認できます。
RP/0/RP0/CPU0:h_N1#traceroute 6.6.6.6 source 1.1.1.1 Sun Apr 2 10:23:30.644 UTC Type escape sequence to abort. Tracing the route to 6.6.6.6 1 10.1.2.2 [MPLS: Labels 24003/16006 Exp 0] 10 msec 3 msec 3 msec 2 10.2.4.4 [MPLS: Label 16006 Exp 0] 5 msec 3 msec 3 msec 3 10.4.6.6 13 msec * 5 msec RP/0/RP0/CPU0:h_N1#
除外リンク（RED & GREEN）を経由しない、かつ IGP のメトリックが最小となる経路の SR-TE が動的に生成されていることが分かります。
次のコマンドで、SR-TE の転送状況が確認できます。
RP/0/RP0/CPU0:h_N1#show segment-routing traffic-eng forwarding policy detail
Sun Apr 2 10:24:47.843 UTC
SR-TE Policy Forwarding database
--------------------------------
Color: 6666, End-point: 6.6.6.6
Name: srte_c_6666_ep_6.6.6.6
Binding SID: 24365
Active LSP:
Candidate path:
Preference: 100 (configuration)
Name: LINK_COLOR_CONSTRAINS_POLICY
Local label: 24009
Segment lists:
SL[0]:
Name: dynamic
Switched Packets/Bytes: 18/504
[MPLS -> MPLS]: 18/504
Paths:
Path[0]:
Outgoing Label: 24003
Outgoing Interfaces: GigabitEthernet0/0/0/0
Next Hop: 10.1.2.2
Switched Packets/Bytes: 18/504
[MPLS -> MPLS]: 18/504
FRR Pure Backup: No
ECMP/LFA Backup: No
Internal Recursive Label: Unlabelled (recursive)
Label Stack (Top -> Bottom): { 24003, 16006 }
Path-id: 1, Weight: 64
Policy Packets/Bytes Switched: 69/1932
RP/0/RP0/CPU0:h_N1#
”exclude-any”の使い方が分かったので、次の選択肢を検証します。
6.3 include-all：BLUE ／ metric type：IGP
指定したカラーがすべて一致するという制約条件に変更します。 h_N1 から h_N6 の経路で”include-all”として指定できるカラーは BLUE しかありません。
RP/0/RP0/CPU0:h_N1(config-sr-te-path-pref-const)#affinity ? exclude-any Affinity attributes to exclude - presence of at least one excludes link include-all Affinity attributes - all must be included include-any Affinity attributes - at least one must be included <cr> RP/0/RP0/CPU0:h_N1(config-sr-te-path-pref-const)#
ということで、”include-all：BLUE ”に変更します。
RP/0/RP0/CPU0:h_N1(config)#seg tr po LINK_COLOR_CONSTRAINS_POLICY can pref 100
RP/0/RP0/CPU0:h_N1(config-sr-te-policy-path-pref)#constraints affinity
RP/0/RP0/CPU0:h_N1(config-sr-te-path-pref-const-aff)#no exclude-any
RP/0/RP0/CPU0:h_N1(config-sr-te-path-pref-const-aff)#include-all
RP/0/RP0/CPU0:(config-sr-te-path-pref-const-aff-rule)#name BLUE
RP/0/RP0/CPU0:(config-sr-te-path-pref-const-aff-rule)#show
Sun Apr 2 10:38:43.268 UTC
segment-routing
traffic-eng
policy LINK_COLOR_CONSTRAINS_POLICY
candidate-paths
preference 100
constraints
affinity
include-all
name BLUE
!
!
!
!
!
!
!
!
RP/0/RP0/CPU0:(config-sr-te-path-pref-const-aff-rule)#
traceroute を実行してみます。
RP/0/RP0/CPU0:h_N1#traceroute 6.6.6.6 source 1.1.1.1 Sun Apr 2 12:06:11.386 UTC Type escape sequence to abort. Tracing the route to 6.6.6.6 1 10.1.3.3 [MPLS: Label 16006 Exp 0] 10 msec 4 msec 3 msec 2 10.3.5.5 [MPLS: Label 16006 Exp 0] 5 msec 3 msec 3 msec 3 10.5.6.6 8 msec * 9 msec RP/0/RP0/CPU0:h_N1#
(。´・ω・)ん? おかしい！ RED のリンクを通過しています。以下のようになることを想定していました。
許可リンク（BLUE のみ）を経由する、かつ IGP のメトリックが最小となる経路の SR-TE が動的に生成されることを想定していました。
RP/0/RP0/CPU0:h_N1#show segment-routing traffic-eng policy
Sun Apr 2 14:09:14.130 UTC
SR-TE policy database
---------------------
Color: 6666, End-point: 6.6.6.6
Name: srte_c_6666_ep_6.6.6.6
Status:
Admin: up Operational: up for 02:15:18 (since Apr 2 11:53:56.135)
Candidate-paths:
Preference: 100 (configuration) (active)
Name: LINK_COLOR_CONSTRAINS_POLICY
Requested BSID: 24365
Protection Type: protected-preferred
Maximum SID Depth: 10
Dynamic (valid)
Metric Type: IGP, Path Accumulated Metric: 30
16006 [Prefix-SID, 6.6.6.6]
Attributes:
Binding SID: 24365
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#
Affinity: が何故か反映されない。 include-all：BLUE ／ metric type：TE にしても同じ結果でした。 何か bug を踏んだ予感がします。
6.4 include-any：BLUE and RED ／ metric type：TE
指定した1つ以上のカラーが一致するという制約条件に変更します。
RP/0/RP0/CPU0:h_N1(config-sr-te-path-pref-const)#affinity ? exclude-any Affinity attributes to exclude - presence of at least one excludes link include-all Affinity attributes - all must be included include-any Affinity attributes - at least one must be included <cr> RP/0/RP0/CPU0:h_N1(config-sr-te-path-pref-const)#
ということで、”include-any：RED & BLUE ”に変更します。
RP/0/RP0/CPU0:h_N1(config)#seg tr po LINK_COLOR_CONSTRAINS_POLICY can pref 100$
RP/0/RP0/CPU0:h_N1(config-sr-te-path-pref-const-aff)#no include-all
RP/0/RP0/CPU0:h_N1(config-sr-te-path-pref-const-aff)#include-any
RP/0/RP0/CPU0:(config-sr-te-path-pref-const-aff-rule)#name RED
RP/0/RP0/CPU0:(config-sr-te-path-pref-const-aff-rule)#name BLUE
RP/0/RP0/CPU0:(config-sr-te-path-pref-const-aff-rule)#show
Sun Apr 2 14:29:20.521 UTC
segment-routing
traffic-eng
policy LINK_COLOR_CONSTRAINS_POLICY
candidate-paths
preference 100
constraints
affinity
include-any
name RED
name BLUE
!
!
!
!
!
!
!
!
RP/0/RP0/CPU0:(config-sr-te-path-pref-const-aff-rule)#
traceroute を確認するとぱっと見は想定通りですが、SID-listが妙です。
RP/0/RP0/CPU0:h_N1#traceroute 6.6.6.6 source 1.1.1.1 Sun Apr 2 14:30:51.761 UTC Type escape sequence to abort. Tracing the route to 6.6.6.6 1 10.1.3.3 [MPLS: Label 16006 Exp 0] 19 msec 5 msec 4 msec 2 10.3.5.5 [MPLS: Label 16006 Exp 0] 6 msec 4 msec 3 msec 3 10.5.6.6 10 msec * 5 msec RP/0/RP0/CPU0:h_N1#
許可リンク（RED & BLUE）を経由する、かつ IGP のメトリックが最小となる経路の SR-TE が動的に生成されることを想定していました。
SR-TE ポリシーを確認するとやっぱりおかしい。down しているし affinity が足りないです。
RP/0/RP0/CPU0:h_N1#show segment-routing traffic-eng policy
Sun Apr 2 14:33:39.609 UTC
SR-TE policy database
---------------------
Color: 6666, End-point: 6.6.6.6
Name: srte_c_6666_ep_6.6.6.6
Status:
★ Admin: up Operational: down for 00:05:41 (since Apr 2 14:27:57.938)
Candidate-paths:
Preference: 100 (configuration)
Name: LINK_COLOR_CONSTRAINS_POLICY
Requested BSID: 24365
Constraints:
Protection Type: protected-preferred
★ Affinity:
★ include-any:
★ RED
Maximum SID Depth: 10
Dynamic (invalid)
Last error: No path found
Metric Type: IGP, Path Accumulated Metric: 30
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#
7. 検証から分かったこと
Link Color Constraints は意図した動作をするものとしないものがある。 IOS-XR 7.7.1 に変えても、”include-any ”と ”include-all ”は意図した動作をしませんでした。
8. 参考
① Constraints
www.cisco.com
② Segment Routing Traffic Engineering – Dynamic Candidate PathのLink Color
y-network.jp
次回は、SR & L3VPN について記事を書きます。
最後までお読みいただきありがとうございました！
