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When redistributing routing information across domains, provisioning of multi-domain services (Layer 2 VPN and Layer 3 VPN) has its own complexity and scalability issues. Effective Cisco IOS XE Everest 16.6.1, On-Demand Next Hop (ODN) triggers delegation of computation of an end-to-end LSP to a PCE controller including constraints and policies without doing any redistribution. It then installs the reapplied multi-domain LSP for the duration of the service into the local forwarding information base (FIB).
 Note |
SR-TE On-Demand Next Hop is available only on the Cisco RSP2 Module. |
ODN anycast SID is not supported.
ODN for IPv6 is not supported.
SR ODN Tunnel is not supported on BGP NSR. It is only supported on BGP NSF.
On-Demand Next hop leverages upon BGP Dynamic SR-TE capabilities and adds the path computation (PCE) ability to find and download the end to end path based on the requirements. ODN triggers an SR-TE auto-tunnel based on the defined BGP policy. As shown in the following figure, an end-to-end path between ToR1 and AC1 can be established from both ends based on low latency or other criteria for VRF (L3VPN) or IPv4 services. The work-flow for ODN is summarized as follows:
PCE controller collects topology and SIDs information via BGP Link State (BGP-LS). For more information on BGP-LS, refer BGP Link-State .
If NSO controller is enabled, it configures L3VPN VRF or IPv4 prefixes and requests are sent to ToR1 and AC1.
ToR1 and AC1 checks if an LSP toward each other exists. If not, a request is sent to the PCE controller to compute that SR-TE path that matches SR-TE policy that is carried through BGP.
PCE controller computes the path and replies with a label stack (18001, 18002, 16001, example in ToR1).
ToR1 and AC1 create an SR-TE auto-tunnel and reply to the NSO controller indicating that the LSP for VRF or IPv4 is up and operational.
The fast convergence "default optimize" feature modifies the default settings of all the protocols to recommended defaults for fast convergence. To revert the defaults to pre-fast-convergence settings for both IS-IS and OSPF, routing-default-optimize command is used. This command sends signals to IS-IS and OSPF and modifies the default configuration for these protocols.
By default, the fast convergence setting is enabled which means when you upgrade the software, you can automatically see the new behavior. This makes easier integration of the devices in a multivendor deployment and reduces support cases for poor convergence.
When default optimize is disabled, existing protocol default configuration is used. When default optimize is enabled, new protocol defaults are used. The show running configurations does not display configuration lines for default settings even when default settings are being used.
A configuration of a protocol overrides the default, but a change to default optimize does not override any configuration.
The following is the sample output of spf-interval command in IS-IS:
Device(config-if)# router isis
Device(config-router)# spf-interval 10 5500 5500
If a non-default value is configured, it is displayed in show running configuration output:
Device(config-router)# spf-interval 5 50 200
Device(config-router)# do show run | inc spf-interval
spf-interval 5 50 200
You can revert to the default values by configuring the default values or by removing the non-default configuration.
The following table summarizes the configuration impacted by default optimize:
|
IS-IS command |
Parameters |
Default optimize disabled |
Default optimize enabled |
|---|---|---|---|
|
fast-flood |
|||
|
number of LSPs flooded back-to-back |
Disabled |
10 |
|
|
spf-interval |
|||
|
Initial (milliseconds) |
5500 |
50 |
|
|
Secondary (milliseconds) |
5500 |
200 |
|
|
Max (seconds) |
10 |
5 |
|
|
prc-interval |
|||
|
Initial (milliseconds) |
2000 |
50 |
|
|
Secondary (milliseconds) |
5000 |
200 |
|
|
Max (seconds) |
5 |
5 |
|
|
lsp-gen-interval |
|||
|
Initial (milliseconds) |
50 |
50 |
|
|
Secondary (milliseconds) |
5000 |
200 |
|
|
Max (seconds) |
5 |
5 |
|
|
log-adjacency-changes |
disabled |
enabled |
The following table summarizes the configuration impacted by default optimize for OSPFv2/v3:
|
OSPF command |
Parameters |
Default optimize disabled |
Default optimize enabled |
|---|---|---|---|
|
timers throttle spf |
|||
|
Initial (milliseconds) |
5500 |
50 |
|
|
Secondary (milliseconds) |
10000 |
200 |
|
|
Max (seconds) |
10 |
5 |
|
|
timers throttle lsa all |
|||
|
Initial (milliseconds) |
0 |
50 |
|
|
Secondary (milliseconds) |
5000 |
200 |
|
|
Max (seconds) |
5 |
5 |
|
|
timers lsa arrival |
|||
|
milliseconds |
1000 |
100 |
The following is the sample output of show ip ospf command for OSPFv2 with the default-optimize values.
Device# show ip ospf
Routing Process "ospf 10" with ID 1.1.1.1
Start time: 00:00:01.471, Time elapsed: 03:00:34.706
Supports only single TOS(TOS0) routes
Supports opaque LSA
Supports Link-local Signaling (LLS)
Supports area transit capability
Supports NSSA (compatible with RFC 3101)
Supports Database Exchange Summary List Optimization (RFC 5243)
Event-log enabled, Maximum number of events: 1000, Mode: cyclic
Router is not originating router-LSAs with maximum metric
Initial SPF schedule delay 50 msecs
Minimum hold time between two consecutive SPFs 200 msecs
Maximum wait time between two consecutive SPFs 5000 msecs
Incremental-SPF disabled
Initial LSA throttle delay 50 msecs
Minimum hold time for LSA throttle 200 msecs
Maximum wait time for LSA throttle 5000 msecs
Minimum LSA arrival 100 msecs
LSA group pacing timer 240 secs
Interface flood pacing timer 33 msecs
Retransmission pacing timer 66 msecs
EXCHANGE/LOADING adjacency limit: initial 300, process maximum 300
Number of external LSA 18. Checksum Sum 0x075EB2
Number of opaque AS LSA 0. Checksum Sum 0x000000
Number of DCbitless external and opaque AS LSA 0
Number of DoNotAge external and opaque AS LSA 0
Number of areas in this router is 1. 1 normal 0 stub 0 nssa
Number of areas transit capable is 0
External flood list length 0
IETF NSF helper support enabled
Cisco NSF helper support enabled
Reference bandwidth unit is 100 mbps
Area BACKBONE(0)
Number of interfaces in this area is 4 (2 loopback)
Area has RRR enabled
Area has no authentication
SPF algorithm last executed 02:27:23.736 ago
SPF algorithm executed 20 times
Area ranges are
Number of LSA 94. Checksum Sum 0x321DCF
Number of opaque link LSA 0. Checksum Sum 0x000000
Number of DCbitless LSA 0
Number of indication LSA 0
Number of DoNotAge LSA 0
Flood list length 0
The following is the sample output of show ospf command for OSPFv3 with the default-optimize values.
Device# show ospfv3
OSPFv3 10 address-family ipv6
Router ID 11.11.11.11
Supports NSSA (compatible with RFC 3101)
Supports Database Exchange Summary List Optimization (RFC 5243)
Event-log enabled, Maximum number of events: 1000, Mode: cyclic
Router is not originating router-LSAs with maximum metric
Initial SPF schedule delay 50 msecs
Minimum hold time between two consecutive SPFs 200 msecs
Maximum wait time between two consecutive SPFs 5000 msecs
Initial LSA throttle delay 50 msecs
Minimum hold time for LSA throttle 200 msecs
Maximum wait time for LSA throttle 5000 msecs
Minimum LSA arrival 100 msecs
LSA group pacing timer 240 secs
Interface flood pacing timer 33 msecs
Retransmission pacing timer 66 msecs
Retransmission limit dc 24 non-dc 24
EXCHANGE/LOADING adjacency limit: initial 300, process maximum 300
Number of external LSA 0. Checksum Sum 0x000000
Number of areas in this router is 1. 1 normal 0 stub 0 nssa
Graceful restart helper support enabled
Reference bandwidth unit is 100 mbps
RFC1583 compatibility enabled
Area BACKBONE(0)
Number of interfaces in this area is 2
SPF algorithm executed 7 times
Number of LSA 3. Checksum Sum 0x012426
Number of DCbitless LSA 0
Number of indication LSA 0
Number of DoNotAge LSA 0
Flood list length 0Effective Cisco IOS XE Gibraltar 16.11.1, the router supports:
MPLS TE new SR-TE policy command—segment-routing traffic-eng
Color-extended community
Affinity constraints
Disjointness constraints
Effective Cisco IOS XE Gibraltar 16.11.1, a new command (segment-routing traffic-eng ) is added to configure the SR policy under segment routing. For information on using this command, see the “Configuring Color-Extended Community section.
In earlier releases, the router created segment routed Traffic Engineering (SR-TE) tunnels based on a tunnel-profile or attribute set. As part of this functionality, an inbound route-map with a “match community” and “set attribute-set” was added on the ingress node and the route-map matched against communities received in the BGP updates. A BGP update with a matching community would initiate an SR-TE tunnel for the nexthop TE-profile.
However, effective Cisco IOS XE Gibraltar 16.11.1, ‘color extended’ community is now added as follows:
An SR-TE policy is created on the ingress router for the Color-Endpoint pair.
The egress router adds the ‘color extended’ community to the BGP updates that require a Traffic-Engineered path.
Affinity is a 32-bit constraint used by the PCE and PCALC for calculating paths that take the "affinity constraint" into account.
Affinity constraints let you assign, or map, color names for path affinities. After mappings are defined, the attributes can be referred to by the corresponding color name in the command.
Affinity maps are used to map operator-defined color names to a bit position in the affinity bitmap
Supported Affinity constraints are:
include-all—indicates that constrained shortest path first (CSPF) includes a link when calculating a path, only if each link administrative group bit has the same name as each affinity bit.
include-any—indicates that CSPF includes a link when calculating a path, if at least one link administrative group bit has the same name as an affinity bit.
exclude-any—indicates that CSPF excludes a link when calculating a path, if any link administrative group bit has the same name as an affinity bit.
Disjointness is used to describe two or more services that must be completely disjoint of each other. Disjointness is useful for providing traffic flow redundancy in the network.
Disjointness is controlled by the PCE. The PCE learns of the network topology through an IGP (OSPF or IS-IS) through the BGP-LS protocol and is capable of computing paths based on the IGP or TE metric.
The PCE uses the disjoint policy to compute two lists of segments that steer traffic from the source node to thewards destination node along disjoint paths. Disjoint paths can originate from either the same or different head-ends.
A "disjoint level" refers to the type of resources that should not be shared by the two computed paths. The PCE supports the following disjoint path computations:
Link
Node
Shared risk link group (SRLG)
When the first request is received from Path Computation client (PCC) or an ingress node, with a given disjoint-group ID, a list of segments is computed based on the metric requested, encoding the shortest path from source to destination.
When the second request is received with the same disjoint-group ID, based on the information received in both requests, the PCE computes two disjoint paths from the source to the destination.
Both paths are computed at the same time. The shortest list of segments is calculated to steer traffic on the computed paths.
On the Cisco ASR 920 routers, the total stack limit is five labels.
Router# show mpls outlabel-stack reservation
Application Outlabels Status
Reserved
bgp 0 COMPLETE
transport 0 COMPLETE
vpn 1 COMPLETE ------ 1 Label is used for VPN service
Platform Max OutLabels:5
Total Available OutLabels:4
Reg apps: MPLS-TE(4) OSPF-1(4)
Router#
The maximum number of SR-TE ODN policies supported is 500.
Static SR-TE policy is not supported.
SR-TE policy counters are not supported on the Cisco ASR 920 routers.
SR-TE policy goes down only after 60 seconds when the connection to PCEP is disconnected due to any reason.
6PE and 6VPE services are supported only if the number of transport labels used for SR-TE policy does not exceed two labels.
Perform the following steps to configure on-demand next hop for SR-TE. The following figure is used as a reference to explain the configuration steps.
vrf definition sr
rd 100:100
route-target export 100:100
route-target import 100:100
!
address-family ipv4
exit-address-family
!
address-family ipv6
exit-address-family
!
interface gigabitEthernet0/0/11
vrf forwarding sr
ip address 30.30.30.1 255.255.255.0
route-map BGP_TE_MAP permit 9
match ip address L3VPN_ODN_ROUTES
set community 3276850
ip access-list extended L3VPN_ODN_ROUTES
permit ip 30.30.30.1 255.255.0.0 any
router bgp 100 <-- This BGP configuration applies to the tailend
bgp router-id 172.16.0.1
bgp log-neighbor-changes
bgp graceful-restart
no bgp default ipv4-unicast
neighbor 10.0.0.2 remote-as 100
neighbor 10.0.0.2 update-source Loopback0
address-family ipv4
neighbor 10.0.0.2 activate
neighbor 10.0.0.2 send-community both
neighbor 10.0.0.2 next-hop-self
exit-address-family
address-family vpnv4
neighbor 10.0.0.2 activate
neighbor 10.0.0.2 send-community both
neighbor 10.0.0.2 route-map BGP_TE_MAP out
exit-address-family
address-family link-state link-state
neighbor 10.0.0.2 activate
exit-address-family
address-family ipv4 vrf sr
redistribute connected
exit-address-family
route-map BGP_TE_MAP permit 9
match ip address traffic
set community 3276850
ip access-list extended traffic
permit ip 10.0.0.1 255.255.0.0 any
router bgp 100 <-- This BGP configuration applies to the headend
bgp router-id 192.168.0.2
bgp log-neighbor-changes
bgp graceful-restart
no bgp default ipv4-unicast
neighbor 10.0.0.2 remote-as 100
neighbor 10.0.0.2 update-source Loopback0
address-family ipv4
neighbor 10.0.0.2 activate
neighbor 10.0.0.2 send-community both
neighbor 10.0.0.2 next-hop-self
exit-address-family
address-family vpnv4
neighbor 10.0.0.2 activate
neighbor 10.0.0.2 send-community both
neighbor 10.0.0.2 route-map BGP_TE_MAP in
exit-address-family
address-family link-state link-state
neighbor 10.0.0.2 activate
exit-address-family
address-family ipv4 vrf sr
redistribute connected
exit-address-family
route-map BGP_TE_MAP permit 9
match community 1
set attribute-set BGP_TE5555
ip community-list 1 permit 3276850
mpls traffic-eng lsp attributes BGP_TE5555
path-selection metric igp
pce
route-map BGP_TE_MAP permit 9
match community 1
set attribute-set BGP_TE5555
ip community-list 1 permit 3276850
mpls traffic-eng lsp attributes BGP_TE5555
path-selection metric igp
pce
end
mpls traffic-eng tunnels
mpls traffic-eng pcc peer 10.0.0.3 source 10.0.0.4 precedence 255
mpls traffic-eng auto-tunnel p2p tunnel-num min 2000 max 5000
mpls traffic-eng tunnels
interface GigabitEthernet0/2/0
ip address 101.102.6.1 255.255.255.0
ip router isis 1
mpls traffic-eng tunnels
isis network point-to-point
interface GigabitEthernet0/3/1
vrf forwarding sr
ip address 101.107.3.1 255.255.255.0
negotiation auto
end
router isis 1
net 49.0002.0000.0000.0003.00
ispf level-1-2
metric-style wide
nsf cisco
nsf interval 0
distribute link-state
segment-routing mpls
segment-routing prefix-sid-map advertise-local
redistribute static ip level-1-2
mpls traffic-eng router-id Loopback0
mpls traffic-eng level-1
mpls traffic-eng level-2
router bgp 100
bgp router-id 10.0.0.2
bgp log-neighbor-changes
bgp graceful-restart
no bgp default ipv4-unicast
neighbor 10.0.0.3 remote-as 100
neighbor 10.0.0.3 update-source Loopback0
address-family ipv4
neighbor 10.0.0.3 activate
exit-address-family
Device# show bgp li li summary
BGP router identifier 10.0.0.3, local AS number 100
BGP generic scan interval 60 secs
Non-stop routing is enabled
BGP table state: Active
Table ID: 0x0 RD version: 1436
BGP main routing table version 1436
BGP NSR Initial initsync version 1 (Reached)
BGP NSR/ISSU Sync-Group versions 0/0
BGP scan interval 60 secs
BGP is operating in STANDALONE mode.
Process RcvTblVer bRIB/RIB LabelVer ImportVer SendTblVer StandbyVer
Speaker 1436 1436 1436 1436 1436
0
Neighbor Spk AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down St/PfxRcd
10.0.0.2 0 100 19923 17437 1436 0 0 1w2d 103
Device# show pce ipv4 topo | b Node 3
Node 3
TE router ID: 10.0.0.2
Host name: R3
ISIS system ID: 0000.0000.0003 level-1
ISIS system ID: 0000.0000.0003 level-2
Prefix SID:
Prefix 10.0.0.2, label 20011 (regular)
Note |
The above show command is run only on the PCE server, for example the Cisco ASR 9000 Series Aggregation Services Routers. |
The ODN verifications are based on L3VPN VRF prefixes.
Device# show pce client peer
PCC's peer database:
--------------------
Peer address: 10.0.0.3 (best PCE)
State up
Capabilities: Stateful, Update, Segment-Routing
Device# show pce ipv4 peer
PCE's peer database:
--------------------
Peer address: 10.0.0.4
State: Up
Capabilities: Stateful, Segment-Routing, Update
Peer address: 172.16.0.5
State: Up
Capabilities: Stateful, Segment-Routing, Update
Note |
The above show command is run only on the PCE server, for example the Cisco ASR 9000 Series Aggregation Services Routers. |
Device# show ip route 192.168.0.1
% Network not in table
Device# show ip route vrf sr
Routing Table: sr
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
a - application route
+ - replicated route, % - next hop override, p - overrides from PfR
Gateway of last resort is not set
C L
B
10.0.0.6/8 is variably subnetted, 2 subnets, 2 masks
10.0.0.7/24 is directly connected, GigabitEthernet0/3/1
10.0.0.7/32 is directly connected, GigabitEthernet0/3/1
10.0.0.8/24 is subnetted, 1 subnets
10.0.0.9 [200/0] via binding label: 865, 4d21h
Device# show ip bgp vpnv4 vrf sr 106.107.4.0
BGP routing table entry for 100:100:106.107.4.0/24, version 3011
Paths: (1 available, best #1, table sr)
Not advertised to any peer
Refresh Epoch 4
Local
192.168.0.1 (metric 10) (via default) from 10.0.0.2 (10.0.0.2)
Origin incomplete, metric 0, localpref 100, valid, internal, best
Community: 3276850
Extended Community: RT:100:100
Originator: 192.168.0.1, Cluster list: 10.0.0.2
mpls labels in/out nolabel/1085
binding SID: 865 (BGP_TE5555)
rx pathid: 0, tx pathid: 0x0
Device# show ip route vrf sr 106.107.4.0
Routing Table: sr
Routing entry for 106.107.4.0/24
Known via "bgp 100", distance 200, metric 0, type internal
Routing Descriptor Blocks:
* Binding Label: 865, from 10.0.0.2, 4d22h ago
Route metric is 0, traffic share count is 1
AS Hops 0
MPLS label: 1085
MPLS Flags: NSF
Device# show ip cef label-table
Label Next Hop Interface
0 no route
865 attached Tunnel2000
Device# show ip cef vrf sr 106.107.4.0 detail
10.0.0.8/24, epoch 15, flags [rib defined all labels]
recursive via 865 label 1085
attached to Tunnel2000
Device# show mpls traffic-eng tunnels
P2P TUNNELS/LSPs:
Name: R1_t2000 (Tunnel2000) Destination: 192.168.0.1 Ifhandle: 0x6F5
(auto-tunnel for BGP TE)
Status:
Admin: up Oper: up Path: valid Signalling: connected---.. auto-tunnel
2000
path option 1, (SEGMENT-ROUTING) (PCE) type dynamic (Basis for Setup, path weight
10)
Config Parameters:
Bandwidth: 0 kbps (Global) Priority: 7 7 Affinity: 0x0/0xFFFF
Metric Type: IGP (interface)
Path Selection:
Protection: any (default)
Path-selection Tiebreaker:
Global: not set Tunnel Specific: not set Effective: min-fill (default)
Hop Limit: disabled
Cost Limit: disabled
Path-invalidation timeout: 10000 msec (default), Action: Tear
AutoRoute: disabled LockDown: disabled Loadshare: 0 [0] bw-based auto-bw: disabled
Attribute-set: BGP_TE5555--- attribute-set
Fault-OAM: disabled, Wrap-Protection: disabled, Wrap-Capable: No
Active Path Option Parameters:
State: dynamic path option 1 is active
BandwidthOverride: disabled LockDown: disabled Verbatim: disabled
PCEP Info:
Delegation state: Working: yes Protect: no
Working Path Info:
Request status: processed
Created via PCRep message
PCE metric: 30, type: IGP
Reported paths:
Tunnel Name: Tunnel2000_w
LSPs:
LSP[0]:
from PCE server: 10.0.0.3-- via PCE server
source 10.0.0.4, destination 192.168.0.1, tunnel ID 2000, LSP ID 1
State: Admin up, Operation active
Binding SID: 865
Setup type: SR
Bandwidth: requested 0, used 0
LSP object:
PLSP-ID 0x807D0, flags: D:0 S:0 R:0 A:1 O:2
Metric type: IGP, Accumulated Metric 0
ERO:
SID[0]: Adj, Label 2377, NAI: local 101.102.6.1 remote 10.0.0.10
SID[1]: Unspecified, Label 17, NAI: n/a
SID[2]: Unspecified, Label 20, NAI: n/a
History:
Tunnel:
Time since created: 4 days, 22 hours, 21 minutes
Time since path change: 4 days, 22 hours, 21 minutes
Number of LSP IDs (Tun_Instances) used: 1
Current LSP: [ID: 1]
Uptime: 4 days, 22 hours, 21 minutes
Tun_Instance: 1
Segment-Routing Path Info (isis level-1)
Segment0[Link]: 101.102.6.1 - 10.0.0.10, Label: 2377
Segment1[ - ]: Label: 17
Segment2[ - ]: Label: 20
Device# show pce client lsp brief
PCC's tunnel database:
----------------------
Tunnel Name: Tunnel2000_w
LSP ID 1
Tunnel Name: Tunnel2000_p
R1# sh pce client lsp detail
PCC's tunnel database:
----------------------
Tunnel Name: Tunnel2000_w
LSPs:
LSP[0]:
source 10.0.0.4, destination 192.168.0.1, tunnel ID 2000, LSP ID 1
State: Admin up, Operation active
Binding SID: 865
Setup type: SR
Bandwidth: requested 0, used 0
LSP object:
PLSP-ID 0x807D0, flags: D:0 S:0 R:0 A:1 O:2
Metric type: IGP, Accumulated Metric 0
ERO:
SID[0]: Adj, Label 2377, NAI: local 101.102.6.1 remote 10.0.0.10
SID[1]: Unspecified, Label 17, NAI: n/a
SID[2]: Unspecified, Label 20, NAI: n/a
Device# show pce lsp summary
PCE's LSP database summary:
--------------------------------
All peers:
Number of LSPs: 1
Operational: Up: 1 Down: 0
Admin state: Up: 1 Down: 0
Setup type: RSVP: 0 Segment routing: 1
Peer 10.0.0.4:
Number of LSPs: 1
Operational: Up: 1 Down: 0
Admin state: Up: 1 Down: 0
Setup type: RSVP: 0 Segment routing: 1
Device# show pce lsp detail
PCE's tunnel database:
----------------------
PCC 10.0.0.4:
Tunnel Name: Tunnel2000_w
LSPs:
LSP[0]:
source 10.0.0.4, destination 192.168.0.1, tunnel ID 2000, LSP ID 48
State: Admin up, Operation active
Binding SID: 872
PCEP information:
plsp-id 526288, flags: D:1 S:0 R:0 A:1 O:2
Reported path:
Metric type: IGP, Accumulated Metric 0
SID[0]: Adj, Label 885, Address: local 10.0.0.9 remote 10.0.0.10
SID[1]: Unknown, Label 17,
SID[2]: Unknown, Label 20,
Computed path:
Computed Time: Tue Dec 20 13:12:57 2016 (00:11:53 ago)
Metric type: IGP, Accumulated Metric 30
SID[0]: Adj, Label 885, Address: local 10.0.0.9 remote 10.0.0.10
SID[1]: Adj, Label 17, Address: local 10.0.0.12 remote 10.0.0.13
SID[2]: Adj, Label 20, Address: local 10.0.0.14 remote 10.0.0.14
Recorded path:
None
Device# interface GigabitEthernet0/2
Device(config-if)# shut
Device# show ip route vrf sr
Routing Table: sr
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
a - application route
+ - replicated route, % - next hop override, p - overrides from PfR
Gateway of last resort is not set
10.0.0.6/8 is variably subnetted, 2 subnets, 2 masks
C 10.0.0.7/24 is directly connected, GigabitEthernet0/3/1
L 10.0.0.8/32 is directly connected, GigabitEthernet0/3/1
Device# show mpls traffic-eng tunnels
P2P TUNNELS/LSPs:
P2MP TUNNELS:
P2MP SUB-LSPS:
Consider the following topology:
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SR-TE Policy Headend Configuration on Node R3
segment-routing traffic-eng
on-demand color 100
authorize restrict
ipv4 prefix-list R9350_BGP_INTER_DOMAIN
candidate-paths
preference 1
constraints
segments
dataplane mpls
!
!
dynamic
pcep
!
!
!
!
pcc
pce address <pce loopback ip>source-address <pcc loopback ip>
!
SR-TE Policy Taileend Configuration on Node R9
route-map R9_R3_R5_R2_BGP_INTER_DOMAIN permit 10
match ip address prefix-list R9350_BGP_INTER_DOMAIN
set extcommunity color 100 --------------- Extended Color community configuration
route-map R9_R3_R5_R2_BGP_INTER_DOMAIN permit 20
ip prefix-list R9350_BGP_INTER_DOMAIN seq 35 permit 50.0.0.0/11 le 32
router bgp 1
address-family vpnv4
neighbor 201.201.201.201 activate
neighbor 201.201.201.201 send-community both
neighbor 201.201.201.201 route-map R9_R3_R5_R2_BGP_INTER_DOMAIN out
neighbor 206.206.206.206 activate
neighbor 206.206.206.206 send-community both
neighbor 206.206.206.206 route-map R9_R3_R5_R2_BGP_INTER_DOMAIN out
exit-address-family
!
In the SR-TE ODN color template, to select the metric type, choose either igp or te :
Router(config-srte-odn-path-pref-dyn-metric)# type ?
igp Specify IGP metric
te Specify TE metric
segment-routing traffic-eng
interface GigabitEthernet0/2/3
affinity
name 1
on-demand color 100
authorize restrict
ipv4 prefix-list R9350_BGP_INTER_DOMAIN
candidate-paths
preference 1
constraints
segments
dataplane mpls
!
affinity -------------------- Affinity configuration
include-any ------------ Affinity Type configuration
name 1 ---------------- Affinity Name configuration
!
!
dynamic
pcep
!
!
!
!
pcc
pce address <pce loopback ip> source-address <pcc loopback ip>
!
affinity-map ----------------------- Affinity Map configuration
name 1 bit-position 1
segment-routing traffic-eng
on-demand color 100
authorize restrict
ipv4 prefix-list R9350_BGP_INTER_DOMAIN
candidate-paths
preference 1
constraints
segments
dataplane mpls
!
affinity
include-any
name 1
!
!
association-group -------------------- Disjointness configuration
identifier 1
disjointness type node -------------------- Disjointness Type configuration
source 1.0.0.0
!
!
dynamic
pcep
!
!
!
!
pcc
pce address <pce loopback ip> source-address <pcc loopback ip>
!
affinity-map
name 1 bit-position 1
SR-TE Policy Name: 209.209.209.209|100
Router# show segment-routing traffic-eng policy name 209.209.209.209|100
Name: 209.209.209.209|100 (Color: 100 End-point: 209.209.209.209)
Status:
Admin: up, Operational: up for 51:34:38 (since 01-07 06:19:08.040)- Policy state is UP
Candidate-paths:
Preference 1:
Constraints:
Affinity:
include-any: ------------- Affinity Type
1 ------------- Affinity Name
Disjointness information:
Group ID: 1, Source: 1.0.0.0
Type: Node Disjointness ------ Disjointness Type
Dynamic (pce 12.12.12.12) (active) --------- PCE Computed Candidate-path
Weight: 0, Metric Type: TE ----------------- Metric Type
Metric Type: TE, Path Accumulated Metric: 53 - Total IGP Metric from Source to Destination
18010 [Prefix-SID, 202.202.202.202] ------------------|
18007 [Prefix-SID, 211.211.211.211] ------------------| |
18002 [Prefix-SID, 207.207.207.207] ----------------- This Segment List should follow Affinity path
21 [Adjacency-SID, 10.10.20.2 - 10.10.20.1] ----------------|
Attributes:
Binding SID: 87 ---------------- Binding SID Allocated
Allocation mode: dynamic
State: Programmed
Auto-policy info:
Creator: BGP SR Policy Client
IPv6 caps enable: yes
To view detailed information about SR-TE Policy 209.209.209.209|100
Router# show segment-routing traffic-eng policy name 209.209.209.209|100 detail
Name: 209.209.209.209|100 (Color: 100 End-point: 209.209.209.209)
Status:
Admin: up, Operational: up for 00:04:19 (since 01-10 06:20:57.810)
Candidate-paths:
Preference 1:
Constraints:
Affinity:
include-any:
1
Disjointness information:
Group ID: 1, Source: 1.0.0.0
Type: Node Disjointness
Dynamic (pce 12.12.12.12) (active)
Weight: 0, Metric Type: TE
Metric Type: TE, Path Accumulated Metric: 53
18010 [Prefix-SID, 202.202.202.202]
18007 [Prefix-SID, 211.211.211.211]
18002 [Prefix-SID, 207.207.207.207]
21 [Adjacency-SID, 10.10.20.2 - 10.10.20.1]
Attributes:
Binding SID: 87
Allocation mode: dynamic
State: Programmed
Auto-policy info:
Creator: BGP SR Policy Client
IPv6 caps enable: yes
Forwarding-ID: 65711 (0x44) ------- This FWD-ID is used for forwarding traffic
Stats:
Packets: 8893 Bytes: 852848 ------- This counter indicates traffic flowing through this SRTE policy
Event history: --- This indicates event happened with this SRTE Policy
Timestamp Client Event type Context: Value
--------- ------ ---------- -------: -----
01-06 05:59:26.096 BGP SR Policy Cl Policy created Name: 209.209.209.209|100
01-06 05:59:26.096 BGP SR Policy Cl Set colour Colour: 100
01-06 05:59:26.096 BGP SR Policy Cl Set end point End-point: 209.209.209.209
01-06 05:59:26.096 BGP SR Policy Cl Set dynamic pce Path option: dynamic pce
01-06 05:59:26.480 FH Resolution Policy state UP Status: PATH RESOLVED
01-06 05:59:40.424 FH Resolution REOPT triggered Status: REOPTIMIZED
01-06 05:59:49.249 FH Resolution REOPT triggered Status: REOPTIMIZED
01-06 05:59:56.469 FH Resolution REOPT triggered Status: REOPTIMIZED
01-07 05:15:19.918 FH Resolution Policy state DOWN Status: PATH NOT RESOLVED
01-07 06:15:55.739 FH Resolution Policy state UP Status: PATH RESOLVED
01-07 06:16:08.552 FH Resolution REOPT triggered Status: REOPTIMIZED
01-07 06:19:08.040 FH Resolution Policy state DOWN Status: PATH NOT RESOLVED
01-10 06:20:57.810 FH Resolution Policy state UP Status: PATH RESOLVED
01-10 06:21:05.211 FH Resolution REOPT triggered Status: REOPTIMIZED
01-10 06:21:08.036 FH Resolution REOPT triggered Status: REOPTIMIZED
01-10 06:21:10.073 FH Resolution REOPT triggered Status: REOPTIMIZED
To check if the Affinity constraint is working, shut down any of the interfaces falling under the Affinity-defined path. If the constraint works, the SR-TE policy goes down instead of taking the another path (if available) to reach to the destination.
To check if the disjointness constraint is working, check the SR-TE policy information given by the PCE, which consists of Segment IDs used for the computed path from source to destination.
Disjointness constraint works, if the Segment IDs of both the SR-TE policies are different. For example:
SRTE Policy 1: SRTE Policy 2:
SID[0]: Node, Label 16002, NAI: 207.207.207.207 SID[0]: Node, Label 16003, NAI: 208.208.208.208
SID[1]: Node, Label 16004, NAI: 201.201.201.201 SID[1]: Node, Label 16006, NAI: 206.206.206.206
SID[2]: Node, Label 16011, NAI: 205.205.205.205 SID[2]: Node, Label 16011, NAI: 205.205.205.205
Note |
SID[2] of policies 1 and 2 is the same since destination of both the SR-TE policies is the same. |
To view the SR-TE policy and Affinity constraint in the PCE:
RP/0/RSP0/CPU0:ASR9K# show pce lsp pcc ipv4 213.213.213.213 private
Thu Jan 10 00:11:52.983 UTC
PCE's tunnel database:
----------------------
PCC 213.213.213.213:
Tunnel Name: 209.209.209.209|100
LSPs:
LSP[0]:
source 203.203.203.203, destination 209.209.209.209, tunnel ID 177, LSP ID 0
State: Admin up, Operation ---- SRTE Policy is up
Setup type: Segment Routing
Binding SID: 87
Maximum SID Depth: 4
Absolute Metric Margin: 0
Relative Metric Margin: 0%
Affinity: exclude-any 0x0 include-any 0x2 include-all 0x0 ---- This indicates Affinity taken into account by PCE
PCEP information:
PLSP-ID 0x800b1, flags: D:1 S:0 R:0 A:1 O:2 C:0
LSP Role: Disjoint LSP
State-sync PCE: None
PCC: 213.213.213.213
LSP is subdelegated to: None
Reported path:
Metric type: TE, Accumulated Metric 53
SID[0]: Node, Label 18010, Address 202.202.202.202
SID[1]: Node, Label 18007, Address 211.211.211.211
SID[2]: Node, Label 18002, Address 207.207.207.207
SID[3]: Adj, Label 21, Address: local 10.10.20.2 remote 10.10.20.1
Computed path: (Local PCE)
Computed Time: Thu Jan 10 00:09:36 UTC 2019 (00:02:17 ago)
Metric type: TE, Accumulated Metric 53
SID[0]: Node, Label 18010, Address 202.202.202.202
SID[1]: Node, Label 18007, Address 211.211.211.211
SID[2]: Node, Label 18002, Address 207.207.207.207
SID[3]: Adj, Label 21, Address: local 10.10.20.2 remote 10.10.20.1
Recorded path:
None
Disjoint Group Information:
Type Node-Disjoint, Group 1, Sub-Group 1.0.0.0
Event history (latest first):
Time Event
Thu Jan 10 00:09:37 UTC 2019 Report from 213.213.213.213 (LSP owner)
Symbolic-name: 209.209.209.209|100, LSP-ID: 0,
Source: 203.203.203.203 Destination: 209.209.209.209,
D:1, R:0, A:1 O:2, Sig.BW: 0, Act.BW: 0
Reported Path: (Metric 53)
Label 18010, Address 202.202.202.202
Label 18007, Address 211.211.211.211
Label 18002, Address 207.207.207.207
Label 21, Address: local 10.10.20.2 remote 10.10.20.1
Chng:0, AssoChng:0
Thu Jan 10 00:09:36 UTC 2019 Update to 213.213.213.213 (PCC)
Symbolic-name: 209.209.209.209|100, LSP-ID: 0, D:1
Path: (Metric 53)
Label 18010, Address 202.202.202.202
Label 18007, Address 211.211.211.211
Label 18002, Address 207.207.207.207
Label 21, Address: local 10.10.20.2 remote 10.10.20.1
Thu Jan 10 00:09:36 UTC 2019 Path Computation (Disjoint LSP)
Symbolic-name: 209.209.209.209|100, LSP-ID: 0, D:1
Source: 203.203.203.203 Destination: 209.209.209.209
Status: Disjoint Path Success
Wed Jan 09 23:54:42 UTC 2019 Update to 213.213.213.213 (PCC)
Symbolic-name: 209.209.209.209|100, LSP-ID: 0, D:1
Path: (Metric 53)
Label 18007, Address 211.211.211.211
Label 18002, Address 207.207.207.207
Label 21, Address: local 10.10.20.2 remote 10.10.20.1
Wed Jan 09 23:54:42 UTC 2019 Path Computation (Disjoint LSP)
Symbolic-name: 209.209.209.209|100, LSP-ID: 0, D:1
Source: 203.203.203.203 Destination: 209.209.209.209
Status: Fallback Node to Shortest Path
Computed Path: (Metric 53)
Label 18007, Address 211.211.211.211
Label 18002, Address 207.207.207.207
Label 21, Address: local 10.10.20.2 remote 10.10.20.1
Wed Jan 09 23:54:21 UTC 2019 Path Computation (Disjoint LSP)
Symbolic-name: 209.209.209.209|100, LSP-ID: 0, D:1
Source: 203.203.203.203 Destination: 209.209.209.209
Status: Disjoint Path Success
Computed Path: (Metric 53)
Label 18010, Address 202.202.202.202
Label 18007, Address 211.211.211.211
Label 18002, Address 207.207.207.207
Label 21, Address: local 10.10.20.2 remote 10.10.20.1
Computed Path: (Metric 53)
Label 18010, Address 202.202.202.202
Label 18007, Address 211.211.211.211
Label 18002, Address 207.207.207.207
Label 21, Address: local 10.10.20.2 remote 10.10.20.1
Thu Jan 10 00:09:05 UTC 2019 Path Computation (Disjoint LSP)
Symbolic-name: 209.209.209.209|100, LSP-ID: 0, D:1
Source: 203.203.203.203 Destination: 209.209.209.209
Status: Fallback Node to Shortest Path
Computed Path: (Metric 53)
Label 18007, Address 211.211.211.211
Label 18002, Address 207.207.207.207
Label 21, Address: local 10.10.20.2 remote 10.10.20.1
Wed Jan 09 23:54:42 UTC 2019 Report from 213.213.213.213 (LSP owner)
Symbolic-name: 209.209.209.209|100, LSP-ID: 0,
Source: 203.203.203.203 Destination: 209.209.209.209,
D:1, R:0, A:1 O:2, Sig.BW: 0, Act.BW: 0
Reported Path: (Metric 53)
Label 18007, Address 211.211.211.211
Label 18002, Address 207.207.207.207
Label 21, Address: local 10.10.20.2 remote 10.10.20.1
Chng:0, AssoChng:0
RP/0/RSP0/CPU0:ASR9K#
To view dispointness between policies 1 and 2:
RP/0/RSP0/CPU0:ASR9K# show pce association type link group-id 3
Wed Aug 29 05:56:52.228 UTC
PCE's association database:
----------------------
Association: Type Link-Disjoint, Group 3, Sub-Group 1.0.0.0, Not Strict
Associated LSPs:
LSP[0]:
PCC 213.213.213.213, tunnel name 209.209.209.209|104, PLSP ID 524460, tunnel ID 172, LSP ID 0, Configured on PCC
LSP[1]:
PCC 213.213.213.213, tunnel name 209.209.209.209|105, PLSP ID 524461, tunnel ID 173, LSP ID 0, Configured on PCC
Status: Satisfied --------------- This indicates that Disjointness between SRTE Policies is working
RP/0/RSP0/CPU0:ASR9K#
If SR-TE policy is down, check the status of the SR-TE Policy under the SR-TE policy information
Router# show segment-routing traffic-eng policy name 209.209.209.209|100
Name: 209.209.209.209|106 (Color: 106 End-point: 209.209.209.209)
Status:
Admin: up, Operational: down for 00:00:18 (since 01-10 13:06:42.142)
Candidate-paths:
Preference 1:
Constraints:
Affinity:
include-any:
1
Dynamic (pce) (inactive)
Weight: 0, Metric Type: IGP
Attributes:
Binding SID: 269
Allocation mode: dynamic
State: Programmed
Auto-policy info:
Creator: BGP SR Policy Client
IPv6 caps enable: yes
Router#
Note |
The possible reasons for the policy being down are:
|
To check the SR-TE policy status on the PCE:
RP/0/RSP0/CPU0:ASR9K#show pce lsp pcc ipv4 213.213.213.213 private
Thu Jan 10 00:11:52.983 UTC
PCE's tunnel database:
----------------------
PCC 213.213.213.213:
Tunnel Name: 209.209.209.209|100
LSPs:
LSP[0]:
source 203.203.203.203, destination 209.209.209.209, tunnel ID 177, LSP ID 0
State: Admin up, Operation active ----- SRTE Policy is up
Setup type: Segment Routing
Binding SID: 87
Maximum SID Depth: 4
Absolute Metric Margin: 0
Relative Metric Margin: 0%
Affinity: exclude-any 0x0 include-any 0x2 include-all 0x0 --- This indicates Affinity is taken into account by the PCE
PCE is aware of the network topology. This information is used for path computation using the following command. This information is also used to determine if nodes and links are present and have the expected attributes (IGP/TE admin weights, SIDs and so on).
RP/0/RSP0/CPU0:ASR9K# show pce ipv4 topology
Tue Jan 15 01:36:20.298 UTC
PCE's topology database - detail:
---------------------------------
Node 1
TE router ID: 207.207.207.207
Host name: 920-R7
ISIS system ID: 0000.0000.0207 level-1 ASN: 1
ISIS system ID: 0000.0000.0207 level-2 ASN: 1
Prefix SID:
ISIS system ID: 0000.0000.0207 level-1 ASN: 1 domain ID: 0
Prefix 207.207.207.207, label 16002 (regular), flags: N
ISIS system ID: 0000.0000.0207 level-1 ASN: 1 domain ID: 0
Prefix 207.207.207.207, label 18002 (strict), flags: N
ISIS system ID: 0000.0000.0207 level-2 ASN: 1 domain ID: 0
Prefix 207.207.207.207, label 16002 (regular), flags: N
ISIS system ID: 0000.0000.0207 level-2 ASN: 1 domain ID: 0
Prefix 207.207.207.207, label 18002 (strict), flags: N
SRGB INFO:
ISIS system ID: 0000.0000.0207 level-1 ASN: 1
SRGB Start: 16000 Size: 8000
ISIS system ID: 0000.0000.0207 level-2 ASN: 1
SRGB Start: 16000 Size: 8000
Link[0]: local address 10.10.21.1, remote address 10.10.21.2
Local node:
ISIS system ID: 0000.0000.0207 level-1 ASN: 1
Remote node:
TE router ID: 208.208.208.208
Host name: 920-R8
ISIS system ID: 0000.0000.0208 level-1 ASN: 1
Metric: IGP 10, TE 10, Latency 10
Bandwidth: Total 1250000000 Bps, Reservable 0 Bps
Admin-groups: 0x00000000
Adj SID: 16 (unprotected) 17 (protected)
Link[1]: local address 10.10.21.1, remote address 10.10.21.2
Local node:
ISIS system ID: 0000.0000.0207 level-2 ASN: 1
Remote node:
TE router ID: 208.208.208.208
Host name: 920-R8
ISIS system ID: 0000.0000.0208 level-2 ASN: 1
Metric: IGP 10, TE 10, Latency 10
Bandwidth: Total 1250000000 Bps, Reservable 0 Bps
Admin-groups: 0x00000000
Adj SID: 18 (unprotected) 19 (protected)
Link[2]: local address 10.10.20.2, remote address 10.10.20.1
Local node:
ISIS system ID: 0000.0000.0207 level-2 ASN: 1
Remote node:
TE router ID: 209.209.209.209
Host name: 920-R9
ISIS system ID: 0000.0000.0209 level-2 ASN: 1
Metric: IGP 40, TE 40, Latency 40
Bandwidth: Total 1250000000 Bps, Reservable 0 Bps
Admin-groups: 0x00000052
Adj SID: 20 (unprotected) 22 (protected)
SRLG Values: 25
Node 2
TE router ID: 209.209.209.209
Host name: 920-R9
ISIS system ID: 0000.0000.0209 level-1 ASN: 1
ISIS system ID: 0000.0000.0209 level-2 ASN: 1
Prefix SID:
ISIS system ID: 0000.0000.0209 level-1 ASN: 1 domain ID: 0
Prefix 209.209.209.209, label 16001 (regular), flags: N
ISIS system ID: 0000.0000.0209 level-1 ASN: 1 domain ID: 0
Prefix 209.209.209.209, label 18001 (strict), flags: N
ISIS system ID: 0000.0000.0209 level-2 ASN: 1 domain ID: 0
Prefix 209.209.209.209, label 16001 (regular), flags: N
ISIS system ID: 0000.0000.0209 level-2 ASN: 1 domain ID: 0
Prefix 209.209.209.209, label 18001 (strict), flags: N
SRGB INFO:
ISIS system ID: 0000.0000.0209 level-1 ASN: 1
SRGB Start: 16000 Size: 8000
ISIS system ID: 0000.0000.0209 level-2 ASN: 1
SRGB Start: 16000 Size: 8000
Link[0]: local address 10.10.20.1, remote address 10.10.20.2
Local node:
ISIS system ID: 0000.0000.0209 level-2 ASN: 1
Remote node:
TE router ID: 207.207.207.207
Host name: 920-R7
ISIS system ID: 0000.0000.0207 level-2 ASN: 1
Metric: IGP 40, TE 40, Latency 40
Bandwidth: Total 1250000000 Bps, Reservable 0 Bps
Admin-groups: 0x00000052
Adj SID: 1980 (unprotected) 1981 (protected)
Link[1]: local address 10.10.22.1, remote address 10.10.22.2
Local node:
ISIS system ID: 0000.0000.0209 level-2 ASN: 1
Remote node:
TE router ID: 208.208.208.208
Host name: 920-R8
ISIS system ID: 0000.0000.0208 level-2 ASN: 1
Metric: IGP 10, TE 50, Latency 50
Bandwidth: Total 1250000000 Bps, Reservable 0 Bps
Admin-groups: 0x0000002C
Adj SID: 1971 (unprotected) 1972 (protected)
RP/0/RSP0/CPU0:ASR9K#
Further troubleshooting tips:
Enable the following debug commands on the PCCs:
debug segment-routing traffic-eng path
debug segment-routing traffic-eng pcalc
debug segment-routing traffic-eng policy
debug segment-routing traffic-eng topology
debug segment-routing traffic-eng ha
Enable the following debug commands on the PCE:
debug pce pcep
debug pce cspf
debug pce cspf-internal
debug pce error
debug pce path
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