Login
- Table of Contents
- Related Documents
-
| Title | Size | Download |
|---|---|---|
| 05-SR-MPLS Troubleshooting Guide | 281.45 KB |
Troubleshooting segment routing
SRv6 TE policy issues
SRv6 TE policy cannot take effect
Symptom
The output of the ping srv6-te policy command shows that an SRv6 TE policy cannot forward packets properly. For example:
<Sysname> ping srv6-te policy policy-name p1
The SRv6-TE policy does not reference a SID list or the referenced SID list is down.
Common causes
The following are the common causes of this type of issue:
· The SRv6 TE policy is shut down administratively.
· The BSID configuration of the SRv6 TE policy is incorrect or has conflicts.
· Some configuration for the SRv6 TE policy is missing.
· The number of SRv6 TE policies has exceeded the limit.
· The number of SIDs in the segment list has exceeded the limit.
· The SID list of the SRv6 TE policy differs from the planned packet forwarding path.
· Physical link faults have occurred on the forwarding path of the SRv6 TE policy.
Troubleshooting flow
Figure 1 shows the troubleshooting flowchart.
Figure 1 Troubleshooting flowchart
Solution
To resolve the issue:
1. On the source node of the SRv6 TE policy, execute the display segment-routing ipv6 te policy status command to view the reason why the SRv6 TE policy does not take effect.
<Sysname> display segment-routing ipv6 te policy status
Name/ID: p1/0
Status: Down
Check admin status : Failed
Check for endpoint & color : Passed
Check for segment list : Passed
Check valid candidate paths : Failed
Check for BSIDs : -
If the Check admin status field displays Failed, the SRv6 TE policy has been administratively shut down. Execute the undo shutdown command in SRv6 TE policy view to bring the policy up.
After the SRv6 TE policy is administratively up, execute the display segment-routing ipv6 te policy status command again to identify other fields displaying Failed or a hyphen (-). If the Check for segment List field displays as Failed, proceed to the following step.
2. Verify that no conflict occurs with the BSID of the SRv6 TE policy.
Execute the display segment-routing ipv6 te policy command at the source node of the SRv6 TE policy. If the Request state field displays Failed, it indicates a BSID request failure. The statically specified BSID might not be within the locator range or it might be duplicated with the BSID of an existing SRv6 TE policy, causing the SRv6 TE policy to become invalid. As a best practice, execute the undo binding-sid command for the invalid SRv6 TE policy to delete the statically specified BSID. The system will automatically allocate a BSID to prevent errors and conflicts.
<Sysname> display segment-routing ipv6 te policy
Name/ID: p1/0
Color: 10
Endpoint: 1000::1
Name from BGP:
BSID:
Mode: Dynamic Type: Type 2 Request state: Succeeded
Current BSID: 8000::1 Explicit BSID: - Dynamic BSID: 8000::1
Reference counts: 3
Flags: A/BS/NC
If the issue persists after the successful BSID allocation, proceed to the following step.
3. Verify that the SRv6 TE policy configuration is complete.
Assume that IS-IS is used to advertise SIDs. On the source node of the SRv6 TE policy, execute the display current-configuration command to view the current configuration of the SRv6 TE policy. Compare the configuration with the configuration in the following example. If any configuration item is missing, it indicates that the policy configuration is incomplete.
isis 1
address-family ipv6 unicast
segment-routing ipv6 locator a
segment-routing ipv6
locator a ipv6-prefix 1000:0:0:1:: 64 static 16
traffic-engineering
srv6-policy locator a
segment-list sl1
index 10 ipv6 1000::2:0:0:1:0
index 20 ipv6 1000::2:0:0:1:3
policy p1
color 100 end-point ipv6 4::4
candidate-paths
preference 100
explicit segment-list sl1
On each node along the SRv6 TE policy forwarding path, you must execute the segment-routing ipv6 locator command in IGP view in order to advertise the locator. For example:
isis 1
address-family ipv6 unicast
segment-routing ipv6 locator b
If the configuration is incomplete, supplement the missing parts. If the configuration is fully completed but the problem persists, proceed to the following step.
4. Verify that the number of SRv6 TE policies and that of segment lists do not exceed the limit.
Execute the display segment-routing ipv6 te policy statistics command on the source node of the SRv6 TE policy to identify whether the number of resources used by SRv6 TE policies has reached the limit.
<Sysname> display segment-routing ipv6 te policy statistics
IPv6 TE Policy Database Statistics
…
SRv6-TE policy resource information:
Max resources: 1024
Used resources: 1
Upper threshold: 512 (50%)
Lower threshold: 102 (10%)
SID list resource information:
Max resources: 4096
Used resources: 1
Upper threshold: 3277 (80%)
Lower threshold: 1638 (40%)
…
¡ If the value of the Used resources field in SRv6-TE policy resource information is equal to the value of the Max resources field, the number of SRv6 TE policies might have exceeded the limit. In this case, delete the unnecessary SRv6 TE policies.
¡ If the value of the Used resources field in SID list resource information is equal to the value of the Max resources field, the number of segment lists might have exceeded the limit. In this case, delete the unnecessary segment lists.
¡ If the number of SRv6 TE policies and that of segment lists have not exceeded the limit, proceed to the following step.
5. Verify that the number of SIDs in the segment list does not exceed the limit.
Enter probe view on the source node of the SRv6 TE policy, and execute the display system internal segment-routing ipv6 te policy status command. In the command output, the MaxSIDs field value represents the maximum number of SIDs allowed in the segment list.
[Sysname-probe] display system internal segment-routing ipv6 te policy status
…
MaxGroupNidNum: 1024 MaxPolicyNidNum: 1024
MaxSeglistNidNum: 4096 MaxNexthopNidNum: 65535
MaxOutNum: 32 MaxEcmpNum: 16
MaxSIDs: 10
…
Execute the display segment-routing ipv6 te segment-list command. In the command output, the Nodes field indicates the number of SID nodes configured in the specified segment list.
<Sysname> display segment-routing ipv6 te segment-list
Total Segment lists: 1
Name/ID: A/1
Origin: CLI
Status: Up
Verification State: Down
Nodes: 11
…
If the number of configured SID nodes exceeds the maximum number of SIDs supported, delete unnecessary SID values in the segment list. If the number of configured SID nodes does not exceed the limit, proceed to the following step.
6. Verify that the configuration of the SID list is as planned.
Execute the display segment-routing ipv6 te segment-list command on the source node of the SRv6 TE policy to display SID list information. The SID values arranged from top to bottom represent nodes or links from near to far to the source node of the SRv6 TE policy. If the Status field displays Down, the locator to which the SID belongs has not been learned correctly. In this case, troubleshoot this issue as described in the OSPFv3 or IS-IS troubleshooting guide.
[Sysname] display segment-routing ipv6 te segment-list
Total Segment lists: 1
Name/ID: s1/1
Origin: CLI
Status: Down
Verification State: Down
Nodes : 3
Index : 10 SID: 1::1
Status : UP TopoStatus: Nonexistent
Type : Type_2 Flags: None
Coc Type : - Common prefix length: 0
Index : 20 SID: 1::2
Status : Down TopoStatus: Nonexistent
Type : Type_2 Flags: None
Coc Type : - Common prefix length: 0
Index : 30 SID: 1::3
Status : Down TopoStatus: Nonexistent
Type : Type_2 Flags: None
Coc Type : - Common prefix length: 0
On each node along the SRv6 TE policy forwarding path, execute the display segment-routing ipv6 local-sid command in sequence to identify whether the SID values are consistent with those in the SID list displayed by the display segment-routing ipv6 te segment-list command. The SID types are usually End SID and End.X SID. For example, if the SID type is End SID, view SRv6 Local SID information.
[Sysname] display segment-routing ipv6 local-sid end
Local SID forwarding table (End)
Total SIDs: 2
SID : 1000::2:0:0:1:0/64
Function type : End Flavor : PSP
Locator name : b Allocation type: Dynamic
Owner : IS-IS-1 State : Active
Create Time : Sep 04 16:32:03.443 2021
If the SID list does not match the SID values of the nodes on the forwarding path, execute the undo index index-number command to delete the incorrect SID, and then run the index index-number ipv6 ipv6-address command to reconfigure the correct SID. If the SID list is consistent with the plan, proceed to the following step.
7. On each node along the SRv6 TE policy forwarding path, check the physical link state by using the display interface brief command. Ensure that both the physical state and the data link layer (DDL) protocol state of each interface are UP on the forwarding path. If the link is normal, or if the issue persists after link faults are removed, proceed to the following step.
8. If the issue persists, collect the following information and contact Technical Support:
¡ Results of each step.
¡ The configuration file, log messages, and alarm messages.
Related alarm and log messages
Alarm messages
N/A
Log messages
· SRPV6/2/SRPV6_BSID_CONFLICT
· SRPV6/2/SRPV6_BSID_CONFLICT_CLEAR
· SRPV6/5/SRPV6_PATH_STATE_DOWN
· SRPV6/4/SRPV6_POLICY_STATUS_CHG
· SRPV6/4/SRPV6_RESOURCE_EXDCEED
· SRPV6/4/SRPV6_RESOURCE_EXCEED_CLEAR
· SRPV6/5/SRPV6_SEGLIST_STATE_DOWN
· SRPV6/5/SRPV6_ SEGLIST_STATE_DOWN
· SRPV6/2/SRPV6_STATE_DOWN
· SRPV6/2/SRPV6_STATE_DOWN_CLEAR
The controller failed to set up SRv6 TE policy tunnels
Symptom
In the backbone network shown by Figure 2, the controller sets up and maintains SRv6 TE policy tunnels as follows:
1. The forwarding devices (including PE, P, and RR) exchange link topology and TE attribute information with each other through IGP routing.
2. The IGP running on the PEs advertises link topology and TE attribute information to BGP-LS.
3. The controller establishes a BGP-LS peer relationship with each PE, and collects link topology and TE attribute information through BGP-LS.
4. Based on the collected link topology and TE attribute information, the controller calculates an optimal SRv6 TE policy tunnel from PE 1 to PE 3, which will be used as the forwarding path between PE 1 and PE 3.
5. The controller advertises a BGP IPv6 SR policy route with the SRv6 TE policy to the RR, which then reflects it to PE 1.
6. On receipt of the SRv6 TE policy, PE 1 reports the status of the SRv6 TE policy status to the controller via BGP-LS for path maintenance.
Under normal circumstances, PE 1 should learn and create an SRv6 TE policy between PE 1 to PE 3 based on BGP IPv6 SR policy routes deployed from the controller. However, after you execute the display segment-routing ipv6 te policy command on PE 1, you cannot find any SRv6 TE policy tunnels or SRv6 TE policies created from the BGP routes of the controller.
Common causes
The following are the common causes of this type of issue:
· The controller cannot correctly learn link topology and TE attribute information through BGP-LS, which prevents SRv6 TE Policy calculation. Possible causes include:
¡ The BGP-LS peer relationship between the controller and a PE is in an abnormal state.
¡ The IGP failed to advertise link topology information to BGP-LS. The network type of the related IGP links is not P2P and those links do not support BGP-LS auto-discovery.
¡ The IGP did not advertise link TE attribute information or advertised incorrect link TE attribute information.
¡ The IPv6 TE router ID in the BGP-LS NLRI is not unique.
· After receiving BGP IPv6 SR policy routes from the controller, the RR failed to reflect those routes to PE 1. Possible causes include:
¡ The BGP IPv6 SR policy peer relationship between the RR and PE 1 is in an abnormal state.
¡ The BGP IPv6 SR policy routes were filtered out.
Troubleshooting flow
Figure 3 shows the troubleshooting flowchart.
Figure 3 Troubleshooting flowchart
Solution
1. On the source node (PE 1) of the SRv6 TE policy, execute the display segment-routing ipv6 te policy command to identify whether the SRv6 TE policy is established correctly. Under normal circumstances, the following information should be displayed for an SRv6 TE policy established through BGP:
¡ The BGP paths field displays the number of candidate paths established by BGP. If this field displays 0, no candidate paths are established by BGP.
¡ If the ProtoOrigin field displays BGP for a candidate path, the candidate path was generated by BGP. If this field does not display BGP, the candidate path was not generated by BGP.
<PE1> display segment-routing ipv6 te policy
Name/ID: test1/0
Color: 10
End-point: 3::3
Name from BGP: test1
Name from PCE:
…
Candidate paths statistics:
CLI paths: 0 BGP paths: 2 PCEP paths: 0 ODN paths: 0
Preference : 100
Network slice ID: -
CPathName: test1
CPathPolicyName:
ProtoOrigin: BGP Discriminator: 100
…
Preference : 200
Network slice ID: -
CPathName: test1
CPathPolicyName:
ProtoOrigin: BGP Discriminator: 200
…
If the display segment-routing ipv6 te policy command has no output, or if the above fields do not meet expectations, no SRv6 TE policies were advertised by BGP. In this case, proceed to the following step.
2. Identify whether the controller has correctly established a BGP-LS peer relationship with PE 1.
On PE 1, execute the display bgp peer link-state command to check the BGP-LS peer state of the controller. If the State field displays Established for the controller, PE 1 has established a BGP-LS peer relationship with the controller correctly. If the State field does not display Established, the peer relationship between the controller and PE 1 is in an abnormal state. In this case, troubleshoot this issue as described in "BGP session unable to enter Established state" in BGP Troubleshooting Guide.
<PE1> display bgp peer link-state
BGP local router ID: 1.1.1.1
Local AS number: 100
Total number of peers: 1 Peers in established state: 1
* - Dynamically created peer
Peer AS MsgRcvd MsgSent OutQ PrefRcv Up/Down State
4::4 100 1504 1609 0 2 22:26:58 Established
If the peer relationship between the controller and PE 1 is in Established state and the issue still persists, proceed to the following step.
3. Identify whether the IGP has advertised link topology information to BGP-LS.
On PE 1, execute the display bgp link-state command to identify whether its BGP-LS link information is correct. In a backbone network, the Network field should display the following link information type codes:
¡ V: Network node information.
¡ E: Network link information.
¡ T6: Network IPv6 prefix information.
¡ T4: Network IPv4 prefix information.
¡ TEPOLICY: SRv6 TE policy information in the network.
¡ SD: SRv6 SID information in the network.
Identify whether all nodes, links, prefixes, SRv6 SIDs, and SRv6 TE policies are completely included in the BGP LS information.
<PE1> display bgp link-state
Total number of routes: 39
BGP local router ID is 1.1.1.1
Status codes: * - valid, > - best, d - dampened, h - history,
s - suppressed, S - stale, i - internal, e - external
a - additional-path
Origin: i - IGP, e - EGP, ? - incomplete
Prefix codes: E link, V node, T4 IPv4 route, T6 IPv6 route, SD SRv6 SID desc
u/U unknown,
I Identifier, N local node, R remote node, L link, P prefix,
L1/L2 ISIS level-1/level-2, O OSPF, O3 OSPFv3,
D direct, S static, B BGP, SS SRv6 SID,
a area-ID, l link-ID, t topology-ID, s ISO-ID,
c confed-ID/ASN, b bgp-identifier, r router-ID,
i if-address, n peer-address, o OSPF Route-type, p IP-prefix
d designated router address/interface, ID Link Descriptor Identifer
* > Network : [V][L2][I0x0][N[c100][b1.1.1.1][s0000.0000.0001.00]]/328
NextHop : 0.0.0.0 LocPrf :
PrefVal : 32768 OutLabel : NULL
MED :
Path/Ogn: i
* > Network : [E][L2][I0x0][N[c100][b1.1.1.1][s0000.0000.0001.00]][R[c100][b1.1.1.1][s0000.0000.0002.00]][L[i12::1][n12::2]]/888
NextHop : 0.0.0.0 LocPrf :
PrefVal : 32768 OutLabel : NULL
MED :
Path/Ogn: i
* > Network : [T6][L2][I0x0][N[c100][b1.1.1.1][s0000.0000.0001.00]][P[p12::/120]]/488
NextHop : 0.0.0.0 LocPrf :
PrefVal : 32768 OutLabel : NULL
MED :
Path/Ogn: i
* > Network : [T6][L2][I0x0][N[c100][b1.1.1.1][s0000.0000.0002.00]][P[p200:A:B:C::/64]]/432
NextHop : 0.0.0.0 LocPrf :
PrefVal : 32768 OutLabel : NULL
MED :
Path/Ogn: i
* > Network : [TEPOLICY][SEGMENT-ROUTING][I0x0][N[c100][bgp-ls-identifier1.1.1.1][bgp-router-id1.1.1.1][ipv4-router-id0.0.0.0][ipv6-router-id1::1]][TE[protocol-origin2][Flag192][endpoint3::3][color10][originator-as100][originator-address4::4][discriminator100]]/952
NextHop : 0.0.0.0 LocPrf :
PrefVal : 32768 OutLabel : NULL
MED :
Path/Ogn: i
* > Network : [SD][L2][I0x0][N[c100][b1.1.1.1][s0000.0000.0001.00]][SS100:A:B:C:0:1::]/488
NextHop : 0.0.0.0 LocPrf :
PrefVal : 32768 OutLabel : NULL
MED :
Path/Ogn: i
* > Network : [SD][L2][I0x0][N[c100][b1.1.1.1][s0000.0000.0002.00]][SS200:A:B:C:0:1::]/488
NextHop : 0.0.0.0 LocPrf :
PrefVal : 32768 OutLabel : NULL
MED :
Path/Ogn: i
……
If node-type BGP LS information is incomplete, the IGP configuration on PE 1 might be incomplete, which prevents the IGP from advertising link topology information to BGP-LS.
¡ If the IGP is IS-IS, execute the distribute bgp-ls command in IS-IS view to advertise the link topology information collected by IS-IS to BGP-LS.
¡ If the IGP is OSPFv3, execute the distribute bgp-ls command in OSPFv3 view to advertise the link topology information collected by OSPFv3 to BGP-LS.
4. Identify whether the network type of the related IGP links is P2P.
Execute the display this command on each IGP-enabled interface for all PE and P devices to check for non-P2P IGP links. If the network type of an IGP link is not P2P, it does not support BGP-LS link auto-discovery.
¡ For IS-IS, execute the isis circuit-type p2p command on the faulty interface to change its network type to P2P.
¡ For OSPFv3, execute the ospfv3 network-type p2p command on the faulty interface to change its network type to P2P.
[Sysname-GigabitEthernet1/0/1] disp this
#
interface GigabitEthernet1/0/1
isis ipv6 enable 1
isis circuit-type p2p
isis link-delay average 10
mpls te enable
ipv6 address 12::1/120
#
If the network type of all IGP links is P2P and the issue still persists, proceed to the following step.
5. Identify whether the IGP did not advertise link TE attribute information or advertised incorrect link TE attribute information.
On PE 1, execute the display bgp link-state command to view detailed information about a link and identify whether the link attribute information displayed by the LS field is complete.
[PE1] display bgp link-state [E][L2][I0x0][N[c100][b1.1.1.1][s0000.0000.0001.00]]
[R[c100][b1.1.1.1][s0000.0000.0002.00]][L[i12::1][n12::2]]/888
BGP local router ID: 1.1.1.1
Local AS number: 100
Paths: 1 available, 1 best
BGP LS information of [E][L2][I0x0][N[c100][b1.1.1.1][s0000.0000.0001.00]][R[c100][b1.1.1.1][s0000.0000.0002.00]][L[i12::1][n12::2]]/888:
Imported route.
Original nexthop: 0.0.0.0
Out interface : NULL0
Route age : 04h22m11s
OutLabel : NULL
LS : TE maximum bandwidth (kbits/sec): 0, TE maximum reservable b
andwidth (kbits/sec): 0, TE unreserved bandwidth (kbits/sec)
: 0 0 0 0 0 0 0 0, TE Metric: 10, Metric: 10 SRv6 End.X SID:
100:A:B:C:0:1:3:0, function Type=End.X with PSP, algorithm=
0, weight=0, flags(B/S/P/C)=0/0/0/0 SRv6 End.X SID: 100:A:B:
C:0:1:4:0, function Type=End.X (NO-FLAVOR), algorithm=0, wei
ght=0, flags(B/S/P/C)=0/0/0/0 SRv6 End.X SID: 100:A:B:C:0:1:
5:0, function Type=End.X with PSP, USP & USD, algorithm=0, w
eight=0, flags(B/S/P/C)=0/0/0/0 Delay flag:0, Average delay:
10, Link loss flag: 0, Link loss: 0.000003%
RxPathID : 0x0
TxPathID : 0x0
Org-validation : Valid
AS-path : (null)
Origin : igp
Attribute value : pref-val 32768
State : valid, local, best
IP precedence : N/A
QoS local ID : N/A
Traffic index : N/A
If the displayed link TE attribute information is incomplete, the controller might collect topology link information incompletely, which will cause incorrect path calculation results. To ensure correct TE attribute advertisement in this case, perform the following operations:
¡ Execute the mpls te command in system view to enable MPLS TE.
¡ Execute the mpls te enable command on the interface announced by the IGP to enable the MPLS TE capability.
¡ For IS-IS, execute the te attribute enable command in IS-IS view to have IS-IS advertises link attributes. Meanwhile, execute the advertise link-attributes or router-id command in IS-IS IPv6 address family view to ensure that link attributes are advertised correctly, supporting the topology auto-discovery function of BGP-LS.
¡ For OSPFv3, execute the router-id or te-router-id command in OSPFv3 view to support the topology auto-discovery function of BGP-LS.
If the above configurations are correct and the issue still persists, proceed to the following step.
6. Identify whether the IPv6 TE router ID in the BGP-LS NLRI is unique.
As the source node of the SRv6 TE policy, PE 1 must report SRv6 TE policy status information to the controller through BGP-LS, so that the controller can maintain and update the forwarding paths accordingly. To achieve this goal, you must execute the distribute bgp-ls command in SRv6 TE view.
If the IPv6 TE router ID is unique across the network and the issue still persists, proceed to the following step.
7. Identify whether the BGP IPv6 SR policy peer relationships among the PEs, RR, and the controller are established correctly.
The controller and PEs are clients of the RR. On the PEs and RR, execute the display bgp peer ipv6 sr-policy command to check their BGP IPv6 SR policy peer states. If the State field displays Established, the BGP IPv6 SR policy peer relationship is established correctly. If the State field does not display Established, the BGP IPv6 SR policy peer relationship is established incorrectly. In this case, troubleshoot this issue as described in “BGP session unable to enter Established state” in BGP Troubleshooting Guide.
[PE1] display bgp peer ipv6 sr-policy
BGP local router ID: 1.1.1.1
Local AS number: 100
Total number of peers: 1 Peers in established state: 1
* - Dynamically created peer
Peer AS MsgRcvd MsgSent OutQ PrefRcv Up/Down State
4::4 100 1596 1704 0 2 23:49:58 Established
If the BGP IPv6 SR policy peer relationships are established correctly, and the issue still persists, proceed to the following step.
8. Identify whether the related BGP IPv6 SR policy routes are filtered out on the RR.
On the RR, execute the display this command in BGP IPv6 SR policy view to identify whether routing policies are used to filter routes. Verify that BGP IPv6 SR policy routes can be reflected to PE 1 correctly.
[RR-bgp-default-srpolicy-ipv6] disp this
#
#
address-family ipv6 sr-policy
peer 2::2 enable
peer 2::2 reflect-client
peer 3::3 enable
peer 3::3 reflect-client
peer 4::4 enable
If BGP IPv6 SR policy routes are not filtered and are reflected to PE 1 correctly, execute the display bgp routing-table ipv6 sr-policy command to view BGP IPv6 SR policy route entries. For example, [100][10][3::3] indicates that the candidate path priority, color value, and endpoint node of the SRv6 TE policy is 100, 10, and 3::3, respectively. The route entry is valid and optimal.
[PE1] display bgp routing-table ipv6 sr-policy
Total number of routes: 2
BGP local router ID is 1.1.1.1
Status codes: * - valid, > - best, d - dampened, h - history,
s - suppressed, S - stale, i - internal, e - external
a - additional-path
Origin: i - IGP, e - EGP, ? - incomplete
* >i Network : [100][10][3::3]/192
NextHop : 4::4 LocPrf : 100
PrefVal : 0 OutLabel : NULL
MED : 0
Path/Ogn: i
* >i Network : [200][10][3::3]/192
NextHop : 4::4 LocPrf : 100
PrefVal : 0 OutLabel : NULL
MED : 0
Path/Ogn: i
If BGP IPv6 SR policy routes are filtered out by a routing policy, execute the route-policy command in system view to edit the routing policy. If BGP IPv6 SR policy routes are not filtered and PE 1 still cannot learn BGP IPv6 SR policy routes, proceed to the following step.
9. If the issue persists, collect the following information and contact Technical Support:
¡ Results of each step.
¡ The configuration file, log messages, and alarm messages.
Related alarm and log messages
Alarm messages
N/A
Log messages
· SRPV6/2/SRPV6_BSID_CONFLICT
· SRPV6/2/SRPV6_BSID_CONFLICT_CLEAR
· SRPV6/5/SRPV6_PATH_STATE_DOWN
· SRPV6/4/SRPV6_POLICY_STATUS_CHG
· SRPV6/4/SRPV6_RESOURCE_EXDCEED
· SRPV6/4/SRPV6_RESOURCE_EXCEED_CLEAR
· SRPV6/5/SRPV6_SEGLIST_STATE_DOWN
· SRPV6/5/SRPV6_ SEGLIST_STATE_DOWN
· SRPV6/2/SRPV6_STATE_DOWN
· SRPV6/2/SRPV6_STATE_DOWN_CLEAR
DSCP-based traffic steering to an SRv6 TE policy failed
Symptom
In the backbone network shown by Figure 4, an SRv6 TE policy group is deployed between PE 1 (source node) and PE 3 (destination node). The SRv6 TE policy group performs DSCP-based traffic steering. Under normal circumstances, VPN traffic with a DSCP value of 10 is forwarded through SRv6 TE policy A, and VPN traffic with a DSCP value of 20 is forwarded through SRv6 TE policy B.
PE 1 is configured with a QoS policy that performs the following actions:
· Sets the DSCP value to 10 for VPN traffic with source address 11.11.11.11/32 and destination address 22.22.22.22/32.
· Sets the DSCP value to 20 for VPN traffic with source address 10.10.10.10/32 and destination address 20.20.20.20/32.
Although traffic with a DSCP value to 10 is not forwarded through SRv6 TE policy A, packets with a DSCP value of 10 are found on multiple directly-connected output interfaces of PE 1.
Common causes
The following are the common causes of this type of issue:
· The SRv6 TE policy group is in Down state and cannot be used for traffic forwarding.
· Traffic is not steered to the SRv6 TE policy group for further forwarding.
· The SRv6 TE policy group is configured with incorrect DSCP mappings.
Troubleshooting flow
Figure 5 shows the troubleshooting flowchart.
Figure 5 Troubleshooting flowchart
Solution
1. Check the status of the SRv6 TE policy group.
On the source node (PE 1) of the SRv6 TE policy, execute the display segment-routing ipv6 te policy-group verbose command to identify whether the status of the SRv6 TE policy group is Up. Under normal circumstances, the GroupState field should display Up, indicating that the SRv6 TE policy group is in normal state. The Group type field should display Static DSCP or Dynamic DSCP, indicating that the SRv6 TE policy group performs DSCP-based traffic steering.
<PE1> display segment-routing ipv6 te policy-group verbose
Total number of policy groups: 1
GroupID: 10 GroupState: Up
GroupNID: 2151677953 Referenced: 1
Flags: None Group type: Static DSCP
Group color: 100
StateChangeTime: 2024-04-23 16:22:03
Endpoint: 3::3
BSID:
Explicit BSID: - Request state: -
Best-effort NID: 2160066561
Drop upon mismatch: Disabled
UP/Total Mappings: 3/3
IPv4 Best-effort: Configured IPv6 Best-effort: Not configured
Color Type DSCP
10 IPv4 10
20 IPv4 20
Best-effort IPv4 default
If the GroupState field displays Down, execute the display segment-routing ipv6 te policy-group last-down-reason command to identify the cause of this status.
<PE1> display segment-routing ipv6 te policy-group last-down-reason
Group ID : 1 Group type : Static DSCP
Group color: 100 Endpoint : 3::3
Group NID : 2151677953
Created at : 2024-04-23 15:31:44
Up time : 2024-04-23 15:31:55
Down time : 2024-04-23 15:31:44
Down reason: No endpoint
Color: 10
Up time : 2024-04-23 15:31:50
Down time : 2024-04-23 15:31:44
Down reason: SRv6-TE policy down
Color: 20
Up time : 2024-04-23 15:31:55
Down time : 2024-04-23 15:31:44
Down reason: SRv6-TE policy down
You can identify the cause based on the Down reason field as follows:
¡ If the Down reason field displays No endpoint, the SRv6 TE policy group lacks destination node address configuration. In this case, execute the end-point ipv6 command in SRv6 TE policy group view to specify the loopback interface address of PE 3 as the destination node. ODN-created SRv6 TE policy groups do not require this manual configuration.
¡ If the Down reason field displays No color-DSCP mappings, the SRv6 TE policy group lacks color-to-DSCP mappings.
- For static SRv6 TE policy groups, execute the color match dscp command in SRv6 TE policy group view to configure color-to-DSCP mappings as needed.
- For ODN-created SRv6 TE policy groups, execute the color match dscp command in DSCP forward type view to configure color-to-DSCP mappings as needed.
¡ If the Down reason field displays No active SRv6-TE policies, the SRv6 TE policy group does not have valid SRv6 TE policies. In this case, troubleshoot this issue as described in “SRv6 TE policy cannot take effect” or “The controller failed to set up SRv6 TE policy tunnels.”
¡ If the Down reason field displays Forwarding down, no usable forwarding entries exist. This might occur due to insufficient forwarding resources. In this case, troubleshoot this issue as described in step 4.
If the SRv6 TE policy group is normal state and the issue still persists, proceed to the following step.
2. Identify whether the related VPN routes are recursed correctly.
On PE 1, execute the display bgp routing-table ipv4 vpn-instance command to view detailed information about VPN route 22.22.22.22/32 advertised by PE 3. Under normal circumstances, the Rely tunnel IDs field should display 2151677953 for the VPN route, which is the same as the GroupNID of the SRv6 TE policy group in the output of the display segment-routing ipv6 te policy-group verbose command.
<PE1> display bgp routing-table ipv4 vpn-instance vpn1 22.22.22.22
BGP local router ID: 1.1.1.1
Local AS number: 100
Paths: 1 available, 1 best
BGP routing table information of 22.22.22.22/32:
From : 3::3 (3.3.3.3)
Rely nexthop : FE80::A2C3:E2FF:FEB5:306
Original nexthop: 3::3
Out interface : GigabitEthernet1/0/2
Route age : 00h17m14s
OutLabel : 3
Ext-Community : <RT: 100:1>, <CO-Flag:Color(00:100)>
RxPathID : 0x0
TxPathID : 0x0
PrefixSID : End.DT4 SID <300:1::1:2>
SRv6 Service TLV (37 bytes):
Type: SRV6 L3 Service TLV (5)
Length: 34 bytes, Reserved: 0x0
SRv6 Service Information Sub-TLV (33 bytes):
Type: 1 Length: 30, Rsvdl: 0x0
SID Flags: 0x0 Endpoint behavior: 0x13 Rsvd2: 0x0
SRv6 SID Sub-Sub-TLV:
Type: 1 Len: 6
BL: 64 NL: 0 FL: 64 AL: 0 TL: 0 TO: 0
AS-path : 300
Origin : incomplete
Attribute value : MED 0, localpref 100, pref-val 0
State : valid, internal, best, remoteredist
Source type : evpn remote-import
IP precedence : N/A
QoS local ID : N/A
Traffic index : N/A
Tunnel policy : a
Rely tunnel IDs : 2151677953
If the Rely tunnel IDs field is blank or displays a value different from the GroupNID of the SRv6 TE policy group, the recursive tunnel is incorrect for the VPN route. In this case, execute the display current-configuration | begin bgp command on PE 1 to identify whether the VPN route recursion configuration of BGP includes the segment-routing ipv6 traffic-engineering command. If the PEs exchange VPN routes over EVPN, both the segment-routing ipv6 traffic-engineering and segment-routing ipv6 locator commands require specifying the evpn keyword.
#
ip vpn-instance vpna
peer 10.1.1.2 as-number 65410
#
address-family ipv4 unicast
segment-routing ipv6 traffic-engineering best-effort
segment-routing ipv6 locator aaa
peer 10.1.1.2 enable
If the above route recursion configuration is correct, identify whether the configuration that defines route recursion to the SRv6 TE policy group is correct. In this example, VPN routes are recursed to SRv6 TE policy groups based on their color values.
If the color value of a BGP route matches that of an SRv6 TE policy group, and the next hop of the BGP route is the same as the endpoint node of the SRv6 TE policy group, the route can be recursed to the SRv6 TE policy group. If this method is used to achieve route recursion, execute the display bgp routing-table ipv4 vpn-instance command on PE 1 to view detailed information about VPN route 22.22.22.22/32 advertised by PE 3, and then identify whether the color value displayed at the Ext-Community field is the same as that of the SRv6 TE policy group. In this example, the color value is 100.
<PE1> display bgp routing-table ipv4 vpn-instance vpn1 22.22.22.22
BGP local router ID: 1.1.1.1
Local AS number: 100
Paths: 1 available, 1 best
BGP routing table information of 22.22.22.22/32:
From : 3::3 (3.3.3.3)
Rely nexthop : FE80::A2C3:E2FF:FEB5:306
Original nexthop: 3::3
Out interface : GigabitEthernet1/0/2
Route age : 00h17m14s
OutLabel : 3
Ext-Community : <RT: 100:1>, <CO-Flag:Color(00:100)>
RxPathID : 0x0
TxPathID : 0x0
PrefixSID : End.DT4 SID <300:1::1:2>
SRv6 Service TLV (37 bytes):
Type: SRV6 L3 Service TLV (5)
Length: 34 bytes, Reserved: 0x0
SRv6 Service Information Sub-TLV (33 bytes):
Type: 1 Length: 30, Rsvdl: 0x0
SID Flags: 0x0 Endpoint behavior: 0x13 Rsvd2: 0x0
SRv6 SID Sub-Sub-TLV:
Type: 1 Len: 6
BL: 64 NL: 0 FL: 64 AL: 0 TL: 0 TO: 0
AS-path : 300
Origin : incomplete
Attribute value : MED 0, localpref 100, pref-val 0
State : valid, internal, best, remoteredist
Source type : evpn remote-import
IP precedence : N/A
QoS local ID : N/A
Traffic index : N/A
Tunnel policy : a
Rely tunnel IDs : 2151677953
If the BGP route carries a different color attribute or it does not carry a color attribute, execute the route-policy and apply extcommunity color command to configure the desired color attribute value, and then apply the related routing policy to the PEs.
#
bgp 100
#
address-family vpnv4
peer 3::3 enable
peer 3::3 route-policy a export
peer 3::3 prefix-sid
#
#
route-policy a permit node 10
apply extcommunity color 00:100 additive
#
If the related VPN routes are recursed correctly and the issue still persists, proceed to the following step.
3. Check for incorrect color-to-DSCP mappings in the SRv6 TE policy group.
On PE 1, execute the display segment-routing ipv6 te policy-group verbose command to check for incorrect color-to-DSCP mappings in the SRv6 TE policy group.
<PE1> display segment-routing ipv6 te policy-group verbose
Total number of policy groups: 1
GroupID: 10 GroupState: Up
GroupNID: 2151677953 Referenced: 1
Flags: None Group type: Static DSCP
Group color: 100
StateChangeTime: 2024-04-23 16:22:03
Endpoint: 3::3
BSID:
Explicit BSID: - Request state: -
Best-effort NID: 2160066561
Drop upon mismatch: Disabled
UP/Total Mappings: 3/3
IPv4 Best-effort: Configured IPv6 Best-effort: Not configured
Color Type DSCP
10 IPv4 10
20 IPv4 20
Best-effort IPv4 default
According to the above command output:
¡ IPv4 VPN traffic with a DSCP value of 10 is forwarded through the SRv6 TE policy with a color value of 10.
¡ IPv4 VPN traffic with a DSCP value of 20 is forwarded through the SRv6 TE policy with a color value of 20.
If the above mappings are incorrect, perform one of the following operations as needed:
¡ For static SRv6 TE policy groups, execute the color match dscp command in SRv6 TE policy group view to edit color-to-DSCP mappings as needed.
¡ For ODN-created SRv6 TE policy groups, execute the color match dscp command in DSCP forward type view to edit color-to-DSCP mappings as needed.
If all color-to-DSCP mappings are correct in the SRv6 TE policy group and the issue still persists, proceed to the following step.
4. If the issue persists, collect the following information and contact Technical Support:
¡ Results of each step.
¡ The configuration file, log messages, and alarm messages.
Related alarm and log messages
Alarm messages
N/A
Log messages
· SRPV6/2/SRPV6_BSID_CONFLICT
· SRPV6/2/SRPV6_BSID_CONFLICT_CLEAR
· SRPV6/5/SRPV6_PATH_STATE_DOWN
· SRPV6/4/SRPV6_POLICY_STATUS_CHG
· SRPV6/4/SRPV6_RESOURCE_EXDCEED
· SRPV6/4/SRPV6_RESOURCE_EXCEED_CLEAR
· SRPV6/5/SRPV6_SEGLIST_STATE_DOWN
· SRPV6/5/SRPV6_ SEGLIST_STATE_DOWN
· SRPV6/2/SRPV6_STATE_DOWN
· SRPV6/2/SRPV6_STATE_DOWN_CLEAR
Failure to trigger SRv6 BE-based forwarding
Symptom
In the SRv6 backbone network shown by Figure 6, VPN traffic is forwarded through the SRv6 TE policy deployed between PE 1 and PE 3. When the SRv6 TE policy fails, traffic cannot be switched to SRv6 BE mode, which results in service interruption and packet loss.
According to the output of the display ip routing-table vpn-instance command on PE 1, the related VPN routing table lacks VPN route 2.2.2.2/32.
[PE1] display ip routing-table vpn-instance vpna
Destinations : 6 Routes : 6
Destination/Mask Proto Pre Cost NextHop Interface
1.1.1.1/32 BGP 255 0 10.1.1.2 GE0/0/1
10.1.1.0/24 Direct 0 0 10.1.1.1 GE0/0/1
10.1.1.1/32 Direct 0 0 127.0.0.1 GE0/0/1
10.1.1.255/32 Direct 0 0 10.1.1.1 GE0/0/1
127.0.0.0/8 Direct 0 0 127.0.0.1 InLoop0
255.255.255.255/32 Direct 0 0 127.0.0.1 InLoop0
Common causes
The following are the common causes of this type of issue:
· The BGP route recursion method is incorrect.
Troubleshooting flow
Figure 7 shows the troubleshooting flowchart.
Figure 7 Troubleshooting flowchart
Solution
1. Identify whether the BGP VPNv4 or BGP EVPN routes transmitted between PE 1 and PE 3 are valid.
On PE 1, execute the display bgp routing-table vpnv4 or display bgp l2vpn evpn command to identify whether the related VPN routes is valid and optimal. For example, if the * and > markers are not displayed for BGP VPNv4 route 2.2.2.2/32 is neither valid nor optimal.
[PE1] display bgp routing-table vpnv4
BGP local router ID is 1.1.1.1
Status codes: * - valid, > - best, d - dampened, h - history,
s - suppressed, S - stale, i - internal, e - external
a - additional-path
Origin: i - IGP, e - EGP, ? - incomplete
Total number of VPN routes: 4
Total number of routes from all PEs: 2
Route distinguisher: 100:1(vpna)
Total number of routes: 4
Network NextHop MED LocPrf PrefVal Path/Ogn
* >e 1.1.1.1/32 10.1.1.2 0 0 65410i
i 2.2.2.2/32 4::4 0 100 0 65420i
* >e 10.1.1.0/24 10.1.1.2 0 0 65410?
i 10.2.1.0/24 4::4 0 100 0 65420?
Execute the display this command in BGP-VPN IPv4 view to check for incorrect VPN route recursion settings. Under normal circumstances, the route recursion settings are as follows:
[PE1-bgp-default-vpna] disp this
#
#
ip vpn-instance vpna
peer 10.1.1.2 as-number 65410
#
address-family ipv4 unicast
segment-routing ipv6 traffic-engineering best-effort
segment-routing ipv6 locator aaa
peer 10.1.1.2 enable
#
If the segment-routing ipv6 traffic-engineering best-effort command is executed, the device preferentially steers traffic to SRv6 TE policies for further forwarding. If the related SRv6 TE policy fails, traffic will be forwarded in SRv6 BE mode.
If the VPN route recursion settings are correct and the issue still persists, proceed to the following step.
2. If the issue persists, collect the following information and contact Technical Support:
¡ Results of each step.
¡ The configuration file, log messages, and alarm messages.
Related alarm and log messages
Alarm messages
N/A
Log messages
N/A
