SR Policy: source address is not specified

[Yvan.hua]

I built the test environment as shown, R1-R6 configures MPLS and Segment Routing. At present, CE-R7 PING CE-R8 is normal, the outer label is the SID instead of the LDP distribution label, R1-R6 Loopback's SID Troune 16100-16600.
Then I tried to configure SR Policy and found the following tips.(Cisco IOS XE Software, Version 16.12.05)

What is the problem?

(sorry for my poor English)

---------------------------------------------------------------------

R3#show segment-routing traffic-eng policy all

Name: sr35142 (Color: 10 End-point: 6.6.6.6)
Status:
Admin: up, Operational: down for 04:40:59 (since 07-19 02:03:51.590)
Candidate-paths:
Preference 10:
Explicit: segment-list sr35142 (inactive)
Inactive Reason: source address is not specified
Weight: 10, Metric Type: TE
Attributes:
Binding SID: 29
Allocation mode: dynamic
State: Programmed

----------------------------------------------------------------------------------------------------------

router isis
net 49.0000.0000.0000.0003.00
is-type level-2-only
metric-style wide
log-adjacency-changes

distribute link-state
segment-routing mpls

!

!

segment-routing mpls
!
set-attributes
address-family ipv4
sr-label-preferred
exit-address-family
!
!
connected-prefix-sid-map
address-family ipv4
3.3.3.3/32 index 300 range 1
exit-address-family
!
!
segment-routing traffic-eng
segment-list name sr35142
index 10 mpls label 16500
index 20 mpls label 16100
index 30 mpls label 16200
!
policy sr35142
color 10 end-point 6.6.6.6
candidate-paths
preference 10
explicit segment-list sr35142 weight 10

!

CE-R7#traceroute 192.168.8.1 source loopback 0 numeric
Type escape sequence to abort.
Tracing the route to 192.168.8.1
VRF info: (vrf in name/id, vrf out name/id)
1 37.1.1.3 0 msec 0 msec 0 msec
2 23.1.1.2 [MPLS: Labels 16600/28 Exp 0] 0 msec 0 msec 0 msec
3 68.1.1.6 [MPLS: Label 28 Exp 0] 4 msec 0 msec 0 msec
4 68.1.1.8 0 msec * 0 msec
CE-R7#

[loris.marcellini]

Hey, I found something similar, could you check whether this is of any
help:
https://community.cisco.com/t5/other-service-provider-subjects/sr-te-policy-in-ios-xe/td-p/4421231

[Yvan.hua]

I have seen this post, I didn't set up PCE / PCC, I don't quite clear whether this thing must be set, it is watching the relevant materials.

Cisco IOS Software [Gibraltar], ISR Software (X86_64_LINUX_IOSD-UNIVERSALK9-M), Version 16.12.5, RELEASE SO FTWARE (fc3)

I only found commands that open the PCC and didn't find the command of the PCE. The current interface is P2P mode, and "Distribute Link-State" is also set in the process of ISIS.

Thank you for your reply

[loris.marcellini]

Are the isis interfaces set up as p2p?

[Harold Ritter]

Hi @Yvan.hua ,

Add the following configuration under the policy preference. It should fix it.

policy sr35142
color 10 end-point 6.6.6.6
candidate-paths
preference 10

constraints
segments
dataplane mpls
explicit segment-list sr35142 weight 10

Regards,

[Yvan.hua]

Hi Harold

    thanks for your reply,

    I tried to do this, but I didn't fix this problem. Attached to some of my show information.

------------------------------------------------------------------------------

policy sr35142
color 10 end-point 6.6.6.6
candidate-paths
preference 10
explicit segment-list sr35142 weight 10
constraints
segments
dataplane mpls
!

R3# show seg tra po al de

Name: sr35142 (Color: 10 End-point: 6.6.6.6)
Status:
Admin: up, Operational: down for 23:14:39 (since 07-19 02:03:51.590)
Candidate-paths:
Preference 10:
Explicit: segment-list sr35142 (inactive)
Inactive Reason: source address is not specified
Weight: 10, Metric Type: TE
Attributes:
Binding SID: 29
Allocation mode: dynamic
State: Programmed
Forwarding-ID: 65536 (0x14)
Stats:
Packets: 0 Bytes: 0

Event history:
Timestamp Client Event type Context: Value
--------- ------ ---------- -------: -----
07-19 02:03:51.590 CLI AGENT Policy created Name: sr35142
07-19 02:03:51.590 CLI AGENT Set colour Colour: 10
07-19 02:03:51.590 CLI AGENT Set end point End-point: 6.6.6.6
07-19 02:03:51.591 CLI AGENT Set explicit path Path option: sr35142
07-19 02:16:31.251 CLI AGENT Set explicit path Path option: sr35142

[Harold Ritter]

Hi Yvan,

Can you post the output of the following commands:

show segment-routing traffic-eng policy name sr35142 detail

and

show isis segment-routing connected-sid

Regards,

[Yvan.hua]

Hi Harold,

      please check:

R3#show segment-routing traffic-eng policy name sr35142 detail

Name: sr35142 (Color: 10 End-point: 6.6.6.6)
Status:
Admin: up, Operational: down for 27:12:06 (since 07-19 02:03:51.5 90)
Candidate-paths:
Preference 10:
Explicit: segment-list sr35142 (inactive)
Inactive Reason: source address is not specified
Weight: 10, Metric Type: TE
Attributes:
Binding SID: 29
Allocation mode: dynamic
State: Programmed
Forwarding-ID: 65536 (0x14)
Stats:
Packets: 0 Bytes: 0

Event history:
Timestamp Client Event type Context: Value
--------- ------ ---------- -------: -----
07-19 02:03:51.590 CLI AGENT Policy create d Name: sr35142
07-19 02:03:51.590 CLI AGENT Set colour Colour: 10
07-19 02:03:51.590 CLI AGENT Set end point End-point: 6.6.6.6
07-19 02:03:51.591 CLI AGENT Set explicit path Path option: sr35142
07-19 02:16:31.251 CLI AGENT Set explicit path Path option: sr35142

R3# show isis seg con
R3# show isis seg connected-sid
Tag null:

IS-IS Level-2 connected prefix-sids:
Host Prefix SID Index Range Flags
R3 * 3.3.3.3/32 300 1
R5 5.5.5.5/32 500 1
R2 2.2.2.2/32 200 1
R6 6.6.6.6/32 600 1
R4 4.4.4.4/32 400 1
R1 1.1.1.1/32 100 1

[Harold Ritter · Accepted solution]

Hi @Yvan.hua ,

Make sure you enable "mpls traffic-end tunnels" globally and that interface level for all participating routers.

Also, you need to add the following statements to isis:

router isis

mpls traffic-eng router-id Loopback0
mpls traffic-eng level-2

Regards,

[Yvan.hua]

Hi Harold,

I have enabled "MPLS Traffic-ENG Tunnels" on all routers and MPLS interfaces, and then add your commands under the ISIS process. It really solved my problem, thank you very much.
But there is a new error, can I find the IOS-XE configuration manual?
Also want to ask questions, is the difference between these two configuration segment-list?
1. ip explicit-path name xxx
2. segment-routing traffic-eng
segment-list name xxx

Error Details:
R3#show segment-routing traffic-eng policy all detail

Name: sr35142 (Color: 10 End-point: 6.6.6.6)
Status:
Admin: up, Operational: down for 47:29:01 (since 07-19 02:03:51.590)
Candidate-paths:
Preference 10:
Explicit: segment-list sr35142 (inactive)
Inactive Reason: path cannot be resolved
Weight: 10, Metric Type: TE
Attributes:
Binding SID: 30
Allocation mode: dynamic
State: Programmed
Forwarding-ID: 65536 (0x12)
Stats:
Packets: 0 Bytes: 0

Event history:
Timestamp Client Event type Context: Value
--------- ------ ---------- -------: -----
07-19 02:03:51.590 CLI AGENT Policy created Name: sr35142
07-19 02:03:51.590 CLI AGENT Set colour Colour: 10
07-19 02:03:51.590 CLI AGENT Set end point End-point: 6.6.6.6
07-19 02:03:51.591 CLI AGENT Set explicit path Path option: sr35142
07-19 02:16:31.251 CLI AGENT Set explicit path Path option: sr35142
07-20 09:24:55.187 CLI AGENT Policy ADMIN DOWN shutdown: sr35142
07-20 09:24:59.594 CLI AGENT Policy ADMIN DOWN shutdown: sr35142
07-20 09:25:07.790 CLI AGENT Policy state DOWN no shutdown: sr35142
07-21 01:26:10.439 CLI AGENT Policy ADMIN DOWN shutdown: sr35142
07-21 01:26:12.869 CLI AGENT Policy state DOWN no shutdown: sr35142

R3#
R3#show run | se sr35142
segment-list name sr35142
index 10 mpls label 16400
policy sr35142
color 10 end-point 6.6.6.6
candidate-paths
preference 10
explicit segment-list sr35142 weight 10
constraints
segments
dataplane mpls

regards

Yvan

[Harold Ritter]

Hi Yvan,

Try changing the label in the segment-list to fix the "path cannot be resolved" issue.

segment-list name sr35142
index 10 mpls label 16600 <++++++ Label for 6.6.6.6

Or if you want to force traffic through router 4.4.4.4

segment-list name sr35142
index 10 mpls label 16400 

index 20 mpls label 16600 

> Also want to ask questions, is the difference between these two configuration segment-list?
> 1. ip explicit-path name xxx
> 2. segment-routing traffic-eng
> segment-list name xxx

1. is for the legacy SRTE tunnel based CLI. 2. is for the new policy based SRTE CLI. 

Regards,

[Yvan.hua]

Hi Harold，

      I tried to do some policy, the problem has been solved, thank you very much for your help.
      I met a question when I did experiment yesterday. You look at whether it is normal.

----------------------------------------------------------------------------------

 segment-list name sr35142

  index 10 mpls label 16500

  index 20 mpls label 27 //adj-sid,R5-R1

  index 30 mpls label 16600

 !

 segment-list name sr3542

  index 10 mpls label 16500

  index 20 mpls label 17 //adj-sid,R5-R4

  index 30 mpls label 16200

  index 40 mpls label 16600

 !

 policy po1

  color 10 end-point 6.6.6.6

  candidate-paths

   preference 20

    explicit segment-list sr3542

    !

   preference 10

    explicit segment-list sr35142

--------------------------------

Under normal circumstances, SR3542 is acvie, but when the adj-sid 17 is invalid(I shutdown R5 g0/0/1), SR3542 is still Active, show information is as follows, is this normal?

Name: po1 (Color: 10 End-point: 6.6.6.6)

  Status:

    Admin: up, Operational: up for 00:09:36 (since 07-21 10:55:09.709)

  Candidate-paths:

    Preference 20:

      Explicit: segment-list sr3542 (active)

        Weight: 0, Metric Type: TE

          16500 [Prefix-SID, 5.5.5.5]

          17

          16200

          16600

    Preference 10:

      Explicit: segment-list sr35142 (inactive)

        Weight: 0, Metric Type: TE

          16500 [Prefix-SID, 5.5.5.5]

          27 [Adjacency-SID, 15.1.1.5 - 15.1.1.1]

          16600 [Prefix-SID, 6.6.6.6]

  Attributes:

    Binding SID: 30

      Allocation mode: dynamic

      State: Programmed

---------------------------------------------

After that, I did another experiment. If the first hop label fails, the high priority path will become inactive, the low priority path is become active, and the Show information is as follows.
So only when the label of the first jump is invalid, the path will change, is this?

Name: po1 (Color: 10 End-point: 6.6.6.6)

  Status:

    Admin: up, Operational: up for 00:27:14 (since 07-21 10:55:09.709)

  Candidate-paths:

    Preference 20:

      Explicit: segment-list sr326 (inactive) // I shutdown a interface，it become inactive

        Inactive Reason: unresolved first hop

        Weight: 0, Metric Type: TE

    Preference 10:

      Explicit: segment-list sr3542 (active) //become active

        Weight: 0, Metric Type: TE

          16500 [Prefix-SID, 5.5.5.5]

          17 [Adjacency-SID, 45.1.1.5 - 45.1.1.4]

          16200 [Prefix-SID, 2.2.2.2]

          16600 [Prefix-SID, 6.6.6.6]

  Attributes:

    Binding SID: 30

      Allocation mode: dynamic

      State: Programmed

Regards

Yvan.hua

[Harold Ritter]

Hi Yvan,

I am glad it works for you. As far as the behavior you are seeing with the sid-list, it is as expected. If you specify labels as part of the sid-list, only the first hop is validated. If you want all the hops to be validated, you need to use IP addresses instead.

This behavior is described in slides 22 and 23 of the following presentation.

https://www.segment-routing.net/images/SRTE_TOI_dev_v20a_EXTERNAL.pdf

Regards,

[Wippe]

l saw the network mogul!!!!