- Introduction
- What is the Queue Link / Queue Link Error ?
- Troubleshooting - Queue Link Error
- Cause=basic_cancel
- Cause=Timeout
- Cause=Econnrefused
- Cause={tls_alert;"handshake failure"}
- Cause={tls_alert;"unknown Ca"}
- Generate Signing Requests (CSR)
- Other Causes
- Effect of Queue Link Error !!!
- ISE Messaging Settings
- Light Data Distribution (LDD)
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Introduction
This document briefly introduces the meaning of Queue Link Error, how to deal with it, and its impact on ISE Deployment.
What is the Queue Link / Queue Link Error ?
Since ISE 2.6 the ISE RabbitMQ Container was renamed to ISE Messaging Service (a Message Broker Container that runs on a Docker). ISE Messaging Service is started on each ISE Node and used for exchanging information between Nodes (via TLS using a Certificate issued by ISE's Internal CA). Queue Link is the connection between these Nodes, and Queue Link Error means that something went wrong !!!
This Alarm is expected in case you are performing any Deployment operations such as: registering a Node to Deployment, manually syncing a Node from PPAN, a Node being in out-of-sync state, a Node Application Service is getting restarted, changing the Domain Name or Hostname of your PAN/PSN, restoring a Backup on a New Deployment or Promoting the Old PPAN to New PPAN post upgrade.
You are able to check the ISE Messaging Service via ISE CLI using the following command:
ise/admin# show application status ise
ISE PROCESS NAME STATE PROCESS ID
-----------------------------------------------------
Database Listener running 15215
Database Server running 131 PROCESSES
Application Server running 27711
...
Docker Daemon running 16843
TC-NAC Service disabled
...
ISE Messaging Service running 43944
Segmentation Policy Service disabled
SSE Connector disabled
IMPORTANT: " ... the Process Down alarm is no longer triggered when ISE Messaging Service fails on a Node. When ISE Messaging Service fails on a Node, ALL the Syslogs and the Process Down alarm will be lost until the Messaging Service is brought back up on that Node... " (at Cisco ISE 3.1 Maintain and Monitor) !!!
Troubleshooting - Queue Link Error
At ISE > Home you may see the Queue Link Error record in the Alarms dashboard:
Click the Queue Link Error record to open a detail description of it:
The description of the Suggested Actions is:
"Please check and restore connectivity between the Nodes.
Ensure that the Nodes and the ISE Messaging Service are up and running.
Ensure that ISE Messaging Service ports are not blocked by Firewall.
Please note that these Alarms could occur between Nodes, when the Nodes are being registered to Deployment or manually-synced from PPAN or when the Nodes are in out-of-sync state or when the Nodes are getting restarted."
You can also check this info at Operations > Reports > Reports > Audit > Operations Audit > filtering by:
- Object Type = System-Management
- Requested = The federation link was down or Event = Unknown CA
Note: ISE Messaging Services uses port TCP/8671 !!! Please take a look at the following ISE CLI command:
ise/admin# show ports
...
Process : docker-proxy (43916)
tcp: :::8671
Note: TCP/8671 is used by ALL Nodes (PAN, MnT and PSN) for Inter-Node Communication. Please take a look at the following ISE CLI commands:
isePAN/admin# show logging application ise-messaging/rabbit-ise-connection.log
...
2022-11-22 18:47:39.224 [error] <0.7017.0>@rabbit_reader:log_hard_error:785 Error on AMQP connection <0.7017.0> (<PSN IP Addr>:40486 -> 169.254.x.y:5671 - Federation link (upstream: E-Mesh-FOR-<PAN Hostname>:8671-TO-<PSN Hostname>, policy: Policy-FullMesh), vhost: '/', user: 'rabbitmq', state: running), channel 0:
...
isePSN/admin# show logging application ise-messaging/rabbit-ise-connection.log
2022-11-22 18:47:39.201 [warning] <0.3335.1078>@rabbit_reader:log_connection_exception_with_severity:447 closing AMQP connection <0.3335.1078> (<PAN IP Addr>:50533 -> 169.254.x.y:5671 - Federation link (upstream: E-Endpoints-FOR-<PSN Hostname>:8671-TO-<PAN Hostname>, policy: Policy-Endpoints), vhost: '/', user: 'rabbitmq'):
...
Examples of Causes that you may see on the Queue Link Error message:
- Cause=basic_cancel
- Cause=Timeout
- Cause=Econnrefused
- Cause={tls_alert;"handshake failure"}
- Cause={tls_alert;"unknown Ca"}
Note: it's also possible to see the Queue Link Error message via ISE CLI with the following command:
ise/admin# show logging application ise-messaging/rabbit-ise-federation.log
...
2022-06-05 02:55:04.776 [warning] <0.446.0>@rabbit_federation_link_util:log:283 Federation exchange 'E-Mesh' in vhost '/' did not connect to exchange 'E-Mesh' in vhost '/' on amqps://<Node IP Addr>:8671
{error,{tls_alert,"unknown ca"}}
Cause=basic_cancel
The reason for this error showing up is usually when: changing hostname of ISE Nodes or there has been a Node Promotion (there are residual links from Old PAN to the rest of the Deployment which are sometimes not cleaned up on promotion)!!!
Please take a look at:
- CSCvs01949 ISE Messaging service triggers Queue Link error alarms with the reason basic_cancel.
- CSCvr64000 Hostname change causes ISE Messaging issues - MNT Failover and Queue Link Error-basic_cancel.
Cause=Timeout
This Alarm cause no functional impact, it is potentially caused by Network Congestion during the time of alarms between the Nodes Alarm is triggered for ... these can be ignored !!!
Please take a look at:
- CSCvv99093 ISE Nodes intermittently trigger Queue Link Alarms : Cause=Timeout.
- CSCwa82247 ISE Queue Link Error : Cause=Timeout due to 169.254.2.0/25 in ISE iptables.
- CSCwa43187 ISE Queue Link Error: Message=From Node1 To Node2; Cause=Timeout in NAT'ed deployment.
Also double check the TCP 8671 flow between the Nodes, via ISE CLI:
ise/admin# tech dumptcp 0 | inc 8671
tcpdump: listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes
10.10.10.1.34190 > 10.10.10.2.8671: Flags [S], cksum 0x9544 (correct), seq 113726506, win 29200, options [mss 1460,sackOK,TS val 2259048610 ecr 0,nop,wscale 7], length 0
--
10.10.10.2.8671 > 110.10.10.1.34190: Flags [S.], cksum 0x5f32 (incorrect -> 0xf139), seq 1497652336, ack 113726507, win 28960, options [mss 1460,sackOK,TS val 2258331801 ecr 2259048610,nop,wscale 7], length 0
--
Cause=Econnrefused
This Alarm is considered as cosmetic. It is potentially caused by a period of time when it is unable to connect to your Node and the connection is refused !!!
Please take a look at:
Cause={tls_alert;"handshake failure"}
There are several possible reasons for the error, but most often it is due to a problem with the Certificate Chain used by the ISE Messaging Service. Please take a look at Generate Signing Requests (CSR) bellow.
Cause={tls_alert;"unknown Ca"}
There are several possible reasons for the error:
1. when Dedicated MnT option is selected (at Administration > System > Deployment > select the MnT Node and check Dedicated MnT) ... take a look at:
2. when utilizing Third-Party signed certificate ... take a look at:
3. but most often it is due to a problem with the Certificate Chain used by the ISE Messaging Service. Please take a look at Generate Signing Requests (CSR) bellow.
Generate Signing Requests (CSR)
1st double check if the Certificate Authority is enabled, at Administration > System > Certificates > Certificate Authority > Internal CA Settings > if you see Disable Certificate Authority, then it's enabled !!!
2nd if it's just a problem with the ISE Messaging Service of a particular Node(s), at Administration> System> Certificates> Certificate Management> Certificate Signing Requests > click Generate Certificate Signing Requests (CSR):
Select ISE Messaging Service in Usage, select the Node(s) you want to reissue and generate by clicking Generate ISE Messaging Service Certificate:
The following message appear:
IMPORTANT: during the generation of the ISE Messaging Service there is NO reboot or Deployment break, only the initialization of the ISE Messaging Service !!!
3rd if it's not just a problem with the ISE Messaging Service of a particular Node(s), you may need to replace the entire Chain of Internal CAs, at Administration> System> Certificates> Certificate Management> Certificate Signing Requests > click Generate Certificate Signing Requests (CSR) > select ISE Root CA in Usage and click Replace ISE Root CA Certification Chain:
The following message appear:
IMPORTANT 1: when you replace the Cisco ISE Root CA chain, the Cisco ISE Messaging Service Certificate is also replaced. This is followed by the restart of the Cisco ISE Messaging Service with a downtime of about 2 minutes. During the replacement of the ISE Root CA there is NO reboot or Deployment break !!!
IMPORTANT 2: to avoid losing the Syslogs during the downtime, disable for a short period of time the Cisco ISE Messaging Services (at Administration > System > Logging > Log Settings > uncheck the Use "ISE Messaging Service" for UDP Syslogs delivery to MnT
IMPORTANT 3: if you notice a Slow Replication on Secondary Nodes post re-generating the Root CA, then re-registering the Secondary Node will fix the issue, please take a look at:
4th at Administration > System > Certificates > Certificate Authority > Certificate Authority Certificates, Delete & Revoke old Certificates.
IMPORTANT 1: when you re-generate the Internal CA Root Chain, ISE does not delete the Old One automatically. As long as ISE retains the Old Root Chain, it will Trust Certificates presented by the Endpoints with Identity Certificates signed by that Chain (if that is the case) !!!
IMPORTANT 2: delete Old Internal Certificates is an important step to prevent some bugs with 200+ Internal Certificates on PPAN that causes Slow UI, Slow Replication and High CPU/Load, please take a look at:
Other Causes
Other causes of Queue Link Error:
Please take a look at:
- CSCwa73860 After Upgrade, the files in the rabbitmq cert directory have incorrect permissions.
- CSCvz37241 Move Queue Link Error from WARN to Critical and Restart if Timeout
- CSCvr40715 Enhance CA to ensure certificate chain is intact post an upgrade or DB restore
- CSCvp45528 Queue Link Error alarm generated after signing of ISE CA certificate by external Root CA
Effect of Queue Link Error !!!
The Queue Link Error may not be harmful depending on the usage situation. Let's take a look of some examples the ISE Messaging Service is used.
ISE Messaging Settings
If there is a problem with Queue Link and there is a problem with log transfer to MnT between PSN and MnT:
- Live Logs are not displayed
- Report is not displayed
- Dashboard System Summary is not displayed
In addition to the above measures, this event may be recovered by unchecking the Use "ISE Messaging Service" for UDP Syslogs delivery to MnT (enabled by default since ISE 2.6 P2) and switching to log transfer that does not go through the Messaging Service at Administration > System > Logging > Log Settings > ISE Messaging Settings:
Please take a look at:
Light Data Distribution (LDD)
