Exploring the 'no-overwrite commit' Flag in Network Configuration

[BasharAziz]

Example Configuration: Let's consider a scenario where we need to create a loopback interface with an IP address and description on a router named 'router00' using the NSO (Network Service Orchestrator) management system.

1. Initial Configuration: We start by configuring the loopback interface with the desired IP address and description

   admin@ncs# config
   Entering configuration mode terminal
   admin@ncs(config)# services basic-service router00 int-name 123 loopback-ip 1.1.1.1 loopback-description main-int hostname ios-router
   admin@ncs(config-basic-service-router00)# commit dry-run outformat native
   native {
     device {
       name router00
       data hostname ios-router
       interface Loopback123
         ip redirects
         description "main-int"
         ip address 1.1.1.1 255.255.255.255
         no shutdown
       exit
     }
   }
   admin@ncs(config-basic-service-router00)# commit
   Commit complete.
   ​

2. Successful Deployment: The configuration is successfully applied to the router 'router00':

   router00# show running-config interface Loopback 123
   interface Loopback123
     description main-int
     no shutdown
     ip address 1.1.1.1 255.255.255.255
   exit
   router00#
   ​

   Addressing Out-of-Sync Issues: Now, let's explore different scenarios to demonstrate how the 'no-overwrite commit' flag handles out-of-sync issues effectively.Changing Loopback IP Address: We attempt to change the IP address of Loopback123 on the router:
3. Changing Loopback IP Address: We attempt to change the IP address of Loopback123 on the router:

   Entering configuration mode terminal
   router00(config)# interface Loopback123
   router00(config-if)# ip address 2.2.2.2 255.255.255.255
   router00(config-if)# commit
   Commit complete.
   ​

4. Out-of-Sync Detection: When we check the synchronization status using the NSO 'check-sync' command, we observe an 'out-of-sync' alarm:

   admin@ncs# devices device router00 check-sync
   result out-of-sync
   info got: 96b592b1356b7c339d3e3cda08a022f2 expected: e57de8d6d861d77af042ec30a54f26cc
   admin@ncs# *** ALARM out-of-sync: got: 96b592b1356b7c339d3e3cda08a022f2 expected: e57de8d6d861d77af042ec30a54f26cc
   admin@ncs#
   ​

5. Using 'no-overwrite' to Address Out-of-Sync: By making changes to the loopback description and using the 'no-overwrite' flag, we can prevent overwriting the out-of-sync configuration:

   admin@ncs(config-basic-service-router00)# loopback-description main-int-changed-by-nso
   admin@ncs(config-basic-service-router00)# commit no-overwrite
   Commit complete.
   admin@ncs(config-basic-service-router00)#
   ​
   

6. Successful Deployment: The configuration is successfully applied to the router 'router00':

   router00# show running-config interface Loopback 123
   interface Loopback123
   description main-int-changed-by-nso
   no shutdown
   ip address 2.2.2.2 255.255.255.255
   exit​

7. By manually making changes to the loopback description direct on the router:
   

   router00# config                                    
   Entering configuration mode terminal
   router00(config)# interface Loopback123             
   router00(config-if)# description main-int-changed-by-admin
   router00(config-if)# commit 
   Commit complete.
   router00(config-if)# 

8. By making changes to the loopback description with NSO and using the 'no-overwrite' flag, we can prevent overwriting the out-of-sync configuration:
   

   dmin@ncs(config-basic-service-router00)# loopback-description main-int-changed-by-nso
   admin@ncs(config-basic-service-router00)# loopback-description main-int-changed-by-nso-one-time-more
   admin@ncs(config-basic-service-router00)# commit no-overwrite                  
   Aborted: Network Element Driver: device router00: out of sync: for 'devices device router00 config interface Loopback 123 description'