Exception in callback: Neither the key nor the value can be null

[steven.crutchley]

Hi everyone,

I'm new to NSO and am working through the getting started guide and examples. Specifically the one found in the following folder on version 5.3:

~/nso-5.3/examples.ncs/service-provider/mpls-vpn/

I'm reaching the point whereby I check the dry-run config but I'm getting a strange exception insisting a value not be null:

admin@ncs(config)# show configuration
vpn l3vpn volvo
 route-distinguisher 100
 endpoint branch-office1
  ce-device    ce1
  ce-interface GigabitEthernet0/11
  ip-network   10.7.7.0/24
  bandwidth    6000000
 !
 endpoint branch-office2
  ce-device    ce4
  ce-interface GigabitEthernet0/18
  ip-network   10.8.8.0/24
  bandwidth    300000
 !
 endpoint main-office
  ce-device    ce0
  ce-interface GigabitEthernet0/11
  ip-network   10.10.1.0/24
  bandwidth    12000000
 !
!
admin@ncs(config)# commit dry-run outformat native
Aborted: Exception in callback: Neither the key nor the value can be null
admin@ncs(config)#

I'm not sure what is causing this. I'm guessing there is a policy necessitating an unseen value not be null but I'm unsure not sure how to find it. 

Thanks in advance. 

[steven.crutchley · Accepted solution]

Managed to solve my own problem. Turns out the AS number was required. 

admin@ncs(config)# vpn l3vpn volvo
admin@ncs(config-l3vpn-volvo)#
admin@ncs(config-l3vpn-volvo)# endpoint branch-office1
admin@ncs(config-endpoint-branch-office1)# as-number 65101
admin@ncs(config-endpoint-branch-office1)# exit
admin@ncs(config-l3vpn-volvo)# endpoint branch-office2
admin@ncs(config-endpoint-branch-office2)# as-number 65101
admin@ncs(config-endpoint-branch-office2)# exit
admin@ncs(config-l3vpn-volvo)# endpoint main-office
admin@ncs(config-endpoint-main-office)# as-number 65101
admin@ncs(config-endpoint-main-office)# top
admin@ncs(config)# show config
vpn l3vpn volvo
 route-distinguisher 100
 endpoint branch-office1
  ce-device    ce1
  ce-interface GigabitEthernet0/11
  ip-network   10.7.7.0/24
  bandwidth    6000000
  as-number    65101
 !
 endpoint branch-office2
  ce-device    ce4
  ce-interface GigabitEthernet0/18
  ip-network   10.8.8.0/24
  bandwidth    300000
  as-number    65101
 !
 endpoint main-office
  ce-device    ce0
  ce-interface GigabitEthernet0/11
  ip-network   10.10.1.0/24
  bandwidth    12000000
  as-number    65101
 !
!
admin@ncs(config)# commit dry-run outformat native
native {
    device {
        name ce0
        data policy-map volvo
              class class-default
               shape average 12000000
              !
             !
             interface GigabitEthernet0/11
              description volvo local network
              ip address 10.10.1.1 255.255.255.0
              
              <output omitted for brevity>

But out of interest, can anyone advise where I'd find the statement or policy necessitating an ASN? Looking at the native output it is clearly configuring BGP sessions which obviously require ASNs but I'm looking find where exact syntax and details were specified.

For example:

             router bgp 65101
              neighbor 192.168.1.2 remote-as 100 << where is ASN 100 set?
              neighbor 192.168.1.2 activate
              address-family ipv4 unicast
               neighbor 192.168.1.2 activate
               network 10.10.1.0 mask 255.255.255.0
               exit-address-family

Is this all templated into a yang model somewhere? I'll keep hunting but if anyone can help me track it down, that'd be awesome. I'm getting close to understanding the actual application of all this high level language, and nailing it down would be amazing helpful. 

[gmuloche]

Hello,

You can have a look at the templates in the l3vpn package in the example - for example for a ce device (l3vpn-ce.xml) the remote-as is hardcoded to be 100 for the PE neighbor.

        <router xmlns="urn:ios">
          <bgp>
            <as-no>{$CE_AS_NUM}</as-no>
            <neighbor>
              <id>{$LINK_PE_ADR}</id>
              <remote-as>100</remote-as>
              <activate/>
            </neighbor>
           <address-family>
            <ipv4>
              <af>unicast</af>
                <neighbor>
                  <id>{$LINK_PE_ADR}</id>
                    <activate/>
                </neighbor>
                <network>
                  <number>{$LOCAL_CE_NET}</number>
                  <mask>{$CE_MASK}</mask>
                </network>
            </ipv4>
           </address-family>
          </bgp>

[tcragg1]

Assuming this example is similar to the version in NSO 5.2, you should be able to find the YANG model for it at examples.ncs/service-provider/mpls-vpn/packages/l3vpn/src/yang/l3vpn.yang. However, at least in the NSO 5.2 version, the as-number leaf is not mandatory in the YANG model. If it were, I would also expect to see a different error (if you fail to provide data that the YANG model states is mandatory, I would expect to see a YANG validation failure message before it even attempts the service callback).

Instead, I think that error is being triggered by the java code that converts the data from the YANG model into variables to be inserted in the XML templates. You should be able to find the java source at examples.ncs/service-provider/mpls-vpn/packages/l3vpn/src/java/src/com/example/l3vpn/l3vpnRFS.java

While I don't really speak java, it looks to me like the code assumes that every CE will have an AS number, and will throw an exception if they don't.