[c-nsp] IOS-XR accepted duplicate subnet configurations for interface

[Rimestad, Steinar]

Hi.

As long as the l2 encapsulation is different the syntax is allowed even without vrf and as primary addresses.

You get a warning in the syslog and one of the addresses with the duplicate config is forced down.

Sep 27 09:13:09.372 : ipv4_arm[292]: %IP-IP_ARM-3-CFLCT_FORCED_DOWN : The IPv4 address 10.11.12.1/31 on Bundle-Ether100.2177 conflicts with other IPv4 addresses and has been forced down

You can check for any conflicts using "show arm conflicts".

/Steinar


On 27/09/2018, 00:21, "cisco-nsp on behalf of Martin Mehaffy" <cisco-nsp-bounces at puck.nether.net on behalf of martin.mehaffy at sparkventures.co.nz> wrote:

    I'd expect the commit to fail in that scenario. I'd log a TAC case and see what Cisco says.
    
    
    On 27/09/18, 10:15, "Randy" <randy_94108 at yahoo.com> wrote:
    
         From: Christoffer Hansen <cdh at nianet.dk>
         To: "cisco-nsp at puck.nether.net" <cisco-nsp at puck.nether.net>
         Sent: Wednesday, September 26, 2018 2:48 PM
         Subject: [c-nsp] IOS-XR accepted duplicate subnet configurations for interface
    
    
    
        Dear c-nsp fellows,
    
        I am not sure if any one of you would have an answer the the below
        example...
    
        I have recently run into a case with an ASR9k router running IOS-XR
        v5.3.4. Were I by accident put an identical secondary subnet on a 2nd
        interface located inside the same VRF as the first one. It is even a 2nd
        sub-interface to another sub-interface on the same main interface.
    
        Case-in-point: The router accepted the configuration commit without
        complaints and of course traffic then stops flowing.
    
        Normally I would not expect this to be possible to do. And would expect
        the router to output a warning telling me I am trying to commit an IPv4
        address|subnet already configured on another interface in the same VRF.
    
    
        Q: Would you expect
        (1) a warning in my scenario or
        (2) the router just accepting the staged configuration change upon commit?
    
    
        ```iosxr
        !!! 1st-subinterface
        !
        interface GigabitEthernet666/0/0/2.1478 !!nvSatellite interface
         vrf ROUTING-INSTANCE-INTERNET
         ipv4 mtu 1500
         ipv4 address 198.51.100.1 255.255.255.252
         ipv4 address 203.0.113.1 255.255.255.252 secondary
         ipv4 verify unicast source reachable-via any allow-default
         encapsulation dot1q 1478
        !
    
        !!! 2nd sub-interface
        !
        interface GigabitEthernet666/0/0/2.665 !!nvSatellite interface
         vrf ROUTING-INSTANCE-INTERNET
         ipv4 mtu 1500
         ipv4 address 192.0.2.1 255.255.255.252
         ipv4 address 203.0.113.1 255.255.255.252 secondary !!committed line
         ipv4 verify unicast source reachable-via any allow-default
         encapsulation dot1q 665
        !
        ```
    
        -Christoffer
    
        ---------------------------------------------------------------------------------------------------------------------------------------------------------------------Hi,It is a case of "missing a few check&balances. Happens! I have seen worse!A call to the TAC will help by the way of a bug-report/fix../Randy
    
    
    
    
    
    
    
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