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JunOS not identifying duplicate addresses on different interfaces of same device

‎01-10-2020 01:44 AM

Hi Fellow enthusiasts,

 

JunOS does not seem to identify duplicate IP addresses on the interface, commit check passes followed by commit itself. 

I have noticed that in Cisco and HP devices; the change does not go through and also it throws up an error. 

 

I just wanted to know why this logic is not present in JunOS, or is it that there is a possible reason why it is so?

 

I shall await your response...

 

labroot@jtac-mx480dc-r2038-re0# set interfaces ge-1/0/1 unit 0 family inet address 1.1.1.1/32

[edit]
labroot@jtac-mx480dc-r2038-re0# set interfaces ge-1/0/2 unit 0 family inet address 1.1.1.1/32

[edit]
labroot@jtac-mx480dc-r2038-re0# show | compare
[edit interfaces]
+ ge-1/0/1 {
+ unit 0 {
+ family inet {
+ address 1.1.1.1/32;
+ }
+ }
+ }
+ ge-1/0/2 {
+ unit 0 {
+ family inet {
+ address 1.1.1.1/32;
+ }
+ }
+ }

[edit]
labroot@jtac-mx480dc-r2038-re0# commit check
configuration check succeeds

[edit]
labroot@jtac-mx480dc-r2038-re0# commit
commit complete

 

3 REPLIES 3
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Junos

Re: JunOS not identifying duplicate addresses on different interfaces of same device

‎01-10-2020 02:09 AM

Hello,

 

At some point there was an attempt to add such check, but then it was reverted back to the original JUNOS day 1 behavior.

This is to support scenarios with 1:1 line side protection. In these scenarios customers configure identical addresses on different physical interfaces. One physical interface is active at a time (controlled by the transport equipment).

 

If someone needs to enforce additional checks, we have a commit script option.

 

Best regards,

Sergii

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Junos

Re: JunOS not identifying duplicate addresses on different interfaces of same device

‎01-14-2020 02:04 AM

I believe JUNOS SPACE has the option to check the duplicate IP address on the interface.

Also you get the error log if you have the duplicate interface ip.

Junos

Re: JunOS not identifying duplicate addresses on different interfaces of same device

‎02-12-2020 08:13 AM

Not that I like this behaviour, but it's documented: https://www.juniper.net/documentation/en_US/junos/topics/reference/general/interfaces-operational-be... 

And the log message is: DCD_PARSE_WARN_INCOMPATIBLE_CFG

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