[j-nsp] Duplicate IP addresses on interfaces

[Richard A Steenbergen]

Once upon a time, Juniper did a sensible thing and didn't let you 
configure the same IP address on two different interfaces on the same 
router. Then at some point in the past (the earliest I've noticed it was 
8.2, but it could have been earlier), somehow the error check for this 
condition got changed from a hard error (which prevented the config from 
committing) to a warning (which still allows the commit to continue).

I can't find a single legitimate reason for this behavior to exist. It
doesn't let you use both interfaces simultaniously, it doesn't let you
pre-stage a circuit move so you can move the link from one port to
another, and as best as I can tell it either breaks routing on both
interfaces or at best arbitrarily allows one interface to work while
breaking all the rest. This is very clearly a problem, which allows a
simple typo to break routing for an existing interfaces, and yet in the
past year+ that I've been complaining about this Juniper has claimed
that it is functioning as designed and that it can't be PR'd.

At this point, I'm calling bullshit. Unless someone can come up with a 
legitimate reason for this behavior to exist, which seems highly 
unlikely, I'm pretty damn sure that this is a bug which needs fixing 
and I'd like the other users of this list to tell Juniper as much.

[edit interfaces]
ras at lab-mx480# show 
xe-0/1/0 {
    unit 0 {
        family inet {
            address 10.70.70.1/30;
        }
    }
}
xe-0/3/0 {
    unit 0 {
        family inet {
            address 10.70.70.1/30;
        }
    }
}

root at lab-mx480# commit check 
[edit interfaces xe-0/3/0 unit 0 family inet]
  'address 10.70.70.1/30'
    warning: identical local address is found on different interfaces
configuration check succeeds

-- 
Richard A Steenbergen <ras at e-gerbil.net>       http://www.e-gerbil.net/ras
GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)