[j-nsp] iBGP impacting eBGP

[Jad KAROUT]

I'm encountering a problematic issue on our juniper M7i.

We use this router to announce our prefix to the world via two  
carriers (ts and c&w). This router also establishes an iBGP link with  
another one of our routers.

So the BGP configuration goes something like this :

jad at JUNIPER-BGP> show configuration protocols bgp

traceoptions {
     file bgp.log size 1m files 5;
     flag normal;
     flag state;
}
log-updown;
group T-S {
     type external;
     authentication-key "$9$wrsoGUjkf5Q-dXtc.f5yreKx-oJDi.5lKjk"; ##  
SECRET-DATA
     export PREFIX_OUT;
     neighbor IP_TS {
         peer-as TS_AS;
     }
}

group XTS {
     type internal;
     local-address IP_J;
     neighbor IP_RB {
         export DONT_ADVERTISE;
     }
}

group CW {
     type external;
     authentication-key "$8*xtdpHKJHJKL-.hjkGUreKx-oJDi.ppWJoi"; ##  
SECRET-DATA
     export PREFIX_OUT;
     neighbor IP_CW {
         peer-as CW_AS;
     }
}


However due to changes in our architecture, the iBGP session is no  
longer needed and must be removed. I tried to do that by deleting the  
corresponding group in the BGP conf as it is now useless.
However, the second i commit that change, the M7i stops announcing  
our prefix to the two eBGP peers.

I don't understand how removing an iBGP session can impact eBGP  
sessions ?

Any idea anyone ?

Thanks.