Your company uses multi-vendor routing platforms (Cisco and Juniper) and has multiple sites connected via MPLS from a service provider.
Each remote site has a GRE tunnel with the Headquarter (HQ) and a BGP session over this tunnel, in order to learn prefixes that you don't want to be exchanged with your MPLS provider.
After attending a security training, your Security Team raised concerns about ICMP-based attacks and decided to
Some time after the Security Team implemented the above changes, you notice that the BGP session with Site-2 (Juniper-based CE) started to flap impacting the connectivity to this site.
After getting some more info, it seems that all Juniper-based CE sites are affected (BGP sessions go UP, they try to exchange prefixes but then NOTIFICATION is received and BGP goes down), while the BGP sessions to the Cisco-based CE sites are ok.
What is the problem and how to solve it?
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