Hi list, I have a bunch of three routers running in a project, let's call them A, B and C. They connect to multiple AS upstream and internally via OSPF and RIPng. While B is based on an (ancient) Ubuntu 12.04.5 and (also ancient) Quagga (0.99.20.1), A and C run very recent CentOS 7 and FRR 6.0.2. B performs perfectly, while A and C put massive pressure on some Cisco switches they're connected to (OSPF and RIPng): They're sending about 2k ARP requests per second each. Looking at the ARP table (``ip nei show'') of A and C, I see about 20k entries, almost all of them in nud "FAIL" (unreachable). Most of them are IPs within the customer's AS (this is VLAN310 in the graphs attached), but some are random public IPv4 addresses. I did compare all sysctl settings to no avail, they're all set in a sane and safe manner. Every daemon not needed or adding not necessary complexity (like NetworkManager) is disabled and not running on A and C. ARP flux can be ruled out, too. Any idea what is going on here? Best Bernd
