A SIMPLE, REDUNDANT FORWARDING DESIGN
DIRTY VRFEdge router / InternetDirty VLAN
FILTER CLUSTERFILTER 01FILTER 02FILTER N
Traffic is analyzed in both directions CLEAN VRFCore switch / ServicesClean VLAN
One switch, or a redundant switch pair using MLAG or an equivalent design, connects the filter cluster to the clean and dirty networks.
01Three connections per filter
Two 100G ports run as an LACP pair for redundancy. Dirty traffic enters and exits on the dirty VLAN; clean traffic enters and exits on the clean VLAN. A third, out-of-band connection handles software and configuration updates, mitigation statistics, and network bootstrap after a catastrophic failure.
02Clear traffic domains
The switch or router routes between the two VLANs in separate Clean and Dirty VRFs. Where physical separation is preferred, use separate routers or switches instead—for example, an edge router on the dirty side and a core switch on the clean side.
03Failure preserves reachability
If a filter fails, traffic re-balances across the remaining filters. If every filter is unavailable, traffic shortcuts across the filter layer so services remain online. Protection should fail open, not turn an appliance fault into an outage.