• A router’s role is divided into three functional planes. • The management plane handles local administration and monitoring tasks, such as maintaining counters and system state. • The control plane communicates with neighbouring devices and computes routing information for the network. • The forwarding plane deals with live traffic: When a packet arrives, its header is rewritten as needed, and the packet is forwarded to the next hop based on the Forwarding Information Base (FIB). • This article focuses on the architecture of the forwarding plane. • RIB, FIB, and forwarding architectures Routers maintain two primary databases: The Routing Information Base (RIB), built using routing protocols like OSPF, IS-IS, and BGP, and the Forwarding Information Base (FIB), which is derived from the RIB and used for packet forwarding.
Article Summaries:
- The article explains how modern routers split their functions into management, control, and forwarding planes, with a focus on the forwarding plane’s architecture. It contrasts centralized forwarding-where a single FIB resides on the supervisor-with distributed forwarding, where the FIB is replicated to line cards that forward packets locally. The Broadcom DNX/Jericho series is highlighted as a cell‑based distributed design, detailing its ingress/egress pipelines and the Rammon fabric chip that moves cells between forwarding chips. It also notes traffic‑scheduling mechanisms on line cards and examples of distributed control planes such as OpenFlow, InfiniBand Subnet Manager, and IP‑Clos Ethernet routing.
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