CHAPTER 8
Switch Fabric Components and
Descriptions
•
M7i Compact Forwarding Engine Board (CFEB) and Enhanced Compact Forwarding
Engine Board (CFEB-E) Description on page 63
•
M7i CFEB and CFEB-E LEDs on page 69
M7i Compact Forwarding Engine Board (CFEB) and Enhanced Compact Forwarding
Engine Board (CFEB-E) Description
The M7i Multiservice Edge Router houses either a Compact Forwarding Engine Board
(CFEB) or an Enhanced Compact Forwarding Engine Board (CFEB-E), which is located
on the rear of the router above the power supplies, as shown in Figure 6 on page 12. It
provides route lookup, filtering, and switching on incoming data packets, then directs
outbound packets to the appropriate interface for transmission to the network. It can
process 16 million packets per second (Mpps). The CFEB or CFEB-E communicates with
the Routing Engine using a dedicated 100-Mbps link that transfers routing table data
from the Routing Engine to the forwarding table. The link is also used to transfer routing
link-state updates and other packets destined for the router from the CFEB or CFEB-E
to the Routing Engine.
The CFEB or CFEB-E provides the following functions:
•
Route lookups—Performs route lookups using the forwarding table stored in the
synchronous SRAM (SSRAM) on CFEBs or stored in the RLDRAM on CFEB-Es.
•
Management of shared memory —Uniformly allocates incoming data packets
throughout the router's shared memory.
•
Transfer of outgoing data packets—Passes data packets to the destination FIC or PIC
when the data is ready to be transmitted.
•
Transfer of exception and control packets—Passes exception packets to the
microprocessor on the CFEB or CFEB-E, which processes almost all of them. The
remainder are sent to the Routing Engine for further processing. Any errors originating
in the Packet Forwarding Engine and detected by the CFEB or CFEB-E are sent to the
Routing Engine using system log messages.
•
Built-in tunnel interface—Encapsulates arbitrary packets inside a transport protocol,
providing a private, secure path through an otherwise public network.
63Copyright © 2019, Juniper Networks, Inc.
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