IXP425 INTEL [Intel Corporation], IXP425 Datasheet - Page 2

• Manufacturer Part Number: IXP425
• Description: Optimized for Broadband Applications
• Manufacturer: INTEL [Intel Corporation]

Distributed Processing Architecture
The three NPEs are designed to offload many computa-
tionally intensive data plane operations from the Intel
XScale core. These tasks include: IP header inspection
and modification; packet filtering; packet error checking;
check sum computation; flag insertion and removal; PDU
segmentation and assembly; and encryption. The NPE
architecture includes an ALU, self-contained internal data
memory, an extensive list of I/O interfaces, together with
hardware acceleration engines (also known as NPE
coprocessors). It is the NPE coprocessor associated
with an NPE that targets a set of networking applications.
Each NPE coprocessor is designed to accelerate a
specific networking task that would otherwise take many
MIPs to complete by a stand-alone RISC processor.
Layer 3 packets that are passed through them. For example,
the WAN/Voice NPE has one UTOPIA 2 interface and two
high-speed serial interfaces so its internal processing is
targeting the handling of AAL (1/2/5) SARing, TDM framing,
and HDLC processing. An MII/RMII interface is attached
to both the Ethernet NPE A and the Ethernet NPE B
respectively. The Ethernet NPE A also has two internal
coprocessors to accelerate VPN related tasks such as
3DES and Hashing at speeds up to full-rate ADSL. The
Ethernet NPE B is capable of handling 100Mb/s, full-duplex
Ethernet packet filtering. The extensive hardware capabilities
of these NPEs are all under the management of a set of
NPE microcode drivers that are released as a software
Each NPE can take care of Layer 2 and, in some cases,
( continued )
library together with the Intel IXP425 network processors.
Customer applications configure and interact with the
NPEs through a high-performance API layer running on
the Intel XScale core.
Wire-Speed Performance
The Intel IXP425 network processors implement a fast
path design in the NPE software library to provide
optimized performance for broadband applications.
The fast path design passes non-inspection IP packets
directly from the ingress port NPE (usually WAN/Voice
NPE with the xDSL WAN port) to the egress port NPE
(usually Ethernet NPE A or B with the Ethernet LAN port)
without the involvement of the Intel XScale core. Since
the vast majority of IP packets move from the WAN to
the Ethernet LAN, isolating these data flows to the NPEs
within the Intel IXP425 network processor produces a
significant throughput improvement by eliminating the
need to route packets through a central processor. The
most demanding situation occurs when small (64 byte)
IP packets are sent at the speed that saturates the
physical layer (wire speed). For example, nearly 10,000
(64 byte) packets per second will be sent downstream
in an ADSL connection that runs at the maximum wire
speed (8 Mb/s downstream). The NPEs and fast path
design in the Intel IXP425 network processors are capable
of providing, at minimum packet sizes, wire-speed perfor-
mance up to 52 Mb/s on the WAN side and 100 Mb/s on
the Ethernet LAN.