Cisco Cisco Network Capacity Expansion 数据表
Data Sheet
© 2008 Cisco Systems, Inc. All rights reserved. This document is Cisco Public Information.
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Cisco NCE is a symmetric solution that requires a pair of peer devices between end nodes. Each
NCE module is capable of simultaneously increasing throughput for multiple peers, allowing hub-
to-spoke and meshed deployments. For central office (headend) aggregation, NCE is available in
the Network Module Extended (NME) form factor that is supported on the Cisco 3825 and 3845
ISRs. Table 1 summarizes the various supported NCE configurations.
Table 1.
Supported Cisco NCE Configurations
SKU
Use Case
WAN Capacity
ISR Platforms
Number of
Remote Peers
Remote Peers
Users
AIM-TPO-1
Bandwidth/link optimization
2 Mbps (T1/E1)
Cisco 1841, 2801, 2811,
2821, and 2851 ISRs
2821, and 2851 ISRs
5
<25
AIM-TPO-2
Bandwidth/link optimization
4 Mbps (2xT1/E1)
Cisco 1841, 2801, 2811,
2821, 2851, 3825, and 3845
ISRs
2821, 2851, 3825, and 3845
ISRs
10
<50
NME-TPO
Headend aggregation
45 Mbps
Cisco 3825 and 3845 ISRs
50
–
Compression Increases Effective Bandwidth
Cisco NCE implements several compression techniques to overcome bandwidth limitations:
payload compression, redundant header elimination, and efficient packet packing. For payload
compression, NCE uses hardware implementation of the open standard Deflate algorithm with
dynamic Huffman coding that preserves compression dictionaries across multiple packets.
Payload compression yields 3:1 to 10:1 compression on standard benchmarks (Standard
Canterbury Corpus). For redundant header elimination, NCE multiplexes several TCP sessions
into a single SCTP stream, substituting TCP headers with the much smaller SCTP “chunk”
identifiers. Finally, for efficient packet packing, NCE tightly bundles multiple compressed packets
into the path maximum transmission unit (MTU), helping to ensure that no partially filled data link
layer frame is sent across the WAN.
Transport Optimization Improves Bandwidth Utilization
Cisco NCE implements several optimization techniques to mitigate the effects of latency, packet
loss and congestion: TCP protocol optimization and packet flow control. For TCP optimization,
NCE transparently splices SCTP streams into TCP sessions that connect end nodes. The open
standard SCTP inherits all the benefits of TCP, adds reliability features, and was designed ground
up to overcome inefficiencies inherent in TCP. The use of SCTP to encapsulate traffic leads to a
significant improvement in bandwidth utilization. For packet flow control, NCE paces WAN-bound
traffic to match the prevailing WAN conditions, helping to ensure that packets are not dropped
because of congestion.