user manual

Configuring Headend Broadband Access Router Features
QoS Features
MC-527
Cisco IOS Multiservice Applications Configuration Guide
• Source and destination TCP/UDP port numbers
• IP protocol type
• Type of Service (ToS) field
• TCP flags
• Source and destination autonomous system numbers
• Source and destination subnet masks
Tag Switching
Tag switching is a Cisco-developed technology that implements a next-generation architecture for the
Internet backbone and large intranets. Tags placed on the fronts of packets contain forwarding
information used for making switching decisions and applying network services.
Tag switching has become the foundation for flexible Layer 3 virtual private networks (VPNs), QoS
handling, and traffic engineering. It also forms the basis for the emerging Internet Engineering Task
Force (IETF) standard for Multiprotocol Label Switching (MPLS).
A tag switching infrastructure combines with advanced routing protocol capabilities to define IP VPNs
by selectively advertising IP reachability information to just those subscribers within the same VPN or
extranet, thus keeping different VPN traffic logically separate. The subscribers are then all connected
via tag switch paths (TSPs).
Forwarding is based entirely upon the assigned tag values (rather than IP destination prefixes),
eliminating the requirement for uniqueness in the IP addresses that are used. This feature means
subscribers to different VPNs need not concern themselves with the problems that would otherwise
occur when connecting networks with different subnetworks into an integrated network.
Netflow Switching
NetFlow switching is a high-performance, network-layer switching path that provides network
administrators with access to “call detail recording” information from their data networks; this
information includes details such as user, protocol, port, ToS information, and the duration of the
communication. This data can be used for a variety of purposes, including billing, enterprise accounting,
network planning and performance analysis, QoS bandwidth management, security policies, and data
warehousing/mining for marketing purposes.
The collected NetFlow data is sent out via UDP packets to a workstation running the Netflow
Flowcollector server, which can collect data from multiple routers for later analysis by a user running
the Netflow Flowanalyzer application. Through the NetFlow Data Export feature, traffic information can
also be passed to external applications that perform functions such as billing or network performance
analysis.
NetFlow also provides a highly efficient mechanism that can process security access lists without
incurring the same performance penalty as other available switching methods. In conventional switching
at the network layer, each incoming packet is handled on an individual basis with a series of functions
to perform access list checks, capture accounting data, and switch the packet. In contrast, after NetFlow
switching identifies a flow and processes the access list for the first packet of the flow, all subsequent
packets are handled on a “connection-oriented” basis as part of the flow. This process avoids further
access list checks on the flow, and packet switching and statistics capture are performed in tandem.