HP Intelligent Management Center Licenses - Manual (Page 32)

1. Classified by networking model
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Virtual Private Dialup Network (VPDN): Point to point VPN
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Leased line VPN (VPRN, VPLS, VLL)
2. Classified by service application
•
Access VPN: Allows users and small offices to establish private network connections with
the intranet and extranet of their enterprise over a public network.
•
Intranet VPN: Interconnects points distributed inside an enterprise.
•
Extranet VPN: Extends an enterprise network to cooperators by using VPN.
3. Classified by operation mode
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CPE-based VPN (Customer Premises Equipment based VPN): IPsec VPN, GRE VPN, and
VPDN.
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Network-based VPN: Includes VLL, VPRN, VPLS and L3VPN, conducted by ISP, and all
functions are implemented at network device side.
4. Classified by working layer
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L2VPN
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L3VPN
Basic Concepts of MPLS
Multiprotocol Label Switching (MPLS), originating in IPv4, was initially proposed to improve
forwarding speed. Its core technology can be extended to multiple network protocols, such as IPv6,
Internet Packet Exchange (IPX), and Connectionless Network Protocol (CLNP). That is what the term
multiprotocol means.
MPLS integrates both Layer 2 fast switching and Layer 3 routing, satisfying the networking
requirements of various new applications. The following are the basic concepts of MPLS:
•
FEC
As a forwarding technology based on classification, MPLS groups packets to be forwarded
in the same manner into a class called a forwarding equivalence class (FEC). That is, packets
of the same FEC are handled in the same way. The classification of FECs is very flexible. It
can be based on any combination of source address, destination address, source port,
destination port, protocol type and VPN. For example, in traditional IP forwarding using
longest match, all packets to the same destination belong to the same FEC.
•
Label
A label is a short fixed length identifier for identifying a FEC. A FEC may correspond to multiple
labels in scenarios where, for example, load balancing is required, while a label can only
represent a single FEC. A short label can enhance processing capability. It does not contain
any topology information and is local significant.
•
LSP
Label switching path (LSP) means the path along which a FEC travels through an MPLS network.
MPLS Forwarding
The element of an MPLS network is label switching router (LSR). LSRs in the same routing or
administrative domain form an MPLS domain. In an MPLS domain, LSRs residing at the domain
border to connect with other networks are label edge routers (LERs), while those within the MPLS
domain are core LSRs. All core LSRs, which can be routers running MPLS or ATM-LSRs upgraded
from ATM switches, use MPLS to communicate, while LERs interact with devices outside the domain
that use traditional IP technologies. Each packet entering an MPLS network is labeled on the ingress
32 MPLS Manager