Specifications

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3.4 Virtual Private Networks
3.4.1 Layer 2 Virtual Private Networks
Today, the Juniper Networks proposal for Virtual Private Networks is based on a
Juniper feature set called MPLS Circuit Cross Connect.
The Circuit Cross-Connect (CCC) feature enables the transparent connection of
two layer 2 circuits at different edges of the network. Because no layer three
parsing or lookup is done, CCC supports the transmission of any layer 3
protocols in the packet payload. CCC consists of a static mapping of incoming to
outgoing logical ports, VCs or DLCIs.
Because the routing protocol on each customer's network is invisible to the
routers in the service provider's network, the various customers' networks are
inherently unable to share traffic and can support overlapping IP addresses
between VPNs. CCC eliminates the potential coupling of routing instability
between customer networks or between a customer network and the backbone
network, as seen in a multiple routing table implementation.
Supported encapsulations include :
§ PPP,
§ Cisco HDLC,
§ Frame Relay,
§ ATM,
§ Ethernet 802.1q VLANs.
This mechanism allows the creation of "tunnels" through a MPLS backbone
network cloud, between the CPE routers as per the diagrams below :
CPE
CPE
DLCI
600
DLCI
610
LSP 1
LSP 2
DLCI
608
DLCI
605
PE
PE
PE
CPE
Large Provider IP/MPLS Network
20.0.0.0
10.0.0.0
Source
Routing Table
In Out
DLCI 60010/8
DLCI 61020/8
Routing Table
In Out
DLCI 60010/8
DLCI 61020/8
Table
In Out
DLCI 608LSP2
Table
In Out
DLCI 608LSP2
Table
In Out
DLCI 605LSP1
Table
In Out
DLCI 605LSP1
“Good Service SP”
(USA Region)
“Good Service SP”
(Europe Region)
“Good Service SP”
(Asia Region)
In Out
LSP 1DLCI 600
LSP 2DLCI 610
Table
In Out
LSP 1DLCI 600
LSP 2DLCI 610
Table
Example network with CCC for Frame Relay
CPE
CPE
VLAN 2
VLAN 3
LSP 1
LSP 2
VLAN 3
VLAN 2
PE
PE
PE
CPE
Large Provider IP/MPLS Network
20.0.0.0
10.0.0.0
Source
Routing Table
In Out
VLAN 210/8
VLAN 320/8
Routing Table
In Out
VLAN 210/8
VLAN 320/8
Table
In Out
VLAN 3LSP2
Table
In Out
VLAN 3LSP2
Table
In Out
VLAN 2LSP1
Table
In Out
VLAN 2LSP1
“Good Service SP”
(USA Region)
“Good Service SP”
(Europe Region)
“Good Service SP”
(Asia Region)
In Out
LSP 1VLAN 2
LSP 2VLAN 3
Table
In Out
LSP 1VLAN 2
LSP 2VLAN 3
Table
Example network with CCC for Ethernet 802.1q VLANs