PLANET XGS3-24042 - Manual (Page 703)

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Chapter 82 Public Network Access of MPLS
VPN
82.1 Public Network Access Introduction
Public network access of VPN means the ability of VPN sites to access public Internet. RFC4364 defines the
basic protocol regulations, including some methods for VPN to access Internet:
 Non-VRF Internet Access Mode
 VRF Internet Access Mode 3
82.1.1 Non-VRF Internet Access Mode
As demonstrated in the next figure, in non-VRF Internet Access Mode, PE routers communicate with Internet
gateways via non-VFP interface; and the Internet access traffic of VPN sites are forwarded according to the
global route table of PE routers. The CE and PE routers capable of accessing Internet have two connections,
one with the public network interface of PE (public network connection), the other with the priviate network
interface of PE (private network connection). The global route table of PE routes can contain the whole or part
of Internet routes, or only a default routes pointing to the Internet gateway. CE routers learn Interet routs via
the public network connection, and advertise to PE via the public network connection the globally registered
IP address sub-net routes in the VPN site, which will be advertised to the Internet gateway by PE and finally to
Internet. The Internet access traffic of VPN sites is also sent and received by the public network connection.
The private network connection between CE and PE is for the route learning of CE and advertising the private
network routes in tehe VPN. The VPN sites also communicate via private network connections, and forward
according to the VRF route table of PE routers. In this mode, the global and VRF rout table of PE routers are
completely isolated ; and the distribution of VPN routes and Internet routes are completely independent.
Figure 82-1 Non-VRF Internet Access Mode
PE1 P1
CE1
CE2
CE3
E 0
E1
E 3
E 2
VRFA
VRFB
P2
CE4
PE3
E 0
E 1
E3
VRFA
CE5
E 2
VRFB
MPLS Domain
internet
VRF Interface
Internet
Interface
VRF0
IGW