Juniper JUNOSE, Руководство по настройке

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prefix. Because BGP has only a default route in the VRF, it has to point that single
default route to a single uplink interface. All the Internet-bound traffic must flow out
of that interface.
You cannot configure traffic for one prefix to flow out of one uplink interface and
traffic to another prefix to flow out of another uplink interface. That behavior requires
a full default-free Internet routing table in the VRF, which is a complication that you
want to avoid.
Figure 101: Static Default Route for Internet Access
The following commands illustrate how to create a shared IP interface in the VRF
and point a default route to it:
host1(config)# virtual-router pe1:pe11
host1:pe1:pe11(config)# interface ip internet-access
host1:pe1:pe11(config-if)# ip share-interface atm2/1.3
host1:pe1:pe11(config-if)# ip address 10.1.1.3 255.255.255.255
host1:pe1:pe11(config-if)# exit
host1:pe1:pe11(config)# ip route 0.0.0.0 0.0.0.0 ip internet-access
See Shared IP Interfaces in the JUNOSe IP, IPv6, and IGP Configuration Guide , for
information about shared IP interfaces and default routes.
Configuring a Fallback Global Option
For the second solution you use the fallback global option on the PE–CE IP interface
(Figure 102 on page 458). If you have configured this option, the PE router
simultaneous performs two different lookups when a packet arrives from the CE
router. One lookup is in the IP routing table of the VRF; the other lookup is in the IP
routing table of the parent VR.
Providing Internet Access to and from VPNs
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Chapter 5: Configuring BGP-MPLS Applications