Pe-Pe Behavior; Mpls Data Plane Behavior; Providing Ipv4 Vpn Services Across Multiple Autonomous Systems - Juniper BGP - CONFIGURATION GUIDE V 11.1.X Configuration Manual

RIB with the stacked label L1, which MPLS allocated for this prefix. The default IPv6
VRF label is L1.
PE PE Behavior
PE 1 advertises the VPNv6 prefixes in the MP_REACH_NLRI attribute of the update
messages sent to its MP-IBGP peer, PE 2. The AFI and SAFI values are negotiated for
VPNv6. The AFI value is 2 for IPv6, and the SAFI value is 128 for MPLS-labeled
VPN-IPv6.
When PE 2 receives the VPNv6 prefix 6001:0430::/48 with label L1, it imports the
prefix into VRF B because VRF B's import route target matches the route target
received in the MP-BGP update. For all labeled VPNv6 prefixes installed in VRF B
that come from the same endpoint on PE 1 (loopback FFFF::1.1.1.1/128), a single
dynamic IPv6 interface stacked on top of an MPLS tunnel head is created in VRF B
regardless of the number of different stacked labels associated with each VPNv6
prefix. The prefix is then installed in VRF B's routing table as pointing to this dynamic
IPv6 interface.
If PE 1 is not running either JUNOSe or JUNOS software, each VPNv6 prefix usually
has a different stacked label value sent in the MP-BGP update. If an implementation
allocates one VPN interface per received stacked label, this behavior might potentially
become a scaling issue if many dynamic IPv6 interfaces are allocated to resolve each
VPNv6 prefix in VRF B.

MPLS Data Plane Behavior

When PE 2 receives a data packet from CE 2 destined for the 6001:0430::/48 network,
the router detects a native IPv6 packet on its link to CE 2. PE 2 does a lookup in its
VRF B IPv6 routing table, prepends labels L2 and L1 to the IPv6 header, and then
forwards this packet on its core-facing IPv6 dynamic interface. When the P router
receives this packet, it performs a lookup on L2 and label switches the packet toward
PE 1. The P router either replaces L2 with another label or pops that label if PE 1
requested PHP.
When PE 1 receives the packet on its core-facing interface, it pops all the labels, and
performs a lookup in the IPv6 table of VRF A (which is associated with L1) using the
destination address in the IPv6 header. After that, PE 1 forwards the IPv6 packet out
to CE 1 on the IPv6 link.

Providing IPv4 VPN Services Across Multiple Autonomous Systems

Inter-AS services, sometimes known as interprovider services, support VPNs that
cross AS boundaries. VPNs might need to cross AS boundaries because of a customer
deployment that involves geographically separated ASs. The VPN sites can be provided
by the same service provider or by different service providers as part of a joint VPN
service offering. Inter-AS services are also useful to service providers that use
confederations of sub-ASs to reduce the IBGP mesh inside the AS.
You can support these inter-AS services in three different ways, known as inter-AS
option A, option B, and option C. Option C is preferred to option B; option B is
Providing IPv4 VPN Services Across Multiple Autonomous Systems
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