HPE FlexFabric 5950 Series Configuration Manual page 198

For packets between customer networks to travel through the Level 1 carrier, the PE of the Level 1
carrier and the CE of the Level 2 carrier must assign labels to the backbone networks of the Level 2
carrier. The CE of the Level 2 carrier is a PE within the Level 2 carrier network.
Follow these guidelines to assign labels:
•
If the PE and the CE are in the same AS, you must configure IGP and LDP between them. If
they are in different ASs, you must configure MP-EBGP to assign labels to IPv4 unicast routes
exchanged between them.
•
You must enable MPLS on the CE of the Level 2 carrier regardless of whether the PE and CE
are in the same AS.
A Level 2 carrier can be an ordinary ISP or an MPLS L3VPN service provider.
F igure 54, when the customer carrier is an ordinary ISP, its PEs and CEs run IGP to
As shown in
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communicate with each other. The PEs do not need to run MPLS. PE 3 and PE 4 exchange
customer network routes (IPv4 unicast routes) through an IBGP session.
Figure 54 Scenario where the Level 2 carrier is an ISP
As shown in F igure 55, when the customer carrier is an MPLS L3VPN service provider, its PEs and
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CEs must run IGP and LDP to communicate with each other. PE 3 and PE 4 exchange customer
network routes (VPN-IPv4 routes) through an MP-IBGP session.
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