Cisco Cisco Packet Data Gateway (PDG) Guida Dell'Amministratore
BGP MPLS VPNs
ASR 5x00 as a PE ▀
Cisco ASR 5000 System Administration Guide ▄
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ASR 5x00 as a PE
Overview
In this scenario, the ASR 5x00 functions as a PE router sitting at the edge of the MPLS core. See the figure below.
Figure 18. ASR 5x00 as a PE
The ASR 5x00 eliminates the need for an ASBR or PE as shown in the first two scenarios. In this scenario, two main
requirements are introduced: IBGP functionality and MPLS label distribution protocols.
requirements are introduced: IBGP functionality and MPLS label distribution protocols.
The ASR 5x00 can be configured to add two labels:
an outer label learned from LDP or RSVP-TE (RSVP-Traffic Engineering)
an inner label learned from MP-iBGP
This solution supports traffic engineering and QoS initiated via the ASR 5x00.
Sample Configuration
In this example, VRFs are configured on the ASR 5x00 PE and pools are associated with VRFs. The ASR 5x00
exchanges VPN routes with its IBGP peers (PE routers) and learns the MPLS paths to reach PEs via LDP. The
ASR 5x00 forwards the packets to the next-hop with two labels – an inner label learned from PE and an outer label
learned from the next hop IBGP neighbor.
exchanges VPN routes with its IBGP peers (PE routers) and learns the MPLS paths to reach PEs via LDP. The
ASR 5x00 forwards the packets to the next-hop with two labels – an inner label learned from PE and an outer label
learned from the next hop IBGP neighbor.