Cisco Cisco Packet Data Interworking Function (PDIF) Guía De Administador
BGP MPLS VPNs
▀ Introduction
▄ Cisco ASR 5500 System Administration Guide
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Introduction
Service providers require the ability to support a large number of corporate Access Point Names (APNs) which have a
number of different addressing models and requirements. The ASR 5x00 uses BGP MPLS Layer 3 VPNs to segregate
corporate customer APNs in a highly scalable manner. This solution conforms to RFC 4364 – BGP/MPLS IP Virtual
Private Networks (VPNs).
number of different addressing models and requirements. The ASR 5x00 uses BGP MPLS Layer 3 VPNs to segregate
corporate customer APNs in a highly scalable manner. This solution conforms to RFC 4364 – BGP/MPLS IP Virtual
Private Networks (VPNs).
The BGP/MPLS solution supports the following scenarios:
The ASR 5x00 also supports VPNv6 as described in RFC 4659 – BGP-MPLS IP Virtual Private Network (VPN)
Extension for IPv6 VPN. See
Extension for IPv6 VPN. See
MPLS-CE Connected to PE
In this scenario the ASR 5x00 functions as an MPLS-CE (Customer Edge) network element connected to a Provider
Edge (PE) Label Edge Router (LER), which in turn connects to the MPLS core (RFC 4364). See the figure below.
Edge (PE) Label Edge Router (LER), which in turn connects to the MPLS core (RFC 4364). See the figure below.
Figure 15. ASR 5x00 MPLS-CE to PE
The MPLS-CE functions like a PE router within its own Autonomous System (AS). It maintains Virtual Routing and
Forwarding (VRF) routes and exchanges VPN route information with the PE via an MP-eBGP (Multi-Protocol-external
BGP) session.
Forwarding (VRF) routes and exchanges VPN route information with the PE via an MP-eBGP (Multi-Protocol-external
BGP) session.
The PE is also configured with VRFs and exchanges VPN routes with other PEs in its AS via MP-iBGP (Multi-
Protocol-internal BGP) connections and the MPLS-CE via an MP-eBGP connection.
Protocol-internal BGP) connections and the MPLS-CE via an MP-eBGP connection.
The EBGP connection allows the PE to change next-hop IP addresses and labels in the routes learned from IBGP peers
before advertising them to the MPLS-CE. The MPLS-CE in this case uses only MP-eBGP to advertise and learn routes.
Label Distribution Protocol (LDP) and Resource Reservation Protocol (RSVP) are not required because of direct-
connect EBGP peering. The MPLS-CE in this scenario pushes/pops a single label (learned over the MP-eBGP
connection) to/from the PE.
before advertising them to the MPLS-CE. The MPLS-CE in this case uses only MP-eBGP to advertise and learn routes.
Label Distribution Protocol (LDP) and Resource Reservation Protocol (RSVP) are not required because of direct-
connect EBGP peering. The MPLS-CE in this scenario pushes/pops a single label (learned over the MP-eBGP
connection) to/from the PE.