List of Figures

Figure 1: Routers in a VPN

Figure 2: Logical Interface per Router in a Virtual-Router Routing Instance

Figure 3: BGP Route Target Filtering Enabled for a Group of VPNs

Figure 4: Network Topology of Site of Origin Example

Figure 5: Layer 2 VPN Connecting CE Routers

Figure 6: Relationship Between the Site Identifier and the Remote Site ID

Figure 7: Example of a Simple Full-Mesh Layer 2 VPN Topology

Figure 8: VPN Attributes and Route Distribution

Figure 9: Overlapping Addresses Among Different VPNs

Figure 10: Route Distinguishers

Figure 11: VRF Tables

Figure 12: Route Distribution Within a VPN

Figure 13: Distribution of Routes from CE Routers to PE Routers

Figure 14: Distribution of Routes Between PE Routers

Figure 15: Distribution of Routes from PE Routers to CE Routers

Figure 16: Using MPLS LSPs to Tunnel Between PE Routers

Figure 17: Label Stack

Figure 18: Multicast Topology Overview

Figure 19: OSPF Sham Link

Figure 20: GRE Tunnel Configured Between the Local CE Router and the PE Router

Figure 21: GRE Tunnel Configured Between the Remote CE Router and the PE Router

Figure 22: Layer 3 VPN Topology for ping and traceroute Examples

Figure 23: Example of a Simple VPN Topology

Figure 24: Example of a Hub-and-Spoke VPN Topology with One Interface

Figure 25: Example of a Hub-and-Spoke VPN Topology with Two Interfaces

Figure 26: Route Distribution Between Two Spoke Routers

Figure 27: Example of an LDP-over-RSVP VPN Topology

Figure 28: Label Pushing and Popping

Figure 29: Application-Based Layer 3 VPN Example Configuration

Figure 30: Example of a Configuration Using an OSPF Domain ID

Figure 31: Example of an Overlapping VPN Topology

Figure 32: PE Routers A and D Connected by a GRE Tunnel Interface

Figure 33: GRE Tunnel Between the CE Router and the PE Router

Figure 34: ES Tunnel Interface (IPsec Tunnel)

Figure 35: PE Router Does Not Provide Internet Access

Figure 36: PE Router Connects to a Router Connected to the Internet

Figure 37: Routing VPN and Internet Traffic Through Different Interfaces

Figure 38: Example of Internet Traffic Routed Through Separate Interfaces

Figure 39: VPN and Outgoing Internet Traffic Routed Through the Same Interface and Return Internet Traffic Routed Through a Different Interface

Figure 40: Interface Configured to Carry Both Internet and VPN Traffic

Figure 41: VPN and Internet Traffic Routed Through the Same Interface

Figure 42: Internet Traffic Routed Through a Separate NAT Device

Figure 43: Internet Traffic Routed Through a NAT Example Topology

Figure 44: Internet Access Through a Hub CE Router Performing NAT

Figure 45: Internet Access Provided Through a Hub CE Router

Figure 46: Two Hub CE Routers Handling Internet Traffic and NAT

Figure 47: Simple MVPN Topology

Figure 48: Flooding a Packet with an Unknown Destination to All PE Routers in the VPLS Instance

Figure 49: BGP and LDP Signaling for a VPLS Routing Instance

Figure 50: VPLS Label Block Structure

Figure 51: Label Mapping Example

Figure 52: Flooding Unknown VPLS Traffic Using Ingress Replication

Figure 53: Flooding Unknown VPLS Traffic Using a Point-to-Multipoint LSP

Figure 54: Router 1 to Router 3 Topology

Figure 55: Interprovider VPN Network Topology

Figure 56: Carrier-of-Carriers VPN Architecture

Figure 57: Network Topology for the Interprovider VPN Example

Figure 58: Network Topology of Interprovider VPN Example—Multihop MP-EBGP

Figure 59: Carrier-of-Carriers VPN Example Network Topology

Figure 60: Components of a Layer 2 Circuit

Figure 61: ATM Trunking on Layer 2 Circuits

Figure 62: Layer 2 Circuits Using Protect Interfaces