Sample Configurations - Cisco 3845 - Security Bundle Router Software Manual
Software configuration guide
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Configuring MPLS VPNs
A customer (Fast Ethernet) port on switch PE1 is configured for routed operation in a VPN. The port
uses static routing or a routing protocol (RIP, OSPF, EIGRP, or BGP) to forward packets. MP-BGP is
configured over the PE1 switch ES port with a route distinguisher that is associated with the customer's
VPN. MP-BGP is configured to redistribute the routes and their associated VPN labels over the ES port
that is using this route distinguisher.
The packet flow follows these steps:
Provider-edge switch PE1 (which could be a Metro switch) receives a packet from the customer switch
Step 1
at site 1. The switch determines from the lookup table that the VRF is a VLAN running MPLS and uses
the MPLS lookup table to determine what to do with the packet. The MPLS lookup table contains the
peer LSR as the destination MAC address and the local interface as the source MAC address.
PE1 finds a BGP route with the appropriate next hop and labels, adds the appropriate labels to the packet,
Step 2
and forwards the packet out of the ES port to the next hop router (P3).
The P3 router receives the packet and forwards it over the MPLS-VPN network, based on the packet's
Step 3
top label—the interior gateway protocol (IGP) label—and then removes the top label.
Step 4
PE3 receives the packet, removes the MPLS encapsulation, and forwards the packet by using the VRF
interface associated with the VPN label contained in the packet that has the customer-edge switch CE2
as the destination.
Sample Configurations
This example shows a Layer 3 VPN configured on an EFP:
Switch# show run interface g0/24
Building configuration...
Current configuration : 226 bytes
!
interface GigabitEthernet0/24
port-type nni
switchport trunk allowed vlan none
switchport mode trunk
service instance 1 ethernet
encapsulation dot1q 20
rewrite ingress tag pop 1 symmetric
bridge-domain 100
!
end
This example shows a Layer 3 VPN configured on a switched virtual interface (SVI):
Switch# show run interface vlan 100
Building configuration...
Current configuration : 82 bytes
!
interface Vlan100
ip vrf forwarding A
ip address 100.1.1.1 255.255.255.0
end
This example shows a Layer 3 VPN configured using non-switchport port mode:
Switch# show run interface g0/24
interface GigabitEthernet0/24
Cisco ME 3800X and 3600X Switch Software Configuration Guide
34-16
Chapter 34
Configuring MPLS, MPLS VPN, MPLS OAM, and EoMPLS
OL-23400-01
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