Creating Labels Per Fec - Juniper JUNOSE SOFTWARE FOR E SERIES 11.3.X - BGP AND MPLS CONFIGURATION GUIDE 2010-10-12 Configuration Manual

Creating Labels per FEC

ip mpls forwarding-mode label-switched
Copyright © 2010, Juniper Networks, Inc.
By default, the router minimizes the number of stacked labels to be managed by
generating a single label for all BGP routes advertised by a given VRF; this is a per-VRF
label. Upon receiving traffic for a per-VRF label, the router performs a label pop and a
route lookup to forward the traffic to the next hop.
You can use the ip mpls forwarding-mode label-switched command to configure the
router to generate a label for each different FEC that a BGP route points to in the VPN;
this is a per-FEC label. Issuing this command enables you to avoid a route lookup for
traffic destined for CE routers, because in this mode traffic is label switched to the
corresponding next hop over that interface; a route lookup is not performed.
The route for which a label is allocated can be an ECMP route; in that case, the
label-switched traffic uses ECMP.
For the following types of routes, the router always generates a per-VRF label and
forwards traffic after a route lookup (rather than label switching the traffic without a
route lookup) regardless of the status of this command:
Local connected interfaces redistributed into BGP, regardless of the interface type.
BGP redistributed routes that point to loopback interfaces.
The following commands configure a router where BGP is running in VRF pe11 and static
and connected routes are redistributed into the VRF:
host1(config)#ip vrf pe11
host1(config-vrf)#ip mpls forwarding-mode label-switched
host1(config-vrf)#ip route vrf pe11 10.3.4.5 255.255.255.255 fastEthernet 0/1
host1(config-vrf)#ip route vrf pe11 10.1.1.1 255.255.255.255 loopback 1
host1(config-vrf)#exit
host1(config)#router bgp 100
host1(config-router)#address-family ipv4 unicast vrf pe11
host1(config-router-af)#exit
host1(config-router)#no auto-summary
host1(config-router)#no synchronization
host1(config-router)#redistribute static
host1(config-router)#redistribute connected
For each connected route that is redistributed into the VRF and advertised across the
BGP/MPLS VPN, the router assigns a per-VRF label rather than a per-FEC label.
The static route 10.1.1.1/32 points to loopback interface 1. BGP therefore advertises this
static route with a per-VRF label.
Use to generate a label for each different FEC pointed to by a BGP route.
For some types of routes, issuing this command has no effect on the labels created;
they are always per-VRF labels.
Example
Chapter 6: Configuring BGP-MPLS Applications
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