#Some quick info about MPLS:
You need to compile your kernel with options MPLS and psuedo-device ifmpls
For pure LSR - that only switch labels without encap/decap from other protocols (e.g. INET) you need only to work on routing table. For example:
# route add -mpls 41 -tag 25 -inet 193.28.151.97
add host 41: gateway 193.28.151.97
# route add -mpls 42 -tag 30 -inet 193.28.151.97
add host 42: gateway 193.28.151.97
# route add -mpls 51 -tag 25 -inet 193.28.151.97
add host 51: gateway 193.28.151.97
Translation of first line: if it receives an MPLS frame with label 41 forward it to INET next-hop 193.28.151.97, tagged with label 25
You also need to tweak sysctl to accept and forward MPLS:
# sysctl -w net.mpls.accept=1
net.mpls.accept: 0 -> 1
# sysctl -w net.mpls.forwarding=1
net.mpls.forwarding: 0 -> 1
Verify routes with route get or better with netstat -nrT:
...
MPLS:
Destination Gateway Flags Refs Use Mtu Tag Interface
41 193.28.151.97 UGHS 0 37241 - 25 sk0
42 193.28.151.97 UGHS 0 0 - 30 sk0
51 193.28.151.97 UGHS 0 0 - 25 sk0
#Interacting with other protocols
If you want to also decapsulate/encapsulate from MPLS to some other protocol (like INET or INET6), you have to create an mpls interface and put in up.
# ifconfig mpls0 create up
After that create routes like this - use -ifa flag in order to avoid self-generated packets having source address 1.1.1.1, but route them through mpls0 interface.
# route add 204.152.190.0/24 -ifa 193.28.151.105 -ifp mpls0 -tag 25 -inet 193.28.151.97
add net 204.152.190.0: gateway 193.28.151.97
Verify the route:
# route -n get 204.152.190.0/24
route to: 204.152.190.0
destination: 204.152.190.0
mask: 255.255.255.0
gateway: 193.28.151.97
Tag: 25
local addr: 193.28.151.105
interface: mpls0
flags:
recvpipe sendpipe ssthresh rtt,msec rttvar hopcount mtu expire
0 0 0 813 344 0 0 0
sockaddrs:
or with netstat -rT:
...
204.152.190/24 193.28.151.97 UGS 0 95362 - 25 mpls0
...
Test if it's working using traceroute -M. Notice first hop is reporting label 25.
# traceroute -M 204.152.190.12
traceroute to 204.152.190.12 (204.152.190.12), 64 hops max, 40 byte packets
1 shaitan.girsa.ro (193.28.151.97) 2.892 ms 1.957 ms 1.992 ms [MPLS: Label 25 Exp 0]
2 b4-vlan811.girsa.ro (193.28.151.82) 1.988 ms 1.961 ms 1.989 ms [MPLS: Label 27 Exp 0]
3 80.97.219.81 (80.97.219.81) 1.990 ms 1.974 ms 2.009 ms
4 vlan103.cr3-sw.buch.artelecom.net (80.97.199.1) 2.651 ms 2.280 ms 3.663 ms
5 10.0.241.189 (10.0.241.189) 33.944 ms 34.011 ms 33.869 ms [MPLS: Label 21669 Exp 0]
6 10.0.240.22 (10.0.240.22) 33.946 ms 33.689 ms 33.929 ms
7 20gigabitethernet4-3.core1.fra1.he.net (80.81.192.172) 35.930 ms 35.926 ms 35.917 ms
8 10gigabitethernet1-2.core1.par1.he.net (72.52.92.89) 43.940 ms 45.900 ms 47.916 ms
9 10gigabitethernet1-3.core1.lon1.he.net (72.52.92.33) 59.901 ms 51.888 ms 51.913 ms
10 10gigabitethernet4-4.core1.nyc4.he.net (72.52.92.241) 119.808 ms 119.780 ms 119.800 ms
11 10gigabitethernet1-2.core1.chi1.he.net (72.52.92.102) 141.755 ms 143.748 ms 149.756 ms
12 he.ord1.isc.org (209.51.161.18) 143.756 ms 143.757 ms 141.755 ms
13 iana.r1.ord1.isc.org (199.6.0.1) 145.831 ms 141.747 ms 143.762 ms
14 int-0-0-1-8.r1.pao1.isc.org (149.20.65.157) 201.653 ms 205.650 ms 201.650 ms [MPLS: Label 16005 Exp 0]
15 int-0-0-1-0.r2.sql1.isc.org (149.20.65.10) 201.663 ms 201.645 ms 201.664 ms
16 www.netbsd.org (204.152.190.12) 199.676 ms 201.652 ms 201.673 ms
I'm working on [[LDP]] daemon, it should be available in src tree in a couple of months. You may still want to test the beta.