File:  [NetBSD Developer Wiki] / wikisrc / users / kefren / mpls.mdwn
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Thu Nov 1 09:21:52 2012 UTC (17 months, 3 weeks ago) by wiki
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web commit by kefren: minor corrections, sync info with reality

#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 to work on routing table, ONLY. For example:

<pre># 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</pre>

Translation of first line: if it receives an MPLS frame with label 41 forward it to INET next-hop 193.28.151.97, but switch (change) label 41 with label 25

You also need to tweak sysctl to accept and forward MPLS:

<pre># sysctl -w net.mpls.accept=1
net.mpls.accept: 0 -> 1
# sysctl -w net.mpls.forwarding=1
net.mpls.forwarding: 0 -> 1</pre>


Verify routes with route get or better with netstat -nrT:

<pre>
...
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
</pre>

#Interacting with other protocols

If you want to also decapsulate/encapsulate from MPLS to some other protocol (like INET or INET6), then you have to create an mpls interface and put in up state.


<pre>
# ifconfig mpls0 create up
</pre>

After that, create routes using ifa flag in order to specify the source interface (used for source IP Address of host generated packets), but route them through mpls0 interface.

<pre>
# 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
</pre>

Verify the route:

<pre>
# 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: <UP,GATEWAY,DONE,STATIC>
 recvpipe  sendpipe  ssthresh  rtt,msec    rttvar  hopcount      mtu     expire
       0         0         0       813       344         0         0         0 
sockaddrs: <DST,GATEWAY,NETMASK,IFP,IFA,TAG>
</pre>

or with netstat -rT:
<pre>
...
204.152.190/24     193.28.151.97      UGS         0    95362      -      25 mpls0
...
</pre>

Test if it's working using traceroute -M. Notice first hop is reporting label 25.

<pre>
# 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
</pre>

See also [[LDP]] wiki page.

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