wikisrc/users/kefren/mpls.mdwn - view

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Thu Nov 1 09:21:52 2012 UTC (9 years, 9 months 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.