Re: [mpls-linux-general] MPLS and virtual interfaces

[Alessandro De R. <ale...@ho...>]

James, thanks for your reply. This is the simple scenario I am trying to 
simulate with NCTUns:


Host1 -----------------LER1 ------------------- LER2 ---------------- Host2
   1.0.1.1          1.0.1.2     1.0.3.1        1.0.3.2    1.0.2.2       
1.0.2.1


Where LER1 should create the MPLS stack and LER2 should remove it. Host1 and 
Host2 respectively send and receive ipv4 packets.  I am trying to configure 
LER1 (from its rlogin shell) entering the following instructions:

mpls nhlfe add key 0
---> key:  0x00000002
mpls nhlfe change key 0x2 instructions push gen 1000 nexthop eth2 ipv4 
1.0.3.2
---> mpls nhlfe change key 0x2 instructions push gen 1000 nexthop tun4 ipv4 
1.0.3.2
---> RTNETLINK answers: Operation not permitted

Eth2 is the outgoing interface of LER1 (ip address 1.0.3.1) which 
corresponds to the virtual interface tun4. Exchanging eth2 with tun4 does 
not eliminate the RTNETLINK error.
The strange fact is that if I enter any other address which doesn't belong 
to my simulated network (i mean an invented address) I do not get the error. 
For example:

mpls nhlfe change key 0x2 instructions push gen 1000 nexthop eth2 ipv4 
153.153.153.153 (this network doesn't exist)
---> mpls nhlfe change key 0x2 instructions push gen 1000 nexthop tun4 ipv4 
153.153153.153
mpls nhlfe show
---> NHLFE entry key 0x00000002 mtu 1496 propagate_ttl
--->                     push gen 1000 set tun4 ipv4 153.153.153.153 (0 
bytes, 0 pkts, 0 dropped)

But obviously MPLS forwarding is then not enabled, since the network 
configuration is wrong.

The only thing I can think about is the way this simulator addresses 
packets: probably the point is not this, but every ip address in NCTUns is 
1.0.x.x and when a sending node 1.0.A.B has to send packets to a destination 
node 1.0.C.D, it uses A.B.C.D as destination address. And although this 
mechanism should be hidden to the user i can still see strange A.B.C.D 
addresses in my routing tables.
I don't know if these informations can be useful to you, but I am still not 
able to forward any MPLS packet in my simulated network. Can you help me in 
any way?
Alessandro De Rosa