[mpls-linux-general] binding label/FEC to hosts

[krishnan n. <shy...@my...>]

Hello,

    When the routing table contains net entries, say,
    192.168.1.0, how do we set up a label/FEC mapping
    to a specific host, say, 192.168.1.1?

    Assuming we would want to create a Label Switch
    Path to a specific host and also don't want to
    make the the host routing entry in every LSR
    in the path - the net entry to reach this host already
    exists - how do we do it? Is it at all possible?

    Currently, we are able to create FEC using the net
    entry:
    mplsadm -B ... -f 192.168.1.0/24
    What we would like to do is to have a label to a host:
    mpsadm -B ... -f 192.168.1.2/25

    From the code (i'm on *very* shaky ground here) it looks
    a bit hard to write host FEC to a n/w route in fib. Traced
    it down to:
    net/mpls/mpls_out_info.c: mpls_bind_out2fec
        ...
        ...
        if(fib_add_proto_data(&k,&res,AUX_PROTO_DATA_MPLS) == 0) ...

    and in:
    net/ipv4/fib_hash.c:fn_hash_add_proto_data()
        ...
        ...
        f->fn_proto_data[proto_num] = res->proto_data[proto_num];
        /* ??  appears, only one proto data may be added per proto
           num, even though fn_proto_data is declared *[] */

    It appears to be easier to hold this FEC in the mpls_out_info
    _tree list ?

    I am curious to know:
    a) Would it be useful to be able to bind a label to a host given
       only a net entry in the routing table?
    b) does the Forwarding Information Base semantics support this
       at all?
    c) Alternatively, does it make sense to map a net entry to a
       host entry. What i mean is, if the user specifies a host
       entry ( mplsadm -f 192.168.1.2/32  in the example above)
       would it make sense to silently map this to 192.168.1.0/24?
       since only 192.168.1.0 entry exists in the routing table?
    d) (unrelated question) where can i get more information about the
       kernel mutiple table support / Forwarding Information Base?

thank you,
shyam


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