[mpls-linux-general] Problems with MPLS packets

[Daniel G. C. <da...@on...>]

(sorry for my english)
I'm making a MPLS network with PCs with Linux-MPLS 1.0 over kernel 2.4.13 in
a Red Hat Linux 7.1 system. I have configured a MPLS network with three PCs
and it seems to work properly, but when I use ethereal to capture some
packets I watch some problems.
I'm testing with ping command, and when I make ping in one way it works
properly, it puts the MPLS labels over the IP packets, but in the other way
it doesn't put the MPLS labels it sends it as normal IP packets.
Also, I have test it with the 2 host network that is in the example of the
Linux-MPLS packet, but it continues happenning. ¿Is this a normal behavior
of Linux-MPLS?

The scenario is:

     160.20.20.1              160.20.20.2
     A   -------------------------------- B
            eth0                        eth1

        160.20.20.0 /255.255.252.0

And the mpls configuration is:

On A
-------
ifconfig eth0 160.20.20.1 netmask 255.255.252.0 up
route add -host 160.20.20.2 gw 160.20.20.2
mplsadm -A -B -O gen:10:eth0:ipv4:160.20.20.2 -f 160.20.20.2/32
mplsadm -A -I gen:20:0
mplsadm -L eth0:0

On B
-------
ifconfig eth1 160.20.20.2 netmask 255.255.252.0 up
route add -host 160.20.20.1 gw 160.20.20.1
mplsadm -A -B -O gen:20:eth0:ipv4:160.20.20.1 -f 160.20.20.1/32
mplsadm -A -I gen:10:0
mplsadm -L eth1:0


The packets from B to A are MPLS, but the replys of ping (or the request of
ping) from A to B are not MPLS labeled packets.

And when I make ping from B to A, in ethereal (in A) appear Bogus IP headers
(I don't know what exactly are they) but they are IP packets with some MPLS
labels inside, and after the bogus IP, in ethereal capture, appear the
normal IP reply without MPLS label.

When I make ping from A to B, in ethereal (in B) appear that the reply from
B are MPLS-IP labeled packets, but the requests from A are normal IP
packets. And in ethereal (in A) capture list appear that are malformated IP
headers (with unknown MPLS labels inside), and after this it sends normal IP
packets (the ping reply).

The installation in A and B are the same (they are images maked with Norton
Ghost), the PCs are exactly the same (the hardware is the same). In A eth0
is a 3Com card, and in B eth1 is a Realtek card but it isn't the problem
because I have test it with B and other PC (same hardware and SO
installation) that have the same ethernet card in eth1, too, and the problem
is the same.

Perhaps, Ethereal don't work properly? or, Is this the normal behavior of
ping? I don't know why it happens, ¿can someone help me? thanks.

Best regards, Dani.