Re: [mpls-linux-general] Problems with MPLS packets

[James R. L. <jl...@mi...>]

This is a know problem.  It is not really a corrupted packet it just look=
s
that way from ethereal/tcpudmp etc.

From the "NOTE" file:
-mpls packets appear to be corrupted when running tcpdump or the like on
 an LER (the packets are not really corrupted, tcpdump is getting an inva=
lid
 version of the packets)=20

Jim


On Wed, Apr 10, 2002 at 02:22:00PM +0200, Daniel Gregorio Catalan wrote:
> (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. =BFIs this a normal beh=
avior
> of Linux-MPLS?
>=20
> The scenario is:
>=20
>      160.20.20.1              160.20.20.2
>      A   -------------------------------- B
>             eth0                        eth1
>=20
>         160.20.20.0 /255.255.252.0
>=20
> And the mpls configuration is:
>=20
> 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
>=20
> 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
>=20
>=20
> The packets from B to A are MPLS, but the replys of ping (or the reques=
t of
> ping) from A to B are not MPLS labeled packets.
>=20
> And when I make ping from B to A, in ethereal (in A) appear Bogus IP he=
aders
> (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.
>=20
> 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 malformate=
d IP
> headers (with unknown MPLS labels inside), and after this it sends norm=
al IP
> packets (the ping reply).
>=20
> The installation in A and B are the same (they are images maked with No=
rton
> Ghost), the PCs are exactly the same (the hardware is the same). In A e=
th0
> is a 3Com card, and in B eth1 is a Realtek card but it isn't the proble=
m
> 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 pr=
oblem
> is the same.
>=20
> Perhaps, Ethereal don't work properly? or, Is this the normal behavior =
of
> ping? I don't know why it happens, =BFcan someone help me? thanks.
>=20
> Best regards, Dani.
>=20
>=20
> _______________________________________________
> mpls-linux-general mailing list
> mpl...@li...
> https://lists.sourceforge.net/lists/listinfo/mpls-linux-general

--=20
James R. Leu