The MPLS-OPS Archive

[Peter Macaulay <peter.macaulay@ZDSL.com>]

Can I apply a 32-bit MPLS label to Ethernet framed data and
then strip the LBL at the remove end and dump the complete
Ethernet frame with originall MAC addresses at into a remove
switch?  Where DA = destination address (MAC address), SA =
source address, TYPE = type field for layer 2 (L2), and IP =
Internet Protocol, ... , for Layer 3 (L3).

Figure 1:
 +------+------+------+----+----------+---------+----------+-----+
 | LBL  |  DA  |  SA  |TYPE|    IP    |   TCP   |   DATA   | CRC |
 +------+------+------+----+----------+---------+----------+-----+


Are most MPLS edge devices actually stripping the Ethernet Layer 2
and putting a label on the IP+TCP frame?

Figure 2:
 +------+----------+---------+----------+-----+
 | LBL  |    IP    |   TCP   |   DATA   | CRC |
 +------+----------+---------+----------+-----+

Does this diagram (Figure 3) work?  With the label between the L2
Ethernet and the L3 Internet Protocol.

Figure 3:
 +------+------+----+-------+---------+---------+----------+-----+
 |  DA  |  SA  |TYPE|  LBL  |   IP    |   TCP   |   DATA   | CRC |
 +------+------+----+-------+---------+---------+----------+-----+

Thanks.  Hope the ASCII artwork is clear.

/PETER MACAULAY






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