Appendix
E Encapsulation over PSN
Installation and Operation Manual
E-2
2BEncapsulation over Different PSN Types
ACE-3105, ACE-3205 Ver. 5.2
Ethernet header
PSN Header
Control Word
Payload
Figure
E-1. Basic PW Structure
E.2
Encapsulation over Different PSN Types
Pseudowire connections may be encapsulated in different formats, depending on
the type of PSN used in the application. The supported formats are:
MPLS/Layer-2, MPLS over IP, MPLS over GRE, UDP over IP, and PPPoE.
MPLS/Layer-2 Packet Format
The following figure illustrates the MPLS or Layer-2 encapsulation format:
DA
SA
Type
8100
VLAN
tag
Type
8847
Tunnel
label
PW
label
Control Word
Payload
Figure
E-2. MPLS/Layer-2 Encapsulation Format
Table
E-1. MPLS/Layer-2 Encapsulation Parameters
Parameter Name
Purpose
DA
Destination MAC address of the remote
peer or next hop unit. 6 bytes long.
SA
MAC address of the device. 6 bytes long.
Type 8100
If VLAN support is enabled, the Ethernet
packet type is set to 0x8100. 2 bytes long.
VLAN tag
If VLAN support is enabled, this tag includes
the VLAN ID and its priority; configured per
PW. 2 bytes long.
Type 8847
MPLS packet type – 0x8847. 2 bytes long.
Tunnel label
Label of the PW tunnel between
ACE-3105, ACE-3205 and the PE. This
parameter is manually configured per
PW/peer and per direction, or dynamically
learned using LDP. 4 bytes long.
A different value is possible for the RX and
TX directions (tunnel in/out).
PW label
Label of the Pseudowire; manually defined
per PW and per direction, or dynamically
learned using LDP. 4 bytes long.
Optional
Optional