HP 12500 Series Configuration Manual page 133

Tunnel—A tunnel, usually an MPLS tunnel, is a direct channel between a local PE and the peer PE
•
for transparent data transmission in-between. It is used to carry PWs. A tunnel can carry multiple
PWs.
• Encapsulation—Packets transmitted over a PW use the standard PW encapsulation formats and
technologies: Ethernet and VLAN.
PW signaling—The PW signaling protocol is the fundament of VPLS. It is used for creating and
•
maintaining PWs and automatically discovering VSI peer PE. Two PW signaling protocols are
available: LDP and BGP.
QoS—Quality of Service (QoS) is implemented by mapping the preference information in the
•
packet header to the QoS preference information transferred on the public network.
Figure 28 shows a typical VPLS networking scenario.
Figure 28 Network diagram for VPLS
Site 2
VPN 1
VPN 2
Site 3
CAUTION:
Do not enable STP or configure RRPP at the private network side of the PEs. Otherwise, a broadcast storm
will occur, crashing down the network. For more information about STP, see
Configuration Guide
MAC address learning and flooding
VPLS provides reachability by MAC address learning. Each PE maintains a MAC address table.
• Source MAC address learning
MAC address learning includes the following parts:
Remote MAC address learning associated with PWs
A PW consists of two unidirectional VC LSPs. A PW is up only when both of the VC LSPs are
up. When the inbound VC LSP learns a new MAC address, the PW needs to map the MAC
address to the outbound VC LSP.
Local MAC address learning of interfaces directly connected to users
This refers to learning source MAC addresses from Layer 2 packets originated by CEs. This
occurs on the corresponding VSI interfaces.
Tunnel
PW
AC
Forwarder
CE 3
CE 4
. For more information about RRPP, see
CE 1
MPLS backbone
P
PE 1
PE 2
PWSignaling
125
Site 1
VPN 1
VPN 2
CE 2
Layer 2—LAN Switching
High Availability Configuration Guide
.