Mpls L3Vpn Load Balance - Zte ZXR10 8900 Series User Manual

Chapter 3 MPLS L3VPN Configuration
Meanwhile, CE transmits information of VPN-IP and corresponding
labels (labels on VPN, shortened into internal-layer label as fol-
lows) by adopting BGP between PEs.
Traditional IGP is adopted to learn routing information from each
other between PE and P routers. LDP is adopted to bind routing
information and labels (labels in the backbone network, shortened
as external-layer label as follows).
In this case, basic network topology and routing information of CE,
PE and P routers have already been formed. A PE router has rout-
ing information of the backbone network and routing information
of each VPN.
When a CE user on a VPN enters the network, system can identify
to which VPN CE belongs on the interface between CE and PE, and
will further read the next-hop address information in the routing
table of the VPN. In addition, forwarded packets will be marked
with a VPN label (internal layer label). In this case, the next-hop
address obtained is the address of a PE that is the peer of this PE.
To reach the destination PE, the routing information of backbone
network should be read from the source PE to obtain the address
of the next P router, and meanwhile, forwarded user's packets will
be tagged with a backbone network label (external layer label).
In backbone network, all P routers after the source PE read the
external layer label to determine the next hop. Therefore, only
simple label switching is performed on the backbone network.
When a packet reaches the last P router before arriving at the
destination PE, external layer label will be cancelled. After packet
reaches the destination PE, PE will read internal layer label, find
the next-hop CE in the corresponding VRF, send packet to related
interface and further transfer data to CE network of VPN.

MPLS L3VPN Load Balance

MPLS L3VPN load balance is to implement load sharing and protect
links when switches access to VPN through PE. As shown in Figure
18, all VPN service traffic (for example, VPN traffic from P0 and P1)
goes to P4 through P2 and P3. After filtration, service traffic goes
back to P0 and P1 from P4 and then goes to Internet. For VPN A,
traffic from user A and user B to P2 and P3, and traffic going back
to P2 and P3 from P4 are load balanced.
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