Huawei Quidway NetEngine80E Configuration Manual page 64

HUAWEI NetEngine80E/40E Router
Configuration Guide - IP Routing
Applicable Environment
To speed up end-to-end traffic switchovers when a primary PW fails in a Layer 2 virtual private
network (L2VPN) that accesses a Layer 3 virtual private network (L3VPN), the system keeps
the L3VE sub-interface of the secondary PW Up. This mechanism spares the L3VE sub-interface
from negotiation of the Up state during the primary/secondary PW switchover, reducing traffic
loss and accelerating route convergence, especially when many L3VE sub-interfaces exist.
However, when the L3VE sub-interface is Up, the system generates a network segment route.
The network segment route will be selected, because a direct route has the highest priority.
Because the connected PW is the secondary PW, the network segment route becomes a black-
hole route, and traffic cannot be forwarded between the CSGs. To address this problem,
configure the device to deactivate the IPv6 network segment route that corresponds to the L3VE
sub-interface.
As shown in
CSGs, while Border Gateway Protocol (BGP) virtual private network version 6 (VPNv6) peer
relationships are set up between the AGGs and radio network controller site gateways (RSGs).
L3VE sub-interfaces are configured on the AGGs, and VPN instances are bound to the L3VE
sub-interfaces so that the CSGs can access the L3VPN. BGP is configured on the AGGs to import
direct routes between the CSGs and AGGs. These direct routes are converted to BGP VPNv6
routes and advertised to the RSGs.
Figure 1-8 Networking of L2VPN accessing the L3VPN
NodeB
NodeB
In most cases, if CSG1 needs to communicate with CSG2, CSG1 forwards data to AGG1 through
the primary PW (PW1). PW4 on AGG1 is the secondary PW, but the L3VE sub-interface is Up.
AGG1 generates and selects a network segment route because a direct route has a higher priority
than a BGP VPNv6 route learned from AGG2. However, AGG1 is not the master device of
CSG2 and does not have the Media Access Control (MAC) addresses stored on CSG2. To
forward the data, AGG1 sends a Neighbor Solicitation (NS) packet to CSG2. CSG2 sends a
Neighbor Advertisement (NA) packet through the primary PW (PW3). The NA packet reaches
AGG2, instead of AGG1. AGG1 cannot learn the MAC addresses stored on CSG2 or forward
traffic to CSG2. The network segment route from AGG1 to CSG2 becomes a black-hole route.
Issue 02 (2014-09-30)
Figure 1-8, PWs are set up between the access aggregation gateways (AGGs) and
CSG1 AGG1
PW1
PW2
PW4
PW3
CSG2 AGG2
Primary PW
Secondary PW
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1 IP Routing Basic Configuration
RSG1
BGP/MPLS IPv6 VPN
RSG2
Data flow
NS packet
NA packet
RNC
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