173
VPNv4 route backup for a VPNv4 route
Figure 59 Network diagram
As show in
, configure FRR on the ingress node PE 1, and specify the backup next hop for
VPN 1 as PE 3. When PE 1 receives a VPNv4 route to CE 2 from both PE 2 and PE 3, it uses the
route from PE 2 as the primary link, and the route from PE 3 as the backup link.
Configure BFD for LSPs or MPLS TE tunnels on PE 1 to detect the connectivity of the public tunnel
from PE 1 to PE 2. When the tunnel PE 1
—
PE 2 operates correctly, traffic from CE 1 to CE 2 goes
through the path CE 1
—
PE 1
—
PE 2
—
CE 2. When the tunnel fails, the traffic goes through the path
CE 1
—
PE 1
—
PE 3
—
CE 2.
In this scenario, PE 1 is responsible for primary link detection and traffic switchover.
For more information about BFD for LSPs or MPLS TE tunnels, see "
."
VPNv4 route backup for an IPv4 route
Figure 60 Network diagram
As shown in
, configure FRR on the egress node PE 2, and specify the backup next hop for
VPN 1 as PE 3. When PE 2 receives an IPv4 route from CE 2 and a VPNv4 route from PE 3 (both
routes are destined for VPN 1 connected to CE 2), PE 2 uses the IPv4 route as the primary link, and
the VPNv4 route as the backup link.
PE 2 uses echo-mode BFD to detect the connectivity of the link from PE 2 to CE 2. When the link
operates correctly, traffic from CE 1 to CE 2 goes through the path CE 1
—
PE 1
—
PE 2
—
CE 2. When
the link fails, PE 2 switches traffic to the link PE 2—PE 3—CE 2, and traffic from CE 1 to CE 2 goes
through the path CE 1
—
PE 1
—
PE 2
—
PE 3
—
CE 2. This avoids traffic interruption before route
convergence completes (switching to the link CE 1—PE 1—PE 3—CE 2).
In this scenario, PE 2 is responsible for primary link detection and traffic switchover.
CE 2
CE 1
VPN 1
VPN 1
MPLS
backbone
PE 2
PE 1
PE 3
Primary link
Backup link
CE 2
CE 1
VPN 1
VPN 1
MPLS
backbone
PE 2
PE 1
PE 3
Primary link
Backup link
