HPE FlexNetwork 5510 HI Series, Руководство по настройке Mpls

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The BGP AS number substitution function allows physically dispersed CEs to use the same AS
number. The function is a BGP outbound policy and affects routes to be advertised.
With the BGP AS number substitution function, when a PE advertises a route to a CE, if an AS
number identical to that of the CE exists in the AS_PATH of the route, the PE replaces it with its own
AS number.
After you enable the BGP AS number substitution function, the PE performs BGP AS number
substitution for all routes and re-advertises them to connected CEs in the peer group.
Figure 58 Application of BGP AS number substitution
As shown in Figure 58 , both Site and Site 2 use the AS number 800. AS number substitution is
enabled on PE 2 for CE 2. Before advertising updates received from CE 1 to CE 2, PE 2 substitutes
its own AS number 100 for the AS number 800. In this way, CE 2 can correctly receive the routing
information from CE 1.
However, the AS number substitution function also introduces a routing loop in Site 2 because route
updates originated from CE 3 can be advertised back to Site 2 through PE 2 and CE 2. To remove
the routing loop, you can configure a routing policy on PE 2 to add the SoO attribute to route updates
received from CE 2 and CE 3 so that PE 2 does not advertise route updates from CE 3 to CE 2.
NOTE:
The device does not support adding the SoO attribute to routes.
MPLS L3VPN FRR
MPLS L3VPN Fast Reroute (FRR) is applicable to a dual-homed scenario, as shown in Figure 59 . By
using BFD to detect the primary link, FRR enables a PE router to use the backup link when the
primary link fails. The PE router then selects a new optimal route, and uses the new optimal route to
forward traffic.
MPLS L3VPN FRR supports the following types of backup:
•
VPNv4 route backup for a VPNv4 route.
•
VPNv4 route backup for an IPv4 route.
•
IPv4 route backup for a VPNv4 route.
MPLS backbone
VPNv4_Update: 10.1.0.0/16
RD: 100:1
AS_PATH: 800
EBGP_Update: 10.1.0.0/16
AS_PATH: 100, 100
PE 1 PE 2
CE 3
AS 800
Site 2
EBGP_Update: 10.1.0.0/16
AS_PATH: 800
AS 800
Site 1
AS 100
CE 1
CE 2