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The NE40E Cannot Advertise the BGP Private Aggregation Route Due to the BGP Routing Feature of Huawei

Publication Date:  2012-07-27 Views:  95 Downloads:  0

Issue Description

The networking diagram is as follows:
NE40E version: V3R1C01B05D (the version of the NE40E does not matter in this case)
The private network BGP VPNV4 Peer is set up between the NE40Es. NE40E-1 uses the MP-BGP to advertise the private route to NE40E-2. Initiate a routing policy so that NE40E-2 can only receive the private aggregation route with the mask of 23 bits.
The configuration of NE40E-1 is as follows:
ipv4-family vpn-instance CT_SoftSwitch_Media
peer as-number 4809
peer advertise-community
aggregate detail-suppressed
import-route direct
Result: NE40E-2 fails to receive the private aggregation route sent by NE40E1. 

Alarm Information


Handling Process

1. Because the aggregate method is adopted, there must be a more specific selected aggregation route. Check whether the detailed route exists.
2. Check whether the private aggregation route is preferentially selected on NE40E-1.
display bgp vpnv4 vpn-instance CT_SoftSwitch_Media routing-table
* 0 ?
The private aggregation route is not selected, and thus the route cannot be sent to the peer device.
3. Based on the BGP routing rule on the Huawei VRP, check the routing table of the entire network. It is found that there is a static route with null0 as the next hop. The default precedence of the static route is 60. The relevant configuration is as follows:
ip route-static vpn-instance CT_SoftSwitch_Media NULL0
Delete this route, and the fault is fixed. 

Root Cause

The BGP routing rule on Huawei VRP is different from that of the competitor C. In Huawei, before the BGP routing process is conducted, the route precedence of different protocols on the entire network is compared. If among the routes on the entire network, there is a route and the precedence of the route is less than BGP (255 by default), the route is not preferentially selected in BGP. The device of C only compares the BGP routing table. 


Regardless the public network or the private network, BGP advertises aggregation routes in two ways:
1. The aggregate method is adopted (this case).
2. The network and the static null0 route are adopted (recommended). The configuration in this case can also be:
ip route-static vpn-instance CT_SoftSwitch_Media NULL0
ipv4-family vpn-instance CT_SoftSwitch_Media
peer as-number 4809
peer advertise-community
import-route direct