MPLS virtual private network OptionB experiment (Huawei equipment)

Experimental topology:

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Step 1: Configure the IP address (note that there is no need to create VPN instances between ASBRs, and the RT values of the two PE instances need to be the same) On
PE1: On

PE2:

Step 2: The establishment of the IGP neighbor relationship in the area, MPLS Configuration (omitted, it should be noted that the interface between the two ASBRs needs to be configured with MPLS, but MPLS LDP does not need to be enabled).

Step 3: Configure BGP peers (take PE1, CE1, and ASBR1 as examples).
CE1:
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PE1:

ASBR: Be careful to disable VPN-Target detection and enable the use of the next hop for label allocation.

Traffic analysis: CE1pingCE2:

CE1 sends a packet (destination address 8.8.8.8/32) to PE1, uses the RD value to find the corresponding VRF, unpacks the corresponding FIB table, encapsulates the inner label 1026, and knows that the tunnel ID is 0x3:
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So check the LFIB Table:

Check the next hop information, encapsulate 1025 as the outer label, and send it from the outgoing interface G0/0/1.

After P1 receives it, check the LFIB table: the outgoing label is hidden label 3, so the outer label is stripped and sent out from the g0/0/1 interface.
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After ASBR1 receives it, it checks the LFIB table, because only the inner label is matched to the incoming label 1027, and the outgoing label is switched to 1027.

Detailed information:

Although there is no outgoing interface in this table, the relay token can be found through the BGP Key corresponding to the relay tunnel out-interface. Use the command dis bgp vpnv4 all routing-table 8.8.8.8 (destination address) to find it. The outgoing interface here is g0/0/1, which is sent to ASBR2.

After the ASBR receives it, check the LFIB table:
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exchange the labels, check the detailed information:

find the outer encapsulated label 1024 according to the outgoing token 0x4 corresponding to the token, and send it to P2: After

P2 receives it, check the LFIB table: found out The label is 3 (implicit label), and the outgoing interface is g0/0/0.
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The outer label is stripped and sent. After receiving it, PE2 finds that there is only the inner 1026 label, and the out label is NULL:

so the stripped label is sent from the vrf forwarding table of to65002 to CE1 to complete the data transmission.