R3303-HP HSR6800 Routers MPLS Configuration Guide

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A PE adds the VC label assigned by the peer PE into a Layer 2 packet from a local CE. For example,
when PE 1 forwards packets from CE 1 to CE 2, it adds VC label 3001.
Figure 42 Label distribution in Kompella mode
As shown in Figure 42, CE 1 and CE 2 belong to VPN 1. CE 3 and CE 4 belong to VPN 2. Configure
route targets for the two VPNs to make sure CEs in the same VPN can set up a VC and CEs in different
VPNs cannot.
A VC is set up as follows (take the VC between CE 1 and CE 2 as an example):
1. PE 1 sends the RD, CE ID, route target (export target configured for VPN 1 on PE 1), and the label
block for CE 1 to PE 2 in a BGP update message.
2. When PE 2 receives the update message, it compares the route target in the message against the
import targets locally configured for VPNs. If a match is found, PE 2 learns the L2VPN information
in the update message for the matching VPN. Otherwise, it does not learn the L2VPN information.
In this example, the route target value carried in the update message for CE 1 is 100:1, which
matches the import target of VPN 1 on PE 2. Therefore, PE 2 adds the CE 1 L2VPN information
only to VPN 1 but not to other VPNs.
3. PE 2 sends a BGP update message for CE 2 to PE 1. PE 1 processes the update message as PE 2
does.
4. PE 1 and PE 2 calculate the local and remote VC labels for the VC according to the learned L2VPN
information.
The VC is successfully set up after both PE 1 and PE 2 calculate the VC labels.
Table 2 c
ompares the implementation modes of MPLS L2VPN.