How Mce Works; Routing Information Exchange For Mce; Route Exchange Between A Ce And The Private Network - 3Com S7906E Configuration Manual

An S7900E switch with MCE enabled can solve this problem. By binding the VLAN interfaces to the
VPNs in a network on an S7900E switch of this kind, you can create and maintain a routing table for
each of the VPNs. In this way, packets of different VPNs in the private network can be isolated.
Moreover, with the cooperation of the PE, the routes of each VPN can be advertised to the
corresponding remote PE properly, so that packets of each VPN in the private network can be
transmitted securely through the public network.

How MCE Works

Figure 1-3 illustrates how MCE creates and maintains routing entries of multiple VPNs and how the
MCE exchanges VPN routes with PEs.
Figure 1-3 How MCE works
In Figure 1-3, the two VPN sites on the left side (Site 1 and Site 2) are connected to the backbone
network through an MCE device. Two VPN tunnels are expected between them and the remote VPNs
at Site 2 and Site 1.
With MCE enabled, routing tables can be created for VPN 1 and VPN 2 individually, VLAN-interface 2
can be bound to VPN 1, and VLAN-interface 3 can be bound to VPN 2. When receiving a piece of
routing information, MCE determines the source of the routing information according to the number of
the interface receiving the information and then maintains the corresponding routing table accordingly.
You need to also to bind the interfaces to the VPNs on PE 1 in the same way as those on the MCE
device. The MCE device is connected to PE 1 through a trunk, which permits packets of VLAN 2 and
VLAN 3 with VLAN tags carried. In this way, PE 1 can determine the VPN a received packet belongs to
according to the VLAN tag of the packet and passes the packet to the corresponding tunnel.

Routing Information Exchange for MCE

Interface-to-VPN-instance binding enables CEs and PEs to determine the sources of received packets
and then forward the packets according to the routing information concerning the corresponding VPNs.
The following sections describe the way how MCE transmits the private routing information of multiple
VPNs to PEs properly.

Route Exchange between a CE and the Private Network

A CE can adopt the following routing protocols to exchange VPN routes with a site:
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