H3C Technologies H3C S10500 Series Switches - Manual (Page 19)

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configure the egress routers of the sites as clients, making the MCE reflect routing information between
the sites. This eliminates the necessity for BGP connections between sites, reducing the number of BGP
connections and simplifying network configuration.
eBGP
To use eBGP to exchange private routes between an MCE and a site, configure BGP peers for VPN
instances on MCE and redistribute IGP routing information from corresponding VPNs. Sites reside in
different ASs, and eBGP is used for route exchange. In this case, the following configurations are
needed.
1. Use eBGP to import IGP routes from each site
To advertise private network routes to PEs properly, IGP routes in the sites directly connected to an MCE
device must be first imported to the BGP routing table of the MCE device.
2. Configuring a peer group for each VPN instance
For proper route exchange between a CE and a site, configure a peer group for each VPN instance and
assign AS numbers for these peer groups in BGP IPv4 address family view.
3. Applying filtering policies for route filtering
To ensure that routing information is exchanged between sites and PE devices properly, filtering policies
are applied to filter routes received or to be advertised.
Route exchange between an MCE and a PE
Routing information entries are bound to specific VPN instances on an MCE device, and packets of each
VPN instance are forwarded between MCE and PE according to interface. As a result, VPN routing
information can be transmitted by performing relatively simple configurations between MCE and PE,
such as importing the VPN routing entries on MCE devices to the routing table of the routing protocol
running between MCE and PEs.
The following routing protocols can be used between MCE and PE devices for routing formation
exchange:
• Static route
• RIP
• OSPF
• IS-IS
• iBGP
• eBGP
For information about routing protocol configuration and route import, see Layer 3—IP Routing
Configuration Guide.
Configuring an MCE
Configuring VPN instances
Configuring VPN instances is required in all MCE networking schemes.
By configuring VPN instances on a PE, you isolate not only VPN routes from public network routes, but
also routes of a VPN from those of another VPN. This feature allows VPN instances to be used in
networking scenarios besides MCE.