H3C Technologies H3C S10500 Series Switches - Manual (Page 18)

7
• iBGP
• eBGP
NOTE:
This briefly introduces the cooperation of routing protocols and MCE. For information about the routing
protocols, see
Layer 3—IP Routing Configuration Guide.
Static routes
An MCE can communicate with a site through static routes. As static routes configured for traditional CEs
take effect globally, address overlapping between multiple VPNs remains a problem until the emergence
of MCE. MCE allows static-route-to-VPN-instance binding, which isolates the static routes of different
VPNs.
RIP
The switch can bind RIP processes to VPN instances. With these bindings on the MCE, private network
routes of different VPNs can be exchanged between MCE and sites through different RIP processes,
isolating and securing VPN routes.
OSPF
The switch can bind OSPF processes to VPN instances and isolate the routes of different VPNs.
For an OSPF process bound to a VPN instance, the router ID of the public network configured in system
view is invalid. You must specify the router ID when creating an OSPF process.
An OSPF process can be bound to only one VPN instance; however, a VPN instance can use multiple
OSPF processes for private network route transmission. To ensure routes can be advertised properly,
configure the same domain ID for all the OSPF processes bound to a VPN instance.
NOTE:
When an OSPF route is imported to the BGP routing table as a BGP route on a PE, some attributes of the
OSPF route get lost. When the BGP route is imported to the OSPF routing table on the remote CE, not all
the attributes of the original OSPF routes can be restored. As a result, the route cannot be distinguished
from the routes imported from other domains. To distinguish OSPF routes imported from different OSPF
domains, the OSPF routes to be imported to the BGP routing tables on PEs must carry an attribute (the
OSPF domain ID) to identify the OSPF domains. The domain ID of an OSPF process is contained in the
routes generated by the process. When an OSPF route is imported to BGP, the domain ID is added to BGP
VPN routes as the extended BGP community.
In cases where a VPN has multiple MCE devices attached to it and when an MCE device advertises the
routes learned from BGP within the VPN, the routes may be learned by other MCE devices, generating
route loops. To prevent route loops, configure route tags for different VPN instances on each MCE. H3C
recommends that you assign the same route tag to the same VPN on all MCEs.
IS-IS
Similar to those in OSPF, IS-IS processes can be bound to VPN instances for private network routes to be
exchanged between MCE and sites. An IS-IS process can be bound to only one VPN instance.
iBGP
To use iBGP to exchange private routes between an MCE and a site, configure iBGP peers for VPN
instances on the MCE and redistribute IGP routing information from corresponding VPNs. If the MCE is
connected with multiple sites in the same VPN, you can configure the MCE as a route reflector (RR) and