Operation Manual – MCE
H3C S3610&S5510 Series Ethernet Switches
Chapter 1 MCE Overview
1-8
Note:
Normally, 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. In order 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) used 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 have multiple MCE devices attached to it, when a MCE device
advertises the routes learned from BGP within the VPN, the routes may be learned by
other MCE devices, thus generating route loops. To prevent route loops, you can
configure route tags for different VPN instances on each MCE. It is recommended that
a VPN be assigned the same route tag on multiple MCEs.
IV. IS-IS
Similar to those in OSPF, IS-IS processes can be bound to VPN instances for private
network routes to be exchanged between CEs and sites. An IS-IS process can be
bound to only one VPN instance.
V. EBGP
To use EBGP to exchange private routes between a CE and a site, you need to
configure BGP peers for VPN instances on CEs and import IGP routing information
from corresponding VPNs. Normally, sites reside in different ASs, so EBGP is used for
route exchange. In this case, the following configurations are needed.
1)
Configuring to 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 need to 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, you need to 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 make sure that routing information is exchanged between sites and PE devices
properly, filtering policies are applied to filter routes received or to be advertised.
