Enabling bgp and igp route synchronization – H3C Technologies H3C S12500 Series Switches User Manual
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Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter BGP view or BGP-VPN
instance view.
•
Enter BGP view:
bgp as-number
•
Enter BGP-VPN instance view:
a.
bgp as-number
b.
ipv4-family vpn-instance
vpn-instance-name
Use either method.
3.
Configure BGP route
reception filtering policies.
•
Filter incoming routes from all
peers with an ACL or IP prefix list:
filter-policy { acl-number |
ip-prefix ip-prefix-name } import
•
Reference a routing policy to
filter routing information from a
peer or peer group:
peer { group-name | ip-address }
route-policy route-policy-name
import
•
Reference an ACL to filter routing
information from a peer or peer
group:
peer { group-name | ip-address }
filter-policy acl-number import
•
Reference an AS path list to filter
routing information from a peer
or peer group:
peer { group-name | ip-address }
as-path-acl as-path-acl-number
import
•
Reference an IP prefix list to filter
routing information from a peer
or peer group:
peer { group-name | ip-address }
ip-prefix ip-prefix-name import
Configure at least one method.
By default, no route reception
filtering is configured.
Enabling BGP and IGP route synchronization
Enable BGP and IGP route synchronization in an AS to avoid giving wrong directions to routers.
By default, upon receiving an IBGP route, a BGP router checks the route's next hop. If the next hop is
reachable, the BGP router advertises the route to EBGP peers. If a non-BGP router works in an AS, it can
discard a packet due to an unreachable destination. As shown in
, Router E has learned a route
of 8.0.0.0/8 from Router D through BGP. Router E then sends a packet to 8.0.0.0/8 through Router D,
which finds from its routing table that Router B is the next hop (configured using the peer next-hop-local
command). Because Router D has learned the route to Router B through IGP, Router D forwards the
packet to Router C through route recursion. Router C does not know the route 8.0.0.0/8, so it discards
the packet.