F3215-HP Load Balancing Module Network Management Configuration Guide-6PW101

266
Ste
p
Command Remarks
3. Configure BGP route
reception filtering policies.
• Reference an ACL or IP prefix list to
filter incoming routes from all peers :
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 ACL 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
Use at least one approach.
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 Figure 158, R
ou
ter 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.
Figure 158 BGP and IGP synchronization in an AS