Information Technology Reference
In-Depth Information
OSPF 50
EIGRP 100
140.1.0.0
170.10.0.0
170.10.8.1/30
140.1.9.1/24
S0
E0
Router B
Figure 11-22
OSPF and EIGRP Redistribution
Another redistribution point where filtering is important is in a multihomed BGP connec-
tion with multiple Internet providers. When BGP routes get exchanged with multiple In-
ternet service providers (ISP) route filtering is used to prevent of advertisement of private
addresses and addresses that are out of scope of the domain. Route filtering is also used
to filter routes at the redistribution of BGP into IGPs such as OSPF, EIGRP, or RIP.
Routing Protocols on the Hierarchical Network Infrastructure
The selected routing protocol should be used based on the network design goals and the
network module being used. As shown in Figure 11-23, high-speed routing is recom-
mended for the network core and distribution layers. These routing protocols react fast to
network changes. It is a best practice that the same routing protocol be used in the three
layers (core, distribution, access) of the enterprise network.
The enterprise edge connects the campus network with external connectivity including
WA N , I n t e r n e t , V P N , r e m o t e - a c c e s s m o d u l e s . R o u t i n g p r o t o c o l s i n t h e e n t e r p r i s e e d g e
may be EIGRP, OSPF, BGP, and static routes. Specifically in the Internet module you will
find BGP/static routes.
Ta ble 1 1- 9 shows a summary of the recommended routing protocols in the network infra-
structure.
Ta b l e 1 1- 9
Routing Protocols on the Hierarchical
Network Infrastructure
Network Module
Routing Protocols
Campus core
EIGRP, OSPF
Campus distribution
EIGRP, OSPF
Enterprise edge
EIGRP, OSPF, BGP, Static
Internet and VPN modules
BGP, Static
