Information Technology Reference
In-Depth Information
Figure 5-18
Network Topology for Remote Site Aggregation
EIGRP 102
BGP 65102
R5
R7
R1
R6
R4
EIGRP 103
BGP 65103
EIGRP 100
BGP 65100
R8
EIGRP 101
R10
BGP 65101
R3
R9
R2
R11
R14
EIGRP 105
BGP 65105
R13
EIGRP 105
BGP 65105
Frame Relay
Cloud
Remote Sites
EIGRP 105
In the examples so far, for the sake of clarity, each region has been summarized into a single
prefix. However, there is no requirement that the prefixes in a region must be summarized
before being injected into BGP. In the previous example, with a single prefix, it is very easy
to perform the prefix filtering using a prefix list. If there were a large number of prefixes, it
is possible that using a filter list to block prefix advertisements based on AS would be more
appropriate. Previous architectures required packet filtering, which is more resource-
intensive and tends to have higher administrative complexity because of the access control
list semantics.
