Information Technology Reference
In-Depth Information
In AS 65101, both R1 and R2 receive a path for the prefix 10.2.0.0/16 from R3. Figure 5-14
shows the topology for the DMZ between AS 65101 and AS 65100. R1 and R2 each install
the path they learned via eBGP from R3 and advertise that path via iBGP to each other. The
path-selection process should result in the final path selection on R1 and R2 being the exter-
nally learned path. This path is chosen based on the internal versus external step in the deci-
sion algorithm, with the assumption that no eBGP policies are applied.
Figure 5-14
Detailed DMZ Between AS 65100 and AS 65101
RID - 172.16.13.1
E0 - 172.17.1.1/24
R1
BGP 65101
BGP 65100
Prefix Advertised
10.2.0.0/16
R3
R2
RID - 172.16.3.1
E0 - 172.17.1.254/24
RID - 172.16.2.1
E0 - 172.17.1.2/24
AS 65103 has a slightly different scenario. Figure 5-15 shows the topology for the DMZ
between AS 65103 and AS 65100. R10 receives two paths, which appear to be identical
from R8 and R9. The only difference is the router ID. This results in R10 basing its path
selection on the lowest router ID and selecting either R8 or R9.
Figure 5-15
Detailed DMZ Between AS 65100 and AS 65103
RID - 172.16.8.1
E0 - 172.17.3.253/24
R8
BGP 65100
Prefix Advertised
10.2.0.0/16
BGP 65103
R10
R9
RID - 172.16.10.1
E0 - 172.17.3.1/24
RID - 172.16.9.1
E0 - 172.17.3.253/24
