Information Technology Reference
In-Depth Information
Figure 7-12
Following the Physical Topology
R1
R2
R1
R2
R1
R2
RR
RR
RR
RR
RR
Client
R3
R4
R5
R3
R4
R5
R3
R4
R5
Clients
Client
Client
Clients
RR
Physical
iBGP
No Physical Link Between RRs
Following Logical Topology
Following Physical Topology
Figure 7-13 is another example of solving a problem by following the physical topology.
Although there are redundant iBGP connections for clients to both RRs, there are no
redundant physical links. If the physical link between R3 and R1 breaks, for example, R3's
iBGP session with R2 also breaks. So the redundant iBGP connections do not really add
any redundancy. One solution is to balance the logical connection with a physical link
between the client and the redundant RR.
Figure 7-13
Physical Topology Balances with the Logical Topology
R1
R2
R1
R2
RR
RR
RR
RR
R3
Client
R4
R3
Client
R4
Client
Client
Physical
iBGP
Logical Connections
Physical and Logical Connections
If the original design is used to allow redundant logical connections in an RR cluster (both
R1 and R2 are in the same cluster), and additional physical links are not an option, the
