TMS zl Management and Configuration Guide ST.1.0.090213

9-12
Routing
Dynamic Routing
On the other hand, routing protocols consume bandwidth as routers exchange
updates and CPU processes as routers calculate the best routes. In addition,
a router that has been carelessly configured may send updates to unauthorized
devices, creating a security vulnerability. However, a well-designed network
eliminates many of these problems.
Table 9-3 lists some advantages and disadvantages of RIP and OSPF. As you
can see, each protocol provides different best uses. Keep in mind that proto-
cols work in conjunction with each other.
Table 9-3. Advantages and Disadvantages of RIP and OSPF
The administrative distance for a protocol indicates how reliable the router
considers routes discovered by that protocol to be. The lower the administra-
tive distance, the more trusted the route. Table 9-4 shows the default admin-
istrative distance for the various types of routes that the TMS zl Module can
learn.
Table 9-4. Hierarchy of Routes
Protocol Advantages Disadvantages Uses
RIP • Configuration is simple.
• RIP v2 can communicate with
an external network.
• Convergence is relatively slow.
• Metric is based only on hop
count.
• If used to connect to an ISP, the
ISP must redistribute the
routes into BGP.
•LANs
• Simple WANs
• Connecting to an external
network
• Not used over dial-up
connections
OSPF • Accurate routes take link
speed and cost into account.
• Convergence is fast.
• Overhead is as low as RIP if the
network is well-designed.
• Configuration is complicated.
• Overhead can be high.
• OSPF cannot be used as an
EGP without redistribution.
• More extensive LANs and
WANs
• Not used over dial-up
connections
Type of Route Default Administrative Distance
Directly connected 0
Static 1
OSPF 110
RIP v1 and v2 120