It was a long time getting here, but you have arrived, and you are now ready to rush headlong into a Junos software-based CoS configuration and verification lab. Figure 10-16 provides the network topology for the IP DiffServ CoS deployment scenario.
Figure 10-16. DiffServ CoS deployment topology
There are a few things to note in Figure 10-16. The test topology is somewhat simplified, and the test bed lacks the external test equipment needed to accurately measure and verify data plane performance. The first issue is not really a problem, because a workable CoS configuration is somewhat repetitive, basically involving the need to put the same configuration bits, consistently, in lots of places. As such, any network with a clearly marked edge and distribution/core devices services is a workable model with which to demonstrate CoS configuration and operational verification.
The subset of routers selected for the CoS topology was chosen in
large part because of the (relatively) low-speed T1 interface
Porter. We noted previously that CoS matters only when link utilization begins to approach 80%. Obviously, with a given offered load, a slower link will exhibit higher utilization than a faster one—considering the lack of external traffic generators, it will be hard enough to congest a T1 link, let alone a 1 Gbps Ethernet. In fact, ...