Traffic engineering
226 Avaya Application Solutions IP Telephony Deployment Guide
Of the flow components listed above, the first three, related to call traffic, should be the most
commonly considered loads. Call traffic patterns and profiles heavily depend on the specific
type of business conducted at the branches, such as retail, support, marketing, insurance, real
estate. However, we generally expect a large portion of the branch call traffic to be confined to
the branch — that is, call signaling handled entirely within the branch without routing through
SES edge. These intra-branch calls include local PSTN calls at the branch location over analog,
BRI, or T1 connections to the local central office. Only a smaller fraction (10-20%) should route
outside the branch through the SES edge. This is why a single SES edge server can support
1000 branches and 40,000 stations.
Instant messaging and presence subscriptions are relatively new forms of traffic load and their
use depends on user adoption. Therefore, traffic loads for these services are currently difficult to
predict. Presence subscription, in particular, scales as the product of presence users and
subscribers, and has potential to scale as the square of the user population, quickly becoming
the dominant load.
Avaya has developed detailed traffic flow models to estimate the load on an SES edge based
on the analysis described above. With these tools, we can ensure proper deployments based
on individual customer needs.
