43.1 Network Setup

The implementation of Tmix in ns-2 is based on PackMime-HTTP (Chapter 42), so it has a similar structure. A typical Tmix instance consists of four ns nodes: two initiator nodes and two acceptor nodes (Figure 43.1).

Figure 43.1: Tmix Architecture. Each Tmix object controls an initiator cloud and an acceptor cloud. Each cloud can represent multiple initiator or acceptor Applications. For realistic two-way traffic, two sets of acceptors and initiators are required.

It is important to note that these nodes do not correspond to a single initiator or acceptor. A single Tmix initiator node generates TCP connections coming from a ``cloud'' of connection initiators. Likewise, a single Tmix acceptor node accepts and serves TCP connections destined for a ``cloud'' of connection acceptors.

In order to simulate different RTTs, bottleneck links, and/or loss rates for each connection, Tmix should be used in conjunction with Tmix_DelayBox (see Section 43.4), derived from DelayBox (Chapter 22).

We use the terms inbound and outbound to represent the directions of data flow. As in Figure 43.1, traffic initiated outside of the circle (which could be thought of as a campus) is designated as inbound, and traffic initiated inside the circle is designated as outbound.