An Investigation into Transport Protocols and Data Transport ...

6.2. Discussion and Deployment Considerations of New-TCP Algorithms131
amount of buffering increases substantially. Fortunately, [AKM04] also states
that due to the lack of synchronisation between competing flows, the queue
size provision (for Standard TCP flows) requirement is related to the inverse
square root of the number of flows.
Another method to reduce synchronisation is to implement RED on the
bottleneck queue to cause non-synchronised drops from competing flows. It
also has the benefit of being able to actively prevent congestion by the dropping
of packets before a potential buffer overflow and therefore the ability
to maintain smaller sized buffers and provide lower-delay interactive services
[BCC98].
6.2.3 Interaction with Legacy and other Traffic
As phased deployment of any Internet protocol is likely, New-TCP algorithms
should be able to coexist fairly with Standard TCP flows. Whilst the investigation
of interaction with legacy traffic is more suited to a discussion of the
self-similar nature of TCP aggregate flows [LTWW94, PKC97], the interaction
between the bulk transport of data using Standard TCP and New-TCP
algorithms should be studied.
This co-existence with other traffic is considered trivially by nearly all
of the algorithms by simply defining a threshold at which the New-TCP
algorithms will switch from their low-speed modes to their high speed modes.
This is implemented by defining an arbitrary value of cwnd such that they
mimic the standard AIMD algorithm below this value. This ensures that the
algorithms can co-exist with Standard TCP under low cwnd environments,
yet are able to achieve high throughput on high-BDP paths.
H-TCP, however, proposes a radically different way of determining how