This is done intentionally to conserve the CPU and bandwidth requirements. Extensive operational experience with BGP in the Internet showed that indeed the use of the incremental updates allows significant saving both in terms of the CPU utilization and bandwidth consumption. However, to operate correctly the incremental updates must be exchanged over a reliable Page 6 transport. BGP uses TCP as such transport. Extensive operational experience with BGP in the Internet showed that the only real problem that was attributed to BGP in general, and the use of TCP as the transport for BGP in particular, was its slow convergence in presence of congestion.
All links are heavily utilized and are often congested.
This is because a large percentage of packets carrying BGP information are being dropped due to congestion. Observe, that any transport protocol used by BGP would have difficulty preventing packets from being dropped under congestion, since it has no direct control over the routers that drop the packets, and the congestion has nothing to do with the BGP traffic. If packets carrying routing information are lost, any distributed routing protocol will exhibit slow convergence. If quick convergence is viewed as important for a routing within a network, special measures to minimize the loss of packets that carry routing information must be taken. The next section suggests some possible methods.