In this case computer or service with limited bandwidth can not exceed assigned limit. Bandwidth limitation is possible to set by header fields of protocols: Ethernet, IP, TCP, UDP, ICMP.
DoS attack protection secures against SYN flood or connect flood attack and TCP protocol inspection drops harmful TCP packets. In firewall can be set prohibiting of opening TCP connection from chosen side. These functions can protect corporate network connected to internet and secures chosen opened ports on gateway used for connecting from internet to corporate network. Packet filter can work with protocols : Ethernet, IP v4, TCP, UDP, ICMP.
You can monitor and log bandwidth utilization for some computer or group of computers or for some network service. Bandwidth Management and Firewall has counters which allows monitoring of current data flow and sum of transferred data for some computer or network service. The results can be used for efficient using of bandwidth leased from your ISP and for detection of bandwidth lack.