WAN data packet size

Large data packets may result in added delay for VoIP packets across WAN links with limited bandwidth. Smaller VoIP packets may be held in queue while larger data packets are processed onto a WAN link.

To avoid excessive delay, there may be benefit to fragmenting the larger data packets and interleaving them with the smaller voice packets.

• One technique is to adjust packet size by altering the Maximum Transmission Unit (MTU) size. Minimum MTU size should be no smaller than 300 bytes and no larger than 550 bytes. LAN based MTUs can be as large as 1500 bytes. However, reducing the size of the MTU will add overhead and reduce the efficiency of data applications.
• Other techniques, such as Multilink PPP (MPP) Link Fragmenting and Interleaving (LFI), and Frame Relay Fragmentation (FRF12) allow network managers to fragment larger packets and permit queuing mechanisms to speed the delivery of Real Time Protocol (RTP) traffic without significantly increasing protocol overhead or reducing data efficiency.

Header compression protocols like CRTP (Compressed Real Time Protocol) can and should be used between WAN links.