By this time, if you're either a vendor, or a consumer of network equipment, you're probably asking yourself one of the following questions :
- Why haven't I started buying/manufacturing equipment that supports large MTUs ?
- Are they assuming I'm too ignorant to be aware of the cost of such modifications ?
In both cases your question would be perfectly legit. This is why we've gathered a list of Pros and Cons, to help you establish your opinion on this subject.
PROs
- Significantly reduces CPU utilization on hosts (see Demonstration)
- Significantly reduces network overhead (see Demonstration)
- Improves TCP performance, and optimizes window size utilization (see TCP Performance)
- Reduces fragmentation and MTU misalignment problems for hosts connected to private large MTU networks
CONs
- Path MTU Discovery doesn't work (Can be fixed) - This causes most hosts to use default low MTUs.
- The Ethernet CRC limits packets to about 12 kBytes - In order to achieve the same error detection rate. However, as all standards, Ethernet can also be modified.
- Larger packets will cause too much jitter - Relevant for jitter sensitive applications like voice and video. Let's not forget that certain segments can still be privately limited.
- Very Expensive - Requires many expensive hardware replacements throughout the Internet.
- Not enough people want larger MTU to justify the expense (For many, today's performance is perfectly adequate).
- "If it ain't broke don't fix it" (People are afraid of replacing a good system).
