On 28/03/2007, at 3:01 PM, Ian Batterbee wrote:
Has anyone got any real world experience of the usefulness of jumbo frames on ethernet (ie, MTU > 1500 bytes). A number of 1000mbps interfaces support it, but it seems to be that it would only be useful if jumbo frames were supported and enabled on all equipment between the sending NIC and final IP destination, so I'm struggling to see how enabling it in just say the core of a network would be all that helpful.
Well if you're after increased TCP session throughput, jumbo frames are nowhere near as might seem (refer to Perry's TCP bandwidth calculator), and in this case end to end large MTU support is required. If you're running any form of encapsulation in your network, then being able to encapsulate complete 1500 byte frames is indeed a useful feature. Usually in this case though, you're simply after something 'a bit bigger' than 1500 bytes. In either case, there is no reason _not_ to enable support for the largest MTU you can support wherever possible. No point in waiting for the entire inter-network to support them otherwise it'll never happen :). Cheers, Jonny.