Jumbo Frame Question
- Thread starter smccloud
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as I understand it you need to have a router to connect different frame size networks together. Basically the idea is to make one segment for your Jumbo frame devices, and another segment for your non-jumbo frame devices, and you route between the segments.
The answer to that is complicated. In order to avoid more complicated answers most people recommend tuning every node of the network to the same MTU value (where any MTU > 1500/1514 is generally considered to be jumbo frames).
In reality, if you have a subset of your network nodes communicate using jumo frames and the rest communicate using "standard" MTUs then it will work just fine. You just have to ensure that the switches/routers that make up the transport part of your network support the maximum MTU you are using.
The problems will arise when the machines using jumbo frames try to interact with the machines that do not support jumbo frames. In some cases (most cases, actually) everything will be fine the layer-4+ protocols will just negotiate to the maximum common MTU value. Some things might take a bit longer because of this extra negotiation and some protocols may never reach maximum performance due to the mismatch (for example, TCP congestion controls will take longer to converge onto the best window sizes). But most of the time you wont notice. A few things might not work at all (e.g., UDP based streaming from the "larger" MTU server).
Of course, you also need to examine why you are looking to do jumbo frames at all. In GigE environments using modern NICs (i.e., NIC with protocol offloads) there is little to no advantage to jumbo frames. If you are doing 10Gbe then you might see some gain (though even that is subject to some fair debate).
In reality, if you have a subset of your network nodes communicate using jumo frames and the rest communicate using "standard" MTUs then it will work just fine. You just have to ensure that the switches/routers that make up the transport part of your network support the maximum MTU you are using.
The problems will arise when the machines using jumbo frames try to interact with the machines that do not support jumbo frames. In some cases (most cases, actually) everything will be fine the layer-4+ protocols will just negotiate to the maximum common MTU value. Some things might take a bit longer because of this extra negotiation and some protocols may never reach maximum performance due to the mismatch (for example, TCP congestion controls will take longer to converge onto the best window sizes). But most of the time you wont notice. A few things might not work at all (e.g., UDP based streaming from the "larger" MTU server).
Of course, you also need to examine why you are looking to do jumbo frames at all. In GigE environments using modern NICs (i.e., NIC with protocol offloads) there is little to no advantage to jumbo frames. If you are doing 10Gbe then you might see some gain (though even that is subject to some fair debate).
Well you can certainly enable jumbo frames on the switch itself without affecting anything. Assuming it is a layer-2 switch then it will not be generating any packets and enabling jumbo frames simply permit transit of large packets over the switch.
Then you can experiment with enabling jumbo frames on various server/hosts on your network and see what happens. Be methodical...make a single change on a single node (or perhaps two nodes if you want a meaning test) and see what breaks, test performance, etc. Best way to get experience is hands on.
Then you can experiment with enabling jumbo frames on various server/hosts on your network and see what happens. Be methodical...make a single change on a single node (or perhaps two nodes if you want a meaning test) and see what breaks, test performance, etc. Best way to get experience is hands on.
Heres a good guide on how you can test jumbo frames on your equipment.
How to test if 9000 MTU/Jumbo Frames are working - Myles Gray
for example,
How to test if 9000 MTU/Jumbo Frames are working - Myles Gray
for example,
Code:
Windows
ping -f -l 8958 IP_of_another_machine
OmniOS/Solaris
ping -s IP_of_another_machine 9000 4