[c-nsp] general questions regarding MTU

[Martin T]

If I have a following setup:
http://img203.imageshack.us/img203/4485/mtuj.png ..and I would like to
have connection between "server1" and "server2" over Ethernet v2 using
MTU 9000 bytes. I have few general questions regarding MTU:

1) as I understand, frames larger than MTU are automatically
fragmented by switch. I understand, that it takes some processing
power and probably time as well(latency increases), but are there any
other disadvantages if fragmentation occurs?

2) when we talk about MTU(standard Ethernet v2 frame 1500B, jumbo
frames 1500B - 9000B etc), then we don't count in L2 header? So for
example 802.1qinq frame including multiple VLAN tags, srcMAC, dstMAC,
EtherType and CRC with payload less 1500B is still counted as regular
Ethernet v2 MTU?

3) on the image, all the switches have "system mtu 1552". Am I
correct, that "system mtu" setting only affects 10BASE-T and
100BASE-TX ports? And this 1552B does not include the L2 header,
right?


regards,
martin