James Carlson wrote:
[EMAIL PROTECTED] writes:
The mtu reported here is the same as that reported in 'ifconfig -a',
i.e., the link-layer mtu.
"ifconfig -a" reports the network layer MTU, not the link layer MTU
because (to repeat what everyone else says), ifconfig on Solaris
shows IP network interfaces, not anything else.
Correct.
I can shove 1536 bytes of garbage in a normal ethernet frame.
I can shove 1500 bytes of garbage in a normal IP packet.
The first number isn't really defined anywhere. The actual number
(from IEEE 802.3-2002 section 4.4.2) is 1518 for the
maxUntaggedFrameSize, which is the payload plus the 14+4 Ethernet
overhead, meaning 1500 octets total available for network layers. Per
IEEE, the tag is separate from this number.
...
In any event, I don't think MTU is at all ambiguous here. It's the IP
MTU which happens to be equal to the maximum MAC client SDU on
Ethernet. (Well, it needs to be _less_ or equal, but it's almost
always equal.)
Ok, well, it seems a little odd to me that we report an IP thing
amongst a collection of link layer properties. In that case, does
it even belong here? Why not also present the TCP MSS too?
A problem I can see is that ifconfig has no way of telling you,
in this case, what the maximum MTU is for a link, so dladm
is useful for that...but...I'm still not sure this makes sense.
This seems like a layer violation...
Darren
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