イーサネットのフレームサイズ

質問

すみません。素人です。
イーサネットのフレームサイズは最大1500bytesだと思います。
キャプチャしているとサイズが1820bytesのフレームがあります。
これはMTUが自動調整？された為なのでしょうか？

No. Time Source Destination Protocol Length Info
824 14:44:01.923131000 192.168.3.66 192.168.3.63 TDS 1820 SQL batch

Frame 824: 1820 bytes on wire (14560 bits), 1820 bytes captured (14560 bits) on interface 0
Interface id: 0 (\Device\NPF_{ECF8F6F2-31BA-4ECF-9C24-209B41990ECE})
Encapsulation type: Ethernet (1)
Arrival Time: Jul 13, 2015 14:44:01.923131000 譚ア莠ャ (讓呎コ匁凾)
[Time shift for this packet: 0.000000000 seconds]
Epoch Time: 1436766241.923131000 seconds
[Time delta from previous captured frame: 0.001591000 seconds]
[Time delta from previous displayed frame: 0.001591000 seconds]
[Time since reference or first frame: 23.520874000 seconds]
Frame Number: 824
Frame Length: 1820 bytes (14560 bits)
Capture Length: 1820 bytes (14560 bits)
[Frame is marked: False]
[Frame is ignored: False]
[Protocols in frame: eth:ethertype:ip:tcp:tds]
[Coloring Rule Name: TCP]
[Coloring Rule String: tcp]
Ethernet II, Src: WistronI_8c:90:96 (f8:0f:41:8c:90:**), Dst: FujitsuT_ec:2f:66 (00:19:99:ec:2f:**)
Destination: FujitsuT_ec:2f:66 (00:19:99:ec:2f:**)
Address: FujitsuT_ec:2f:66 (00:19:99:ec:2f:**)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Source: WistronI_8c:90:96 (f8:0f:41:8c:90:**)
Address: WistronI_8c:90:96 (f8:0f:41:8c:90:**)
.... ..0. .... .... .... .... = LG bit: Globally unique address (factory default)
.... ...0 .... .... .... .... = IG bit: Individual address (unicast)
Type: IP (0x0800)

回答No.1

t_ohta

ジャンボフレームが有効になっている環境ならデータ長は1500bytesを超える場合があります。