Carsten Grohmann
changed
bug 11861
| What |
Removed |
Added |
| Status |
RESOLVED
|
UNCONFIRMED
|
| Resolution |
NOTABUG
|
---
|
Comment # 6
on bug 11861
from Carsten Grohmann
I really won't be impolite, but I still think this is an bug.
Let me explain why:
RFC2474 describes the structure of the DS field:
The DS field structure is presented below:
0 1 2 3 4 5 6 7
+---+---+---+---+---+---+---+---+
| DSCP | CU |
+---+---+---+---+---+---+---+---+
DSCP: differentiated services codepoint
CU: currently unused
In a DSCP value notation 'xxxxxx' (where 'x' may equal '0' or '1')
used in this document, the left-most bit signifies bit 0 of the DS
field (as shown above), and the right-most bit signifies bit 5.
This means the bits 0 to 5 are used for DSCP. The upper two bits 6 and 7 are
used to ECN.
The Wireshark dissection shows the lowest bit on the right side - that's
opposite to the RFC which shows the lowest bit on the left side.
Based on this I think the discussed and shown dissection is WRONG:
Differentiated Services Field: 0x08 (DSCP: Unknown, ECN: Not-ECT)
0000 10.. = Differentiated Services Codepoint: Unknown (2)
.... ..00 = Explicit Congestion Notification: Not ECN-Capable Transport
(0)
I would expect a dissection like:
..00 1000 = Differentiated Services Codepoint: CS1 (8)
00.. .... = Explicit Congestion Notification: Not ECN-Capable Transport
(0)
Please excuse if I'm wrong in this.
Regards,
Carsten
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