This is our old Q&A Site. Please post any new questions and answers at

for some traces DHCP discovery packets, DHCP option 60 VCI value is EMPTY but in hex area we can see values in Bytes and HEX ... with length 7

Why VCI area is shown empty???

Option 60 length 7 Vendor Class identifier= "empty"

in bytes option code = 3c length = 07 value = 00 00 22 03 48 47 57

asked 05 Mar '15, 05:20

Junaid's gravatar image

accept rate: 0%

What is your OS and which version and what is your Wireshark version? Can you share a capture in a publicly accessible spot, e.g. CloudShark?

(05 Mar '15, 08:21) Jaap ♦

Maybe because the actual value begins with zeroes, which could indicate a string terminator - so the Wireshark dissector probably thinks that the string is finished at the first byte. I'm just guessing though.

permanent link

answered 05 Mar '15, 05:49

Jasper's gravatar image

Jasper ♦♦
accept rate: 18%

may be, issue is actually; my BRAS is also no relaying this to DHCP Is it possible, BRAS is considering it a NULL value also and dropping the packet!??

(05 Mar '15, 06:25) Junaid

RFC 2132 just says the value is a "string of n octets"; it doesn't say "character string", as it does for some other options. The Wireshark dissector currently treats it as a character string; you might need to check with the supplier of whatever hardware/software is sending that packet to find out how that field is to be interpreted.

permanent link

answered 05 Mar '15, 17:48

Guy%20Harris's gravatar image

Guy Harris ♦♦
accept rate: 19%

Your answer
toggle preview

Follow this question

By Email:

Once you sign in you will be able to subscribe for any updates here



Answers and Comments

Markdown Basics

  • *italic* or _italic_
  • **bold** or __bold__
  • link:[text]( "title")
  • image?![alt text](/path/img.jpg "title")
  • numbered list: 1. Foo 2. Bar
  • to add a line break simply add two spaces to where you would like the new line to be.
  • basic HTML tags are also supported

Question tags:


question asked: 05 Mar '15, 05:20

question was seen: 2,598 times

last updated: 05 Mar '15, 17:48

p​o​w​e​r​e​d by O​S​Q​A