VTP messages

[engebied1]

Hello, guys

I could really use your help , as you see in the question above found in the CCNA cisco material one of the two true answers that the configuration revision number is in all types of VTP messages , but as i studied that the VTP request advertisments fields does not have it , can some one please explain ?

thank.

[Rolf Fischer]

Hi Mohammed,

following events make a switch request VTP information:

• The switch has been reset.
• The VTP domain name has been changed.
• The switch has received a VTP summary advertisement with a higher configuration revision than its own.

So in that cases the own configuration revision number (Zero or lower than the crn of the domain) is not important for the rest of the VTP domain.

You can find the frame formats and additional information here:

http://www.javvin.com/protocolVTP.html

http://www.cisco.com/en/US/tech/tk389/tk689/technologies_tech_note09186a0080094c52.shtml

Hope that helps

Rolf

[Renan Abreu]

Just to complement Rolf`s answer, this is the debug of a switch that has no config (has been reset).

*Jul 22 15:03:55.623: VTP LOG RUNTIME: Summary packet received in NULL domain state

*Jul 22 15:03:55.623: VTP LOG RUNTIME: Summary packet received, domain = CISCO, rev = 878, followers = 0, length 77, trunk Et1/1

*Jul 22 15:03:55.623:

*Jul 22 15:03:55.623: summary: 01 01 00 05 43 49 53 43 4F 00 00 00 00 00 00 00   ....CISCO.......

*Jul 22 15:03:55.623: summary: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00   ................

*Jul 22 15:03:55.623: summary: 00 00 00 00 00 00 03 6E 9B 01 25 07 31 33 30 37   .......n..%.1307

*Jul 22 15:03:55.623: summary: 32 32 31 34 34 39 35 36 F6 B7 B6 BA 20 69 9B 1F   22144956v76: i..

*Jul 22 15:03:55.623: summary: 38 4A 17 98 23 71 BC AC 01 01 00 02 00            8J..#q<,.....  

*Jul 22 15:03:55.623:

*Jul 22 15:03:55.623: VTP LOG RUNTIME: Transitioning from NULL to CISCO domain

*Jul 22 15:03:55.623: VTP LOG RUNTIME: Summary packet rev 878 greater than domain CISCO rev 0

*Jul 22 15:03:55.623: VTP LOG RUNTIME: Domain CISCO currently not in updating state

*Jul 22 15:03:55.623: VTP LOG RUNTIME: Summary packet with followers field zero

*Jul 22 15:03:55.623: VTP LOG RUNTIME: Transmit vtp request, domain CISCO, start value 0

*Jul 22 15:03:55.823: VTP LOG RUNTIME: Summary packet received, domain = CISCO, rev = 878, followers = 2, length 77, trunk Et1/1

[engebied1]

Thank you guys for the replies , fischer.rolf thanks for the links , and confirming my information , but what confuses me is that based on the information in the links ,the answer in the cisco material is wrong , because as you see in the picture the request advertisements fields does not have the configuration revision number , so the

configuration revision numbe does not exist in all VTP messages , that was my original inquiry.

Thanks

[Rolf Fischer · Accepted solution]

Hi Mohammed,

this is something which will accompany you when doing certification preparation and exams.

Once in a while a question may be somewhat imprecise or answers even wrong.

One strategy can be the exclusions of answers that are definitely wrong without any doubt.

In your example that applies to answers 1, 2 and 5. You have to choose 2, so I'd select 3 and 4 - even when you know that 3 is not really true. In the exams you can comment such questions, but unfortunately it doesn't help when you fail.

But don't worry: You don't need 100% to pass!

Good luck,

Rolf