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baby giant error

Which MTU size can cause a baby giant error?
A. 1500
B. 9216
C. 1600
D. 1518

 

what is the answer ?

12 REPLIES
Super Bronze

Re: baby giant error

C
Super Bronze

Re: baby giant error

Standard Ethernet frame MTU is 1500 bytes. This does not include the Ethernet header and Cyclic Redundancy Check (CRC) trailer, which is 18 bytes in length, to make the total Ethernet frame size of 1518. In this document, MTU size or packet size refers only to Ethernet payload. Ethernet frame size refers to the whole Ethernet frame, including the header and the trailer. Baby giant frames refer to Ethernet frame size up to 1600 bytes, and jumbo frame refers to Ethernet frame size up to 9216 bytes.

 

From:

https://www.cisco.com/c/en/us/support/docs/switches/catalyst-4000-series-switches/29805-175.html#topic3

Community Member

Re: baby giant error

so answer is "D" right ? 

Re: baby giant error

No, when you look at what Joseph posted you would see this...

802.1q trunking 4 1500 + 4 + 18 = 1522 No MTU commands required.

So based on that the 1522 answer would not be correct because 1522 does not require any MTU changes. Also as Joseph pointed out Baby giant frames are up to 1600 bytes. Now based on all that frames that are 1523 to 1600 bytes would be considered Baby Giants.

 

Mike

Re: baby giant error

Answer is C

 

Regards,

Deepak Kumar

Community Member

Re: baby giant error

i think answer should be "D".

Re: baby giant error

What is you logic and documentation to support "D" as being the answer?

 

When the Cisco documentation says clearly "D" is not correct.

 

Mike

Community Member

Re: baby giant error

Standard Ethernet frame MTU is 1500 bytes. This does not include the Ethernet header and Cyclic Redundancy Check (CRC) trailer, which is 18 bytes in length, to make the total Ethernet frame size of 1518. In this document, MTU size or packet size refers only to Ethernet payload. Ethernet frame size refers to the whole Ethernet frame, including the header and the trailer. Baby giant frames refer to Ethernet frame size up to 1600 bytes, and jumbo frame refers to Ethernet frame size up to 9216 bytes.

 

** Above from Cisco site :

my understanding is :

1. as he mentioned that MTU ( packet size ) = 1500 bytes +18 ( header & CRC)=1518= ethernet frame size.

2.if MTU =1518( answer D ) +18 ( header & CRC ) = 1536 bytes = ethernet frame size.-->Baby giant frames refer to Ethernet frame size up to 1600 bytes.

3.f MTU =1600( answer C ) +18 ( header & CRC ) = 1618 bytes = ethernet frame size.-->jumbo frame refers to Ethernet frame size up to 9216 bytes.

 

Community Member

Re: baby giant error

that`s mean you have to convert ant MTU to ethernet frame size then

1. if <= 1600 will refer to a baby gain frame.

2. if >1600 & <= 9216 will refer to jumbo frame.

 

answer D ( Correct ) 

1518+18=1536 ( < 1600 So it's refer to baby gain frame )

answer C ( Not correct )

1600 +18=1618 ( > 1600 So it's refer to jumbo frame ).

 

 

Re: baby giant error

Sorry but that is not correct.

Here is the question.

Which MTU size can cause a baby giant error?
A. 1500
B. 9216
C. 1600
D. 1518

 

It does not say packet size in the question so you don't add anything to the answers.

Lets break it down.

A. 1500 - This is a normal size and will not generate a Baby Giant.

B. 9216 - This is a Jumbo frame so again will not generate a Baby Giant.

C. 1600 - This size per Cisco documentation will generate a Baby Giant.

Now the one that seems to be causing this indecision.

D. 1518 - Based on Cisco documentation anything up to 1522 will not need to have the MTU changed and therefore will not generate a Baby Giant.

 

So based on Cisco documentation the only correct answer is C.

 

Mike

Community Member

Re: baby giant error

Yuo're right! The Question is about the MTU Size and not about the entire frame Size.
So Answer D 1518 + 18 = 1536 = Baby Giant is right!
- reading the Question carefully is key!

Re: baby giant error

Yes reading the question very carefully is key both in studying and taking exams.

 

Mike

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