Re: IPv6 minimum Link MTU

Hi Joe,

  Thanks for your comment.yes,will sure keep in mind about the fragmentation
in IPV6 is done on the source and not on the routers.Is it right,the
exception would be in the below case

  "On any link that cannot convey a 1280-octet
   packet in one piece, link-specific fragmentation and reassembly must
   be provided at a layer below IPv6"

Thanks

Regards
Anantha Subramnanian Natarajan

On Thu, Aug 27, 2009 at 1:48 AM, Joe Astorino <jastorino_at_ipexpert.com>wrote:

> I am not positive on that, but I believe it has to do with efficiency.
> That is, an efficient header:data ratio that the designers felt was the most
> optimized. Also keep in mind that IPv6 routers do NOT do fragmentation : )
> In IPv6, the source host must do fragmentation based on the lowest MTU along
> the path.
>
>
> On Thu, Aug 27, 2009 at 2:42 AM, Anantha Subramanian Natarajan <
> anantha.natarajan_at_gravitant.com> wrote:
>
>> Hi Joe,
>>
>> Got it and thanks for addressing the answer referring to the RFC for
>> IPv4.What about IPv6,is it on similiar lines.( I think,the basic header of
>> ipv6 is 40 octets and it has options for extension headers,so adding both
>> may come to close around 1280 octets ?)
>>
>> Thank You
>>
>> Regards
>> Anantha Subramanian Natarajan
>>
>>
>>
>> On Thu, Aug 27, 2009 at 1:29 AM, Joe Astorino <jastorino_at_ipexpert.com>wrote:
>>
>>> To answer your question about IPv4, from RFC791 (IP)
>>>
>>> "Every internet module must be able to forward a datagram of 68
>>>
>>>
>>> octets without further fragmentation. This is because an internet
>>>
>>> header may be up to 60 octets, and the minimum fragment is 8 octets.
>>>
>>> Every internet destination must be able to receive a datagram of 576
>>> octets either in one piece or in fragments to be reassembled."
>>>
>>>
>>>
>>> On Thu, Aug 27, 2009 at 2:04 AM, Anantha Subramanian Natarajan <
>>> anantha.natarajan_at_gravitant.com> wrote:
>>>
>>>> Hi All,
>>>>
>>>> When I was going through the Doc CD for IPv6,I read about the "Minimum
>>>> Link MTU is 1280 octets in IPv6".Even when referred the RFC 2460 (IPv6
>>>> specification),it highlights the same.I am just curious about the
>>>> significance of that number "1280 octets".How that is derived ?.Even I
>>>> didn't know,what is the significance of the number 68 octets,which is
>>>> minimum MTU size for Ipv4 .
>>>>
>>>> Any clarification is really appreciated.
>>>>
>>>> Thanks for the help
>>>>
>>>> Regards
>>>> Anantha Subramanian Natarajan
>>>>
>>>>
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>>>
>>>
>>> --
>>> Regards,
>>>
>>> Joe Astorino - CCIE #24347 R&S
>>> Technical Instructor - IPexpert, Inc.
>>> Cell: +1.586.212.6107
>>> Fax: +1.810.454.0130
>>> Mailto: jastorino_at_ipexpert.com
>>>
>>
>>
>
>
> --
> Regards,
>
> Joe Astorino - CCIE #24347 R&S
> Technical Instructor - IPexpert, Inc.
> Cell: +1.586.212.6107
> Fax: +1.810.454.0130
> Mailto: jastorino_at_ipexpert.com

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Received on Thu Aug 27 2009 - 01:55:28 ART