Subject: (ngtrans) IPv6 over IPv4 using GRE tunelling

From: "S.Radhakrishnan" <[email-masked]>
Date: Tue, 22 Apr 2003 10:19:30 +0530

Hi,
      I am presently working on IPv6 transition project. I am have 
doubt on IPv6-over-IPv4 using GRE tuneling  mechanism.
The following is a block diagram for IP as delivery protocol for 
a GRE packet which as an IPv4 packet as payload.

|-------------------------------------------------------------------------------------|
|IPv4 Header   |  GRE header    |   IPv4 packet as Payload   |  
|Protocol field |   Protocol         |                                        | 
|value = 47     |  type = 0x8000 |                                        |
|-------------------------------------------------------------------------------------|

I would like to know as what value the protocol type in GRE header
should have to carry IPv6 packet as payload with IPv4 as the
delivery protocol for the GRE packet?

|-------------------------------------------------------------------------------------|
|IPv4 Header   |  GRE header    |   IPv6 packet as Payload   | 
|Protocol field |   Protocol         |                                        | 
|value = 47     |  type = XXXX     |                                        |
|-------------------------------------------------------------------------------------|

I will be very grateful if someone can help me by answering my query.

Thanking you
Radhakrishnan

---

From: "Mat Ford" <[email-masked]>
Date: Tue, 22 Apr 2003 09:39:11 +0100

The ethertype for IPv6 is 0x86DD. Your example is incorrect - the ethertype
for IPv4 is 0x0800.

Mat

-----Original Message-----
From: [email-masked]
[mailto:[email-masked]]On Behalf Of S.Radhakrishnan
Sent: 22 April 2003 05:50
To: [email-masked]
Subject: (ngtrans) IPv6 over IPv4 using GRE tunelling

Hi,

|---------------------------------------------------------------------------
----------|
|IPv4 Header   |  GRE header    |   IPv4 packet as Payload   |
|Protocol field |   Protocol         |
|
|value = 47     |  type = 0x8000 |                                        |
|---------------------------------------------------------------------------
----------|

|---------------------------------------------------------------------------
----------|
|IPv4 Header   |  GRE header    |   IPv6 packet as Payload   |
|Protocol field |   Protocol         |
|
|value = 47     |  type = XXXX     |
|
|---------------------------------------------------------------------------
----------|

Thanking you
Radhakrishnan

---

From: "S.Radhakrishnan" <[email-masked]>
Date: Tue, 22 Apr 2003 14:17:50 +0530

Dear Mr.Mat,
  My query is on protocol type field in GRE header. If you are aware, GRE
header has protocol type field which specifies what payload packet it has
encapsulated.
My question is what should be the value of protocol type field in GRE header
if GRE payload is an IPv6 packet. As per RFC 1701, the protocol type field
in GRE header will have value 0x8000 if the GRE payload is IPv4 packet.
  Expecting your reply.

 Radhakrishnan

---

From: "S.Radhakrishnan" <[email-masked]>
Date: Wed, 23 Apr 2003 09:42:35 +0530

Dear Mr.Mat,
  Your answer is very correct. Sorry for my previous mail yesterday where i
said you are wrong.
I am very thankful to you for your help.

regards
Radhakrishnan