Subject: [Hipsec] Questions in RFC5201

From: ZhangDong <[email-masked]>
Date: Wed, 25 Feb 2009 11:15:33 +0800

Dear All,
 
In these days, I have been studying about HIP. Here i consult you  
something that i am not quite clear in RFC5201.

In chapter 5.1, it is said that the HIP header is logically an IPv6  
extension header. What do you mean about "logically an IPv6  
extension header"? HIP header is designed as a extension header of  
IPv6? It is putted after the IP header and before transport layer  
header? It is handled by the protocol stack in the implement?
Is my understanding right?
If what i say above are true, because the IP layer is stateless, the  
state and timeout retransmission should be maintained by the HIP  
state machine. Right? Is the HIP state machine handled by the  
application layer? Or by the IP layer?

These are my questions. Maybe i miss something important in RFC5201.
Thank you very much.

Best regards.

Dong Zhang
Huawei Symantec Technologies Co., Ltd
TEL：86-10-82829263
FAX：86-10-82829260
ADDRESS：Harbour Networks P&D Center. Building 17, ZhongGuanCun Software Park, No.8, Dongbeiwang West Road, HaiDian District, Beijing, China.

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From: Miika Komu <[email-masked]>
Date: Wed, 25 Feb 2009 14:08:14 +0200

ZhangDong wrote:

Dear Zhang,

> IPv6?

It means that HIP control header has the same "next header" and "header 
length" fields as in IPv6 extension headers.

Nothing prevents sending of HIP control packets over IPv4.

 > It is putted after the IP header and before transport layer
> header?

Usually, there is no transport layer header after HIP control, just 
IP(HIP). The hiccups draft makes an exception to this.

> It is handled by the protocol stack in the implement?

Usually HIP control plane is handled by userspace software. Usually the 
data plane (ESP) is handled by the stack.

> application layer? Or by the IP layer?

The HIP state machine and HIP control plane retransmissions are usually 
handled by a separate software (daemon) running on the system.