Subject: [Mipshop] Alignement for MH LLA option

From: Martin André <[email-masked]>
Date: Wed, 18 May 2005 15:49:05 +0900

Hello,

FMIPv6 draft (section 6.4.4) says that an MH LLA option must be aligned 
appropriately. The problem is that we can see different manners
to align this option appropriately:

- looking at Figure 15 (MH LLA option), the padding that comes naturaly
is 8+6 in order to have the option length a multiple of 8 bytes.

- with a padding of 8n+4, LLA starts on a multiple of 8 octets, and this
keeps some place at the end for LLA with length up to 8 bytes.

In the case of a 6 byte address both 8n+4 and 8n+6 would let a router 
read the entire option with two operations. Yet the 8n+4 alignment would 
let you read the option in in two opertations even if address length 
changes a bit (up to 8) while 8n+6 would require a router to perform an 
extra read operation. (... eer I hope I was clear).

Thanks for any clarifications
Martin

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