How to extend NLA ID into reserved field

[Bob Fink]

At 04:31 PM 2/18/2000 +0800, Yann-Ju Chu wrote:

>We have got one subTLA block and
>if  I futher divide my subTLA as following:
>
>              1/35   1/39   1/43   1/48
>      ---------+------+-----+------+--------------
>      | subTLA | NLA1 | RES | NLA2 |             |
>      ---------+------+-----+------+-------------
>I assign NLA2 to my directly connected customers. And I have confusion 
>about how
>to use RES bit for my NLA2.
>
>There is one line in RFC2374 talking about how to use RES for NAL2:
>To extend the NLA ID into the reserved field if additional room for 
>complexity is needed.
>
>When I have consumes all NLA2 for a given (subTLA, NLA1, RES=0) pair and 
>now some of my
>customer need more address from me, If I extend the NLA2 ID into the reserve
>field, the address for the customer seems not to be continuous. (The 
>previous and the
>new one I assinged) . With the condition, I would rather allocate another NLA1
>to assign NLA2.
>
>Can anybody tell me what's the above line means?
>(To extend the NLA ID into the reserved field if additional room for 
>complexity is needed.)

This refers to the Aggregatable Addressing plan for TLA's in general, not 
the use of TLA=2001 for sub-TLA purposes. It meant that we reserved 8-bits 
between TLA and NLA so either could expand in future plans (not the users 
choice, rather an IETF/IANA/RIR choice). So don't think of this as a part 
of the way the TLA=2001 sub-TLA's are handed out.

Thus your use of a RES field between NLA1 and NLA2 isn't related. In your 
case, you could choose to leave the RES field as a way of expanding either 
your NLA1 field to the right, or your NLA2 field from the left.


Bob