Re: [mpls] mail on ISD encodding

[[e-mail]]

>
> Hi Loa,
>
>>> [WG chair hat: off]
>>>
>>> Note that we have a few spare bits in format B.  We COULD in principle,
>>> change the current proposal to allow format D to follow format B. For
>>> example, we could change format B to look like:
>>>
>>> 0                   1                   2                   3
>>> 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>> |   Opcode    |        Data             |U|IHS|S|  NASL |  NAL  |
>>> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>>>
>>
>> What is U, is it what once was called P?
>
>
> Please see the draft.  U is the unknown action handling option.  I have no
> recollection of what P is or was.

Plz look at draft-jags-mpls-ps-mna-hdr (you are a co-author) in
section 4. It allocates the reserved bit in the Format B LSE, as
a bit indicating post-stack data.

/Loa

>
>
>> Yes, I fumbled. I meant:
>>
>> Format B (OpCode X)  + OpCode X data
>> Format C additional OpCode X data
>> Format D additional OpCode X data
>>
>> I think to do this we would need to have a specific OpCode.
>> Maybe NOP could be used, but there is a risk of overloading.
>
>
> The example that you’ve now given is incorrect.  Format C always
> introduces a new opcode.
>
> Tony
>
>
>