Re: draft-ietf-ospf-iana-00

[Tom Petch <nwnetworks at DIAL.PIPEX.COM>]

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Tom Petch
----- Original Message -----
From: "Kireeti Kompella" <kireeti at JUNIPER.NET>
To: <OSPF at PEACH.EASE.LSOFT.COM>
Sent: Tuesday, April 05, 2005 12:07 AM
Subject: Re: draft-ietf-ospf-iana-00


> On Mon, 4 Apr 2005, Tom Petch wrote:
>
> > I am curious about  the choice of four octet for enterprise code in 2.5.
> >
> > When used in SNMP, these codes have no effective limit on length;
>
> I was under the impression that each number in an OID sequence was a
> 32-bit number.  Is that not right?

Not so.  BER.1 encodes the sub-identifiers of an OID (after the first two) in
what I think of as CCITT encoding, using 7 bits per octet with the other bit as
a flag to say this is (or is not) the last octet.  So a 7 bit sub-identifier
encodes in one octet, 14 bit in two and so on.

I have never seen any other limit imposed and - knowing ISO - I would not expect
there to be one (apart from the overall limit on length of a TLV which is
2**1008 octet - this is ISO:-).

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