Subject: comments on lcna-minreq-02

From: Pekka Savola <[email-masked]>
Date: Sat, 7 Sep 2002 23:02:46 +0300 (EEST)

A few comments on lcna-minreq-02.

2.2.3 Anycast
    An LCNA might use the anycast address in some instances, e.g. DNS
    server discovery, but never assign anycast addresses to its own
    interface ([rfc2526]).
    
    [Note]:
    According to [rfc2373] section 2.6, anycast address is not assigned
    to a host, but discussion is still going on.

==> perhaps note can be removed, as it changes nothing.  You can still 
specify that lcna does not do anycast even if 2373 was changed.

2.3 Examples of LCNA applications
    Here are several examples of LCNA usage models, especially for home
    network applications. 

==> these should be moved to an appendix.

3.1.2 Routing Header
    [Sending]
    LCNAs may not originate Routing Header. 

==> what do you mean by "may not"? (do not have to be able to?)

    [Receiving]
    As [rfc2460] regulates, the processing of segment_left as zero is 
    unconditionally mandatory.  

==> well, there's nothing to process, but LCNA has to be able to parse 
routing header, yes.

    If the Segment Left field has a non-zero 
    value and RH type is zero, the LCNA SHOULD forward the packet to the
    next intermediate node, even when the node is a host. 
    However, if the LCNA has limited resource, it can respond to this RH
    with parameter problem ICMP. 

==> this has problems, see (hopefully) node reqs draft or 
draft-savola-ipv6-rh-hosts-00.txt

3.2 Path MTU Discovery for IP version 6 [rfc1981]
    When an implementation can guarantee that the sending packet size
    can be restricted to less than the IPv6 MINMTU

==> s/less than/less than or equal to/

3.3 Neighbor Discovery for IP Version 6 (IPv6) [rfc2461]

    In this document, we assume that an LCNA has only one network
    Interface, but it does not prohibit multiple interfaces.  When
    an LCNA is assumed to have multiple interfaces, the following
    must be considered requiring more resources.
    - Types of routing information (such as destination cache and
      routing table)
    - Number of cache entries will increase
      * ND cache
      * Default router list
      * Prefix list

==> are you making an implicit assumption that there couldn't be multiple 
prefixes advertised over one physical interface?

3.5 Internet Control Message Protocol (ICMPv6) for the Internet Protocol
    Version 6 (IPv6) Specification [rfc2463]
    On LCNAs, ICMP used only by a router MAY be omitted (Table
    2).  ICMPs for Echo Request/Reply and minimum error reporting MUST
    be implemented.  The necessary function for ICMPv6 may be added  
    depending upon the finalization of Mobile IPv6 specification.
    An LCNA MUST have some mechanism for Rate limitation.

==> rate limitation of what? ICMP error messages (as noted by ICMPv6 spec) 
or for e.g. ICMP echo req/reply too?

               Table 2. Mandatory ICMP messages for LCNA
        ===============+===============================+==========
        Type            Code                            Necessary?
        ===============+===============================+==========
[...]
        2:              0: Packet too big               No
        Packet
        Too Big
        Message

==> if an LCNA receives a packet that's too big and can't process it, how 
would it react (it's able to deal with at least 1500 bytes right?)?

5.1 DNS Extensions to support IP version 6 [rfc1886] and IPv6
    Stateless DNS Discovery [DDIS]

    If an LCNA is a passive node, it will not become an initiator
    of communication.  This means that name resolution function MAY 
    be omitted (the implementation of resolver can be omitted on a

    On the other hand, if an LCNA is an active node, DNS name resolution
    is necessary.  In such cases, automatic DNS server discovery is
    important.  On this topic, discussions are ongoing in IETF IPv6
    WG.  If a standard is finalized, it might become a mandatory item
    for LCNAs. 

    AAAA is mandatory if an LCNA needs DNS name lookups.  A6 record
    is currently proposed and discussed in IETF for an alternative to
    AAAA record.  We need to check the progress. 
    The IN6.ARPA. domain and nibble-style are mandatory if an LCNA needs 
    DNS reverse name lookups.  However, the IP6.INT. is more widely used
    than the IN6.ARPA. at this time.

==> I think the first paragraph is a bit out of sync; passive nodes may do 
DNS lookups (specifically, often reverse DNS lookups).

-- 
Pekka Savola                 "Tell me of difficulties surmounted,
Netcore Oy                   not those you stumble over and fall"
Systems. Networks. Security.  -- Robert Jordan: A Crown of Swords

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---

From: OKABE Nobuo <[email-masked]>
Date: Tue, 10 Sep 2002 14:46:40 +0900 (JST)

Hi Pekka,

Thank you for your feedback.

We talked about the draft with chairs in Yokohama.
They gave us the following suggestions:
1) IPv6 WG should not pursue separate requirements documents for 
   different types of IPv6 nodes.
2) Instead, the minimal requirements for all IPv6 nodes to
   be reflected in the IPv6 Node Requirements effort.

We agreed the above, and stopped to update the draft.

Sorry for confusing you.

From: Pekka Savola <[email-masked]>
Subject: comments on lcna-minreq-02
Date: Sat, 7 Sep 2002 23:02:46 +0300 (EEST)

>                Table 2. Mandatory ICMP messages for LCNA

---- nobuo