[magma] mrdisc-00 comments
Pekka Savola <pekkas@netcore.fi> Sun, 29 February 2004 05:50 UTC
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Date: Sun, 29 Feb 2004 07:46:42 +0200
From: Pekka Savola <pekkas@netcore.fi>
To: magma@ietf.org
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Subject: [magma] mrdisc-00 comments
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Some comments on the new, revamped document. Good stuff -- but there are some rather minor odds and ends which should be fixed. substantial ----------- Multicast Router Discovery ==> I'd consider rewording this to "Link-local Multicast Router Discovery" (LLMRD) or something like that, to better reinforce the applicability from the start. If done, this would have to be rippled through to the rest of the document. Advertisements are sent 1. Upon the expiration of a periodic timer ==> note that this doesn't say anything about randomization, which is referred to in other sections, such as 3.4! The Query Interval field is set to the Query Interval value in use by IGMP or MLD on the interface. If IGMP or MLD is not enabled on the advertising interface, this field MUST be set to 0. ==> If I recall correctly (can't check, on the airplane... :), query interval and robustness variable were encoded in the IGMP/MLD in some wacky format. What's the presentation format here? Advertisement messages are sent when the following events occur: ==> would it be worth noting, that a configuration change in robustness/query interval values is NOT a reason to regenerate this message -- BUT remind that the next scheduled advertisement message should include the current variable values! Solicitations are sent to the All-Routers multicast address and SHOULD be rate-limited. ==> solicitations are sent only when MRD is enabled, or the interface is re-initialized. It should be obvious as these don't happen all too often. Therefore, I think we should remove this completely. Should a Multicast Router Terminate message be spoofed with the source address of a valid multicast router, a device may discontinue forwarding of multicast source data to that router. This would disrupt the reception of this data beyond the local subnet. ==> the current specification does not even check the source address, other than being link-local, so this spoofing is even more trivial. Slight reword here please :-) This document also introduces three new MLD messages. Each of these messages requires a new ICMPv6 Type value. This document requests IANA to assign three new ICMPv6 Type values to the Multicast Router Discovery Protocol (for IPv6 Advertisements, Solicitations, and Terminations). ==> one should probably specify from which range (Informational, for ICMPv6) these should be allocated from. And for better clarity, one should probably use a presentation format like: IGMP Type Section Message Name X1 3.1 Multicast Router Advertisement Y1 4.1 Multicast Router Discovery Z1 5.1 Multicast Router Termination ICMPv6 Type Section Message Name X2 3.1 Multicast Router Advertisement Y2 4.1 Multicast Router Discovery Z2 5.1 Multicast Router Termination 10. References 10.1 Normative References 10.2 Informative References ==> should really add something, e.g. ND for Normative and draft-ietf-send-ndopt for Informative. editorial --------- Abstract The concept of IGMP snooping requires the ability to identify the ==> s|IGMP|IGMP/MLD| (plus one should spell these out!) Multicast Router Discovery messages are useful for determining which nodes attached to a switch have multicast routing enabled. This capability is useful in a layer-2 bridging domain with snooping switches. By listening to MRD messages, layer-2 switches can determine where to send multicast source data and group membership messages [RFC1112][RFC2236]. ==> yes, the switches need to "listen" to MRD messages as well, but they can also send them -- maybe reword: s|listening|listening and/or sending| ? Advertisement messages are sent when the following events occur: . The expiration of the periodic advertisement interval timer. Note that it this timer is not strictly periodic since it is a random number between MaxAdvertisementInterval and MinAdvertisementInterval. . After a random delay less than ==> following the style of the previous section, I'd rather use "1.", "2." etc. or "o" or "-" than "." as a bullet marker -- the same elsewhere. An Advertisement not meeting the validity requirements MUST be silently discarded or logged in a rate-limited manner. ==> discarding is not optional, so I'd reword: s/or/and may be/ The same elsewhere in the document. . After waiting for a random delay less than SOLICITATION_INTERVAL when an interface first becomes ==> this constant was not mentioned in the protocol constants section. 13. Full Copyright Statement ==> please add IPR boilerplate in a section prior to this. -- Pekka Savola "You each name yourselves king, yet the Netcore Oy kingdom bleeds." Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings _______________________________________________ magma mailing list magma@ietf.org https://www1.ietf.org/mailman/listinfo/magma
- [magma] mrdisc-00 comments Pekka Savola