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PAR for Media Converters r2IEEE 802.1 interim, October, 2004 1 PAR for Media Converters revision 2 Norman Finn Cisco Systems.

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Presentation on theme: "PAR for Media Converters r2IEEE 802.1 interim, October, 2004 1 PAR for Media Converters revision 2 Norman Finn Cisco Systems."— Presentation transcript:

1 PAR for Media Converters r2IEEE interim, October, PAR for Media Converters revision 2 Norman Finn Cisco Systems

2 PAR for Media Converters r2IEEE interim, October, What is a Media Converter

3 33 PAR for Media Converters r2IEEE interim, October, 2004 A demarcation device on the Customers premises is useful for defining and verifying services. This is inherently a two-port function. Shared media are never present, at least on the up-link. Why invent a Media Converter? Why not use a two-port Bridge?

4 44 PAR for Media Converters r2IEEE interim, October, 2004 So, neither of a bridges two most obvious functions, MAC address filtering and loop prevention, are needed. Almost all other bridge functions are extensions of the filtering and loop prevention functions. Every one of those bridge functions begs for options, configuration, and management. Why invent a Media Converter? Why not use a two-port Bridge? (continued)

5 55 PAR for Media Converters r2IEEE interim, October, 2004 As suggested by the name, a Media Converter often converts between different media, e.g. SONET or DSL, and Ethernet. A Media Converter sometimes converts between different-speed media. Management of a Repeater would be visible to, and could be subverted by, the Customer. Why invent a Media Converter? Why not use a Repeater (Hub)?

6 66 PAR for Media Converters r2IEEE interim, October, 2004 Existing Media Converters have serious faults, and correcting them is difficult in the absence of any standard. (The primary fault is that a failure of one link is not relayed to the other link.) IEEE 802 knows Ethernet best. This standard must be medium independent. Why invent a Media Converter? Why should become involved?

7 77 PAR for Media Converters r2IEEE interim, October, 2004 It is a two-MAC relay device. It is as transparent as possible, both to Bridges and to Layer 2 Stations. It does not make forwarding decisions except, perhaps, to support its brain and to support IEEE Std ah OAM. It must be remotely diagnosable, but only through the Provider port. A failure of one link must be signaled to the other link. So, what is a Media Converter?

8 PAR for Media Converters r2IEEE interim, October, Two-MAC Relay Device

9 99 PAR for Media Converters r2IEEE interim, October, 2004 Media Converter is a Relay/Brain function with two MAC/PHYs. A MAC/PHY may be an 802 medium (typically 802.3) or an emulated 802 medium (e.g. Ether-over-SONET) must supply the hooks for other organizations to fit their Ether-over-XYZ specifications into this model. Two-MAC Relay Device Up PHY Up MAC Down MAC Down PHY Relay / Brain

10 PAR for Media Converters r2IEEE interim, October, Transparent to Bridges and Stations

11 11 PAR for Media Converters r2IEEE interim, October, 2004 All protocols (Spanning Tree, GARP, 802.1X, LLDP, LinkSec, KeySec) must pass through. All higher layer protocols must pass through. Media Converters own MAC address (if used) must be intercepted. Transparent to Bridges and Stations Up PHY Up MAC Down MAC Down PHY Relay / Brain

12 12 PAR for Media Converters r2IEEE interim, October, X Pause cannot pass through transparently. We must decide what role Pause plays. (None? Speed matching? Uplink only?) 802.3ah OAM should manage at least the Up link, and perhaps the Down link. We must decide whether LinkAgg passes through. (Transparent? Drop? Play?) Transparent to Bridges and Stations Up PHY Up MAC Down MAC Down PHY Relay / Brain

13 PAR for Media Converters r2IEEE interim, October, Must Support a Brain Function

14 14 PAR for Media Converters r2IEEE interim, October, 2004 Handling 802.3X Pause and 802.3ah OAM takes a certain amount of intelligence. We must decide whether access to the MAC address of at least one of the ports, for unicast traffic, should be allowed by the standard. This would allow better control of the device. However, this might open too many doors to extensions. Do we really want a spectrum of devices between Bridges and Repeaters? Must Support a Brain Function

15 PAR for Media Converters r2IEEE interim, October, Remotely Diagnosable

16 16 PAR for Media Converters r2IEEE interim, October, 2004 IEEE Std ah OAM can easily manage Link 1. We must manage Link 2. Tunnel.3ah OAM over.3ah OAM? Use Layer 2 SNMP to control MCs MIBs? Probably not CFM MIP between PB and CE. Remotely Diagnosable Media Converter Provider Bridge Customer Equipment 12

17 17 PAR for Media Converters r2IEEE interim, October, 2004 Loopback is required. A and B paths, at least. C path is very desirable, if Customer cooperates. Extending 802.3ah OAM fills this requirement nicely. Remotely Diagnosable Media Converter Provider Bridge Customer Equipment ABC

18 PAR for Media Converters r2IEEE interim, October, Signaling Link Failures

19 19 PAR for Media Converters r2IEEE interim, October, 2004 A failure of Link 2 must be reported to the Provider Bridge. A failure of Link 1 must be reported to the Customer Equipment. How? Dropping the link (Link Integrity Clauses of IEEE 802.3) is guaranteed to work. Might 802.3ah OAM be extended as an alternative? For one or both problems? Signaling Link Failures Media Converter Provider Bridge Customer Equipment 12

20 PAR for Media Converters r2IEEE interim, October, Other Possibilities

21 21 PAR for Media Converters r2IEEE interim, October, 2004 Adding 802.1p queues are possible, but … This would require 802.1Q or 802.1ad tags. Which? How many queues? What draining algorithm? Making the device symmetrical would allow its use in more scenarios, but … Making it symmetrical might make it unfit for the Provider – Customer use. Other Possible Functions

22 PAR for Media Converters r2IEEE interim, October, Project Authorization Request

23 23 PAR for Media Converters r2IEEE interim, October, 2004 This standard specifies the function of a Two-Port MAC Relay, and the protocols and procedures to support its operation. A TPMR is transparent to all frame-based protocols except some or all of those defined by IEEE Std , is remotely diagnosable via 802.3ah OAM through one of its ports, and signals a failure of either MACs link to the other MAC. PAR: Scope

24 24 PAR for Media Converters r2IEEE interim, October, 2004 The wide and growing deployment of Ethernet Provider Services has created a demand for simple two-port demarcation devices that connect two 802 media or 802 media emulations. The lack of standards for such devices, and particularly for link- loss signaling and remote diagnosis, is impeding the growth of this industry. A Two-Port MAC Relay standard will greatly improve this situation. PAR: Purpose

25 25 PAR for Media Converters r2IEEE interim, October, 2004 Public networks represent a new and very broad application space for IEEE 802 technologies and specifically for Provider Bridges (P802.1ad) and Ethernet in the First Mile (802.3ah). Numerous vendors and potential users (the Service Providers) have expressed the need to integrate Ethernet link technologies with their existing infrastructure at a low cost, while providing the manageability and remote diagnostic capabilities traditionally offered by circuit switched technologies. Five Criteria: Broad Market Potential

26 26 PAR for Media Converters r2IEEE interim, October, 2004 The Two-Port MAC Relay will be compatible with other point-to-point 802 LANs and stations, and with all Bridge standards. A minimum set of managed objects, compatible with the minimized functionality of the TPMC, will be defined. Five Criteria: Compatibility

27 27 PAR for Media Converters r2IEEE interim, October, 2004 Existing 802 standards define Repeaters, which are transparent and have no MACs, and Bridges, which are less transparent, and have MAC address filtering and loop prevention capabilities. The TPMR has MACs and frame buffers, intermediate transparency, and no address filtering or loop prevention. As a separate document from media standards and from the Bridge standards, it will be easily found. Five Criteria: Distinct Identity

28 28 PAR for Media Converters r2IEEE interim, October, 2004 Numerous vendors supply devices with either more or less functionality than the Two-Port MAC Relay. The few novelties in the definition of the various functions are straightforward extensions of existing capabilities. Five Criteria: Technical Feasibility

29 29 PAR for Media Converters r2IEEE interim, October, 2004 The existence of relatively low-volume Media Converters and high-volume two- port Home Routers demonstrates that the TPMR should be economically viable. Installation cost is known to outweigh unit cost in Home Routers; the elimination of required configuration in the TPMR promises to reverse this imbalance. Five Criteria: Economic Feasibility

30 30 PAR for Media Converters r2IEEE interim, October, 2004


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