Subject: RE: [Isis-wg] Question on DCC Architecture

From: Yuchen Zhou <[email-masked]>
Date: Sat, 16 Dec 2000 14:19:02 -0800

On a related thread to Ed's question ...

You can use mediation devices to network EMS/OS with GNE/NE (which run OSI
over DCC) over DCN. On the other hand, there are also some proposals to
tunnel IP through OSI networks.

Regards.

Yuchen

-----Original Message-----
From: Tony Li [mailto:[email-masked]]
Sent: Friday, December 15, 2000 9:51 PM
To: Edward Chang
Cc: [email-masked]
Subject: [Isis-wg] Question on DCC Architecture

Ed,

Welcome to the wonderful world of SONET.

 | I am a developer of DCC for an NE. I have few questions regarding DCC
 | architecture.
 | 
 | In the system that I am developing, the network between GNE and EMS/OS
 | is IP, it is naturally for me to consider TCP/IP on the top of DCC. This
 | architecture makes the DCN including DCC consistent, and makes the DCC
 | implementation easy.  However, when I read the SIF document SIF-018-1998
 | and TELCO document GR-253-CORE, I found that the OSI on DCC is a
 | standard and TCP/IP on DCC is not. Here comes my question:
 | 
 | Is there any standard about TCP/IP on DCC that I don't know?  

Nope.  It would make sense, wouldn't it?

 | If there is no such standard, is any one or company implementing such
 | architecture of DCC?  If there is no such standard, is any one or
 | company writing such standard?

I'm unaware of anyone writing such a document nor is it particularly clear
as to where this type of feature should be standardized.  It would make
some sense to do this in the IETF, but it's certainly not the only possible
place.

I do know that many folks have discussed doing this.

Tony

p.s. I've excluded MPLS, as I don't see the relevance...
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---

From: "Cypryan Klish" <[email-masked]>
Date: Mon, 18 Dec 2000 15:26:48 -0500

> OK, but the DCN is not the DCC.

Wrong.  This is a very common misunderstanding, however, the definitive
ITU-T recommendation states otherwise.

Specifically, ITU-T M.3010 (02/00) 11.2 states:

"The DCN may consist of a number of individual subnetworks of different
types, interconnected together.  The DCN may be a local path, or a wide area
connection among distributed functional blocks.  The DCN is technology
independent and may employ any single or combination of transmission
technologies."

Previous editions of M.3010 such as (05/96) contained a similar definition.
In fact, section 4.1.4. of M.3010 (05/96) stated:

"...The various types of subnetworks may include technology specific
subnetwork(s) such as the SDH DCC."

In other words the DCC is part of the DCN; the two are not separate.

SIF's Architecture Work Group found a need to clarify this further by
adapting the terms "access DCN" and "embedded DCN" per the proposal
contained in SIF-AR-9808-120; this became common usage in the final year of
that work group's activity (1999).

As to the scope of the SIF work, it addressed only an IP-based "Access DCN"
- the part of the DCN between an OSS and a GNE; see the approved document
SIF-033-1999 "Requirements for the TCP/IP Protocol Suite on the SONET Access
DCN."  This approved document does contain requirements (sections 7.5) for
FTP-based file transfers and for a FTP/FTAM translation device, so an
infrastructure for software download was put in place, so I don't know what
would be considered incomplete about software download support. In fact,
Annex C of SIF-033-1999 contains SIF's addional TL1 messages specific to
file transfer.  However, I don't know if anyone ever implemented these.

The SIF IP on the DCC activity was never completed, although some of the
contributions identified earlier in this thread are informative as to the
issues and discussions. However, note they are just contributions and not
approved solutions.

Kip Klish

-----Original Message-----
From: Mike Truskowski [mailto:[email-masked]]
Sent: Monday, December 18, 2000 11:08 AM
To: [email-masked]
Cc: [email-masked]; [email-masked]; [email-masked];
[email-masked]; [email-masked]; [email-masked]; [email-masked];
[email-masked]; [email-masked]; [email-masked]
Subject: Re: [Isis-wg] Question on DCC Architecture

OK, but the DCN is not the DCC.

The NSIF, formerly the SIF, worked on the mediation
issues dealing with OSI and TCP/IP.  The work was
incomplete since it dealt with datagrams and not
software download.   

Are you saying that the SG15 is working on mediation
in the DCN to include software download?  

Mike

> 
> Just to clarify a point...
> 
> The ITU-T SG15 Q14 has recently started work on a generic DCN
> architecture and there was agreement in the last experts meeting in Dec,
> 2000 that this DCN would be IP based and would address the issue of
> interworking between an OSI based DCN and IP based DCN.
> 
> Regards,
> Shiva
>

---

From: Jonathan Sadler <[email-masked]>
Date: Tue, 19 Dec 2000 10:14:12 -0600

At 19:25:25 12/18/2000 -0500, [email-masked] wrote:
> 
> At 04:01 PM 12/18/2000 -0600, you wrote:
> >However, use of PPP on the Section DCC may cause an interoperability
> >issue if you have a regenerator in line, and it only supports
> >CLNP/LAPD.  For that reason, GRE encapsulation (ala the Cisco 15303), or
> >IP over LAPD (ala RFC 1663?) may be a better approach, until a standards
> >body puts a stake in the sand.
> 
> How would any of these solve this problem?  If the regenerator can't
> handle IP frames, it will drop them regardless of the encapsulation.
> And this is not just a problem for regenerators, it's an interop
> problem for any multi-vendor ring.

Agreed.  However, autoconfiguration of a link becomes harder if the link
layer protocol is not consistant for Dual and OSI-only interfaces.

Of course use of GRE is the band-aid of last resort to connect IP
islands.

> >Another issue not covered is the operational use of IS-IS on this
> >channel.  As IS-IS is used by SONET terminal/regenerator gear, what is
> >going to happen to all the CPU and memory constrained ADMs out there
> >when they start receiving the LSPs with all of the TE and GMPLS TLVs?
> >Many are limited to less than 50 nodes and less than 100 links in an
> >Area -- and the Node/Link TLVs are certainly smaller than the TE/GMPLS
> >TLVs.
> 
> That's only the tip of the iceberg on this issue.  According to
> RFC 1195 (Integrated IS-IS), you can't have any OSI-only routers in
> a dual-protocol area.

Again agreed.  However, it is possible to have OSI only links on a dual
router.  Some vendors are utilizing this capability to add Integrated
IS-IS support to their nodes in anticipation of IP over DCC being
standardized.

> If you do, you won't get any error messages --
> you'll just get black holes.

Actually, 1195 does require generation of ICMP host unreachable and CLNP
destination unreachable messages when a dual router identifies that the
next hop is, respectively, IP or OSI incapable.

> >Jonathan Sadler
> >
> >[email-masked] wrote:
> >>
> >> Alex Zinin writes:
> >> >  A number of companies working in the SONET area already use or are
> >> >  planning to use DCC for IP control plane [I put MPLS list back ;),
> >> >  since this question is related to GMPLS and OTN-related work].
> >> >
> >> >  There are two types of IP encapsulation on DCC that I know of:
> >> >  LAP-D and PPP/HDLC. We use the second one in our SONET products.
> >> >
> >> >  I think writing up an IETF document describing this would make sense.
> >>
> >> Describing which part?  I think there are at least three separate
> >> issues here.  One is the control plane issue (specifying the use of IP
> >> over DCC for carrying control messages), another is the encapsulation
> >> (for which RFCs 1332, 1661, and 1662 should do fine), and a third is
> >> having ITU-T specify that PPP is a "legal" option for DCC.
> >>
> >> For the first two issues, I think those are already handled.  It's
> >> just that third one that might be an issue for some users, and I don't
> >> think that can be done within an IETF working group.
> >>
> >> If you're suggesting a BCP saying that IP/PPP/HDLC/DCC is a good
> >> thing, I suppose that's possible, but I don't see what it
> >> accomplishes.
> >>
> >> --
> >> James Carlson, Internet Engineering       <[email-masked]>
> >> SUN Microsystems / 1 Network Drive         71.234W   Vox +1 781 442 2084
> >> MS UBUR02-212 / Burlington MA 01803-2757   42.497N   Fax +1 781 442 1677
> >> Second Edition now available - http://people.ne.mediaone.net/carlson/ppp

---

From: Jeff Learman <[email-masked]>
Date: Tue, 19 Dec 2000 17:22:26 -0500

Folks,

I don't think this thread (IP on SONET DCC) has anything to do with
IS-IS over IP.  Please pick a new topic if you have something
to say about that.

Thanks,
Jeff

>there are small security advantages to NOT having is-is over ip
>
>randy