Subject: Re: [rbridge] Fwd: [Pppext] draft-ietf-pppext-trill-protocol-01.txt

From: Linda Dunbar <[email-masked]>
Date: Fri, 02 Jul 2010 09:41:11 -0500

I just read through the draft. I always thought that TRILL is running over
802.3 MAC media. What are the application scenarios for PPP link between
RBridges? Can the draft add a section to explain it? 

Best regards, 
Linda Dunbar

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On
Behalf Of Donald Eastlake
Sent: Tuesday, June 29, 2010 8:36 AM
To: [email-masked]
Subject: [rbridge] Fwd: [Pppext] draft-ietf-pppext-trill-protocol-01.txt

It would be appreciated if a few more people could look at this draft
and either suggest changes or say that they approve of it. If you are
not on the ppp mailing list, you can post such messages here and I'll
forward them to ppp.

Thanks,
Donald

---------- Forwarded message ----------
From: James Carlson <[email-masked]>
Date: Tue, Jun 29, 2010 at 7:45 AM
Subject: [Pppext] draft-ietf-pppext-trill-protocol-01.txt
To: [email-masked]

Has anyone else read this?  Are there any other comments on it?

http://www.ietf.org/id/draft-ietf-pppext-trill-protocol-01.txt

I'd like to get this draft moving forward, and it would help if there
were other eyes on the text.

Thanks.

--
James Carlson         42.703N 71.076W         <[email-masked]>
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---

From: James Carlson <[email-masked]>
Date: Fri, 02 Jul 2010 11:20:08 -0400

> RBridges? Can the draft add a section to explain it? 

Sure; I can add a section to explain this.

The short answer is that the inner frames handled by TRILL are always
802.3-type frames, but the outer frames need not be so.  Once a TRILL
RBridge encapsulates a frame, the way it's transported through the TRILL
cloud towards the egress RBridge is a separate matter.  The TRILL base
protocol document makes this clear in section 2.3.

The application scenarios are similar to the ones that apply for PPP's
Bridging Control Protocol (BCP): any time you would want to carry
tunneled Ethernet traffic from one location to another through a
point-to-point link (such as, say, SONET), you could do so with RBridges
instead.

If you do BCP, then you end up using raw Ethernet frames and Spanning
Tree on your PPP links.  If you do TRILL instead, then you have TRILL
encapsulated Ethernet frames and the TRILL IS-IS-derived control
protocol on your links.

The deployment assumption is that both ends of the PPP link are
themselves RBridges.  If they're not, then the TRILL Control Protocol
described in this draft cannot be negotiated, and some other mechanism
(BCP or routing or just giving up) will be needed.

---

From: Linda Dunbar <[email-masked]>
Date: Fri, 02 Jul 2010 11:21:22 -0500

James, 

PPP's Bridging Control Protocol is for 802.1G, which connect two half
bridges via T1 or something. But 802.1G is hardly used anywhere. 

If two RBridges are connected by SONET, it is GFP (not PPP). That is why I
am a little puzzled. 

Linda

---

From: Donald Eastlake <[email-masked]>
Date: Fri, 2 Jul 2010 12:38:43 -0400

This is the first paragraph of Section 2.3 of the TRILL base protocol
specification:

   The Layer 2 technology used to connect Rbridges may be either IEEE
   [802.3] or some other link technology such as PPP [RFC1661].  This is
   possible since the RBridge relay function is layered on top of the
   Layer 2 technologies.  However, this document specifies only an IEEE
   802.3 encapsulation.

There is further mention of PPP in Section 2.2 and even Figure 2.3 showing PPP.

PPP or any link technology used to connect routers can be used to
connect RBridges and thus connect elements of an RBridge campus.

Thanks,
Donald

---

From: James Carlson <[email-masked]>
Date: Fri, 02 Jul 2010 12:49:31 -0400

> bridges via T1 or something. But 802.1G is hardly used anywhere. 

PPP itself doesn't care what the underlying mechanism might be.  T1 is a
possibility, but there are certainly others.

> If two RBridges are connected by SONET, it is GFP (not PPP). That is why I

Where is it specified that one must use ITU-T G.7041 rather than IETF
RFC 1662?

In any event, that was just an example.  There are many types of links
that can (and do) run PPP.