Subject: [rbridge] Ingress Rbridge address and BCN

From: Eric.Gray at marconi.com (Gray, Eric)
Date: Fri, 27 Oct 2006 14:27:21 -0400

Manoj,

	A BCN notification sent to a non-BCN supporting end-station
is "junk traffic" - is it not?  Such an end-station will - at best
- simply ignore the extra traffic, and the switch will just end up
sending more "junk traffic" to that end-station.

	A switch that sends junk traffic to end stations is not the
most useful of devices.  Hence it was suggested earlier (I don't
recall who suggested it) that BCN capable devices would nost likely
share common VLANs such that:

	1) the aggregate of all BCN supporting devices can be protected
	from non BCN supporting devices by protecting the bandwidth of
	the BCN-VLAN(s);

	2) BCN notifications only get sent to BCN capable devices.

Using this approach, a switch only needs to be configurable on a
per-VLAN basis to use, or not use, BCN.

--
Eric

--> -----Original Message-----
--> From: Wadekar, Manoj K [mailto:manoj.k.wadekar at intel.com] 
--> Sent: Friday, October 27, 2006 1:54 PM
--> To: Gray, Eric
--> Cc: rbridge at postel.org
--> Subject: RE: [rbridge] Ingress Rbridge address and BCN
--> 
--> Hi Eric,
--> 
--> 	(My apologies for being slow in my responses..)
--> 	
--> 	I did not understand your comment about: " you have to be
--> careful not to send BCN messages to those end-stations that don't
--> support them." Can you please clarify? 
--> 
--> 	Switches do not have knowledge of which end stations support
--> BCNs and which do not. 
--> 
--> 	Have I missed your point?
--> 
--> Thanks,
--> - Manoj
--> 	
--> -----Original Message-----
--> From: Gray, Eric [mailto:Eric.Gray at marconi.com] 
--> Sent: Friday, October 27, 2006 8:44 AM
--> To: Wadekar, Manoj K
--> Cc: rbridge at postel.org
--> Subject: RE: [rbridge] Ingress Rbridge address and BCN
--> 
--> Manoj,
--> 
--> 	Once again, the assumption that cores do not retain "addresses
--> of
--> all the end-stations in [the] whole cluster" is a "convenient
--> assumption"
--> for making the argument that another mechanism is required.
--> 
--> 	Currently, there would be no requirement for retaining all such 
--> addresses as you have to be careful not to send BCN 
--> messages to those
--> end-stations that don't support them.  Moreover, as mentioned
--> previously,
--> it is trivially easy to determine what address information should be
--> kept.
--> 
--> --
--> Eric
--> 
--> --> -----Original Message-----
--> --> From: rbridge-bounces at postel.org 
--> --> [mailto:rbridge-bounces at postel.org] On Behalf Of 
--> Wadekar, Manoj K
--> --> Sent: Friday, October 27, 2006 11:21 AM
--> --> To: rbridge at postel.org
--> --> Subject: Re: [rbridge] Ingress Rbridge address and BCN
--> --> 
--> --> Yes, for large clusters, if cores do not maintain addresses 
--> --> of all the
--> --> end-stations in whole cluster - then only way to get BCN 
--> --> back to ES, is
--> --> to send them to ingress rbridge-address and then have 
--> that ingress
--> --> rbridge forward BCN to end station with appropriate ES address.
--> --> 
--> --> If so, ingress rbdridge address seems to be requirement to me.
--> --> 
--> --> Thanks,
--> --> - Manoj
--> --> 
--> --> -----Original Message-----
--> --> From: Silvano Gai [mailto:sgai at nuovasystems.com] 
--> --> Sent: Friday, October 27, 2006 8:00 AM
--> --> To: Radia.Perlman at sun.com; Wadekar, Manoj K
--> --> Cc: rbridge at postel.org
--> --> Subject: RE: [rbridge] Ingress Rbridge address and BCN
--> --> 
--> --> 
--> --> If the congestion is detected in the core of the TRILL 
--> --> network, how do
--> --> you signal back to the source host if you don't know 
--> which is the
--> --> ingresss RBridge? 
--> --> 
--> --> You cannot look-up the inner MAC address, because in 
--> the core of the
--> --> network you don't keep the inner MAC addresses in the 
--> --> table. Correct?
--> --> 
--> --> This is a clear reason while you need the ingress 
--> RBridge address.
--> --> 
--> --> -- Silvano
--> --> 
--> --> > -----Original Message-----
--> --> > From: rbridge-bounces at postel.org 
--> --> [mailto:rbridge-bounces at postel.org]
--> --> On
--> --> > Behalf Of Radia.Perlman at sun.com
--> --> > Sent: Thursday, October 26, 2006 5:02 PM
--> --> > To: Wadekar, Manoj K
--> --> > Cc: rbridge at postel.org
--> --> > Subject: Re: [rbridge] Ingress Rbridge address and BCN
--> --> > 
--> --> > Hi Manoj,
--> --> > 
--> --> > I'm confused about BCN. Wouldn't congestion notification 
--> --> need to go to
--> --> the
--> --> > original endnode source,
--> --> > and not the ingress RBridge?
--> --> > 
--> --> > Radia
--> --> > 
--> --> 
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