Re: [rbridge] Default nickname base approach for multilevel TRILL- draft-tissa-trill-multilevel-00.txt

["Tissa Senevirathne (tsenevir)" <[e-mail]>]

Like stated in other emails, nickname space expansion require proper thoughts.

 

Radia’s multi-level draft require new data plane changes to implement nickname translation or nickname swap. What we are saying is mult-level TRILL can  be implemented with a simpler approach.

 

Nickname expansion needed to be solved with forward and progressive looking approaches for that some careful thinking is required.

 

From: [e-mail] [mailto:[e-mail]] 
Sent: Sunday, February 26, 2012 7:48 PM
To: Sam Aldrin
Cc: Radia Perlman; [e-mail]; [e-mail]; Tissa Senevirathne (tsenevir)
Subject: Re: Re: [rbridge] Default nickname base approach for multilevel TRILL- draft-tissa-trill-multilevel-00.txt

 


Pls see the following: 


The reason why folks in IP word are pushing to go to IPv6 is that the exhausting of IPv4 address, not that the NAT can not work. 
The NAT technology is widely deployed in China, and it does work well. There is very little IPv4 address can be assigned to the BNAS(Most of the address assigned to the user are private IPv4 address, and only the NNAS and above equitment are assigned public address ), so it is an emergent thing to transit from IPv4 to IPv6. 
And your point is? 

[hfw] My point is that the multi-level draft should solve the nickname space issue. 

There is a multi-level draft is proposed by Radia, we can optimize it and make it better. There is no need to provide a new Multi-lelve draft which can not solve the key issue of nickname space. 





Sam Aldrin <[e-mail]> 

2012-02-27 11:40 

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"Tissa Senevirathne (tsenevir)" <[e-mail]>, [e-mail], [e-mail], Radia Perlman <[e-mail]> 

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Re: [rbridge] Default nickname base approach for multilevel TRILL- draft-tissa-trill-multilevel-00.txt

 

		





On Feb 26, 2012, at 6:50 PM, [e-mail] <mailto:[e-mail]>  wrote: 


The reason why folks in IP word are pushing to go to IPv6 is that the exhausting of IPv4 address, not that the NAT can not work. 
The NAT technology is widely deployed in China, and it does work well. There is very little IPv4 address can be assigned to the BNAS(Most of the address assigned to the user are private IPv4 address, and only the NNAS and above equitment are assigned public address ), so it is an emergent thing to transit from IPv4 to IPv6. 
And your point is? 

If we can not slove the nickname space issue now, do we need another NICKNAMEv6 or something else? 
That could be a topic, which could be taken up to resolve nickname exhaustion issue and not necessarily at multilevel draft. 

So i thing the nickname space issue is the key issue we should slove now. 
That topic should be considered outside of this draft. 

Multi-level draft is a good platform to slove it, though there is some technology we should considered futher. 
If multilevel draft is only to address 'nickname exhaustion' issue, then it should be renamed accordingly and not 'multilevel'. The purpose of multilevel draft is different, which is stated in the draft and the by product of it is nickname exhaustion could be alleviated and not just the primary problem/solution. Here is the snip from abstract "..novel method of constructing multi-destination trees using partial nickname space" 

cheers 
-sam 




"Tissa Senevirathne (tsenevir)" <[e-mail] <mailto:[e-mail]> > 
发件人:  [e-mail] <mailto:[e-mail]>  

2012-02-25 02:07 

 

收件人

"Radia Perlman" <[e-mail] <mailto:[e-mail]> > 

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[e-mail] <mailto:[e-mail]> , [e-mail] <mailto:[e-mail]> , [e-mail] <mailto:[e-mail]>  

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Re: [rbridge] Default nickname base approach for multilevel TRILL-        draft-tissa-trill-multilevel-00.txt

 

		





Also, there are so many well known issues with NAT like approaches. #1 is you would lose identity of originator, and it becomes an OAM nightmare.  It limit ability apply certain ACL, rate-limiting etc. 
 
There is a whole series of issues associated with NATs. That is one of the reasons folks in IP world are pushing hard to go to IPv6. I was assuming people are aware of those. 
 
From: Radia Perlman [mailto:[e-mail]] 
Sent: Friday, February 24, 2012 9:23 AM
To: Tissa Senevirathne (tsenevir)
Cc: [e-mail] <mailto:[e-mail]> ; [e-mail] <mailto:[e-mail]> ; [e-mail] <mailto:[e-mail]> 
Subject: Re: [rbridge] Default nickname base approach for multilevel TRILL- draft-tissa-trill-multilevel-00.txt 
 
I assume that all RBridges will need to be in all topologies, so multitopology will not help with nickname exhaustion.  Plus you haven't explained how a TRILL packet would be marked as to which topology the packet should be routed according to (other than what I mentioned, which actually eats up nicknames by a factor of the number of topologies supported). 
 
Plus, rather than just lumping potential issues into a phrase such as "NAT-like", be explicit about what issues there actually are.  I believe the Fulcrum chip would have no problem with translating the nickname fields. 
 
And rather than assuming that nickname exhaustion can be solved "some other way", there should be a palatable solution before rejecting a chance to solve it with multilevel. 
 
Radia 
2012/2/24 Tissa Senevirathne (tsenevir) <[e-mail] <mailto:[e-mail]> > 
Because you can have same nickname for different topology. It is not a nickname that will identify an RBRidge, it is topology,nickname combination that will identify an RBRidge. So RB1 can have nickname 1 in topo-1 and RB2 can have nickname 1 in topo2. Now total nicknames in the campus is 2**16 x topologies. 
 
Stealing bits to represent topo id is only a workaround there can be (are ) more elegant ways of doing it that. 
 
Bottom line is we need to look for more creative methods of solving nickname space issue than doing NAT like behavior. 
 
From: Radia Perlman [mailto:[e-mail] <mailto:[e-mail]> ] 
Sent: Friday, February 24, 2012 9:05 AM
To: Tissa Senevirathne (tsenevir)
Cc: [e-mail] <mailto:[e-mail]> ; [e-mail] <mailto:[e-mail]> ; [e-mail] <mailto:[e-mail]>  

Subject: Re: [rbridge] Default nickname base approach for multilevel TRILL- draft-tissa-trill-multilevel-00.txt 
 
I don't understand how multi-topology helps with the nickname exhaustion issue.  As a matter of fact, the only plausible way of marking a packet for which topology that has been suggested on the mailing list (I asked a efw times if there were any other possibilities), was to steal 2 or 3 bits of the nickname to encode which topology, in effect, making a destination appear as multiple destinations and multiple forwarding table entries (which you'd want anyway, for multitopology). 
 
 
Radia 
2012/2/24 Tissa Senevirathne (tsenevir) <[e-mail] <mailto:[e-mail]> > 
Mutli-topology is the answer to increase the nickname space. 
 
Nickname translation is very similar to NAT, which has it’s own down side, not to mention special hardware etc. to do the translations, additionally. We also know from our experience, in IP world NATing is not the most desired behavior and we live with it. So we should not be going down that path instead need to look forward from that experience. 
 
Multi-topology not only address nickname space issue but also enables various other applications such as overlay topologies, traffic engineering. 
 
The draft-tiss-trill-multilevel present approaches that are generic, which mean it can be applied for multi-topology, or base topology. It utilizes the fundamentals of IS-IS , such as Area hierarchy for reduction of the LSP-DB. It utilize affinity TLV concepts to effectively solve multi-destination issues. 
 
We should not mix-up between Data center interconnects with data center node scaling. They are two different and orthogonal issues. 
 
Objective of multi-level trill is to interconnect different datacenters, and maintain LSP-DB small as possible to avoid scaling and volatility. 
 
Increasing nickname space a different requirement and has nothing to do with data-center interconnects. 
 
 
From: Radia Perlman [mailto:[e-mail] <mailto:[e-mail]> ] 
Sent: Friday, February 24, 2012 6:15 AM
To: [e-mail] <mailto:[e-mail]> 
Cc: Tissa Senevirathne (tsenevir); [e-mail] <mailto:[e-mail]> ; [e-mail] <mailto:[e-mail]> 
Subject: Re: [rbridge] Default nickname base approach for multilevel TRILL- draft-tissa-trill-multilevel-00.txt 
 
People have mentioned to me that they are nervous about running out of nicknames, especially since there are reasonson why they might want to assign nicknames to hypervisors.  With the alternate approach of allowing nicknames to be reused in different areas, it makes automatic nickname assignment much simpler and makes TRILL a lot more scalable. 
 
It does have the downside of requiring mapping of nicknames at the border RBridges. 
 
And by the way, the affinity TLV can be used for multidestination frames transiting between level 1 and level 2. 
 
Radia 
2012/2/23 <[e-mail] <mailto:[e-mail]> > 

Hi, Tissa. 

I have several comments about the draft. 

(1) in section 4.4 (Multicast), "The scope of global traffic may be identified either through VLAN or via finegrain 
label that spans across the entire TRILL campus." 
Vlan and Fine-grain Label is used for service differentiation and isolation. I do not quite understand that how to 
use VLAN and fine-grain Lable to identify the traffic scope. The data traffic with a given VLAN-x, can 
be forwarded to other end station in the local area, or to the end station in remote areas. 

(2) nickname allocation 
The nickname management sub-TLV is proposed in the document. I wonder this mechanism adds the complication of   
nickname allocation. As the section 1 (introduction) of RFC6325, one of the important advantage of TRILL is that   
it avoids the creating subnets of IP address and wasting address. The nickname acquisition  method in this draft violates the   
idea of TRILL Basic specification, and reduces the flexibility of nickname allocation. As the draft assumed, A1 had   
nickname range of 100-200, A2 has a local nickname range of 201-300. If the numbers of A1 area is only 50, so 50   
nicknames in A1 is wasted. As the network growing, the number of some areas may exceed the number being allocation   
by Border RBridges. The design and maintaining of nickname ranges for each area is a very hard work. Even worst, it   
can not avoid to waste nickname space. 

(3) Dynamic ranges 
The nickname range is divided into two range: local range and dynamical range. I wonder the nickname conflict   
resolution can not work if the RBridge get the nickname from the dynamical range while the two RBridge belongs to   
different areas. For example, RB1 is in area A1, and RB2 is in area A2. If RB1 gets the nickname N1 from dynamic   
range, and it will floods in area A1, and other RBridges in area A1 can not get nickname N1 because of nickname   
confliction mechanism, but RB2 in area A2 can not receive the PDU from RB1, and it  can also get the nickname N1 from   
dynamical range. So the question is how to avoid the duplication dynamical range nickname for different areas. 

(4) The risk of running out of nickname maybe a issue for TRILL. The number of 2**16 nickname is enough for the current data center, 
but it maybe not enough in the future, especailly if TRILL over IP , TRILL over MPLS technology or some other data center technologies 
are deployed, the data center network can be a very lardge network. So i think the very important and essential goal of multi-level draft is to save nicknames. 

Best regards 
Fangwei Hu 

"Tissa Senevirathne (tsenevir)" <[e-mail] <mailto:[e-mail]> > 
发件人:  [e-mail] <mailto:[e-mail]>  

2012-02-23 11:55 

 

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<[e-mail] <mailto:[e-mail]> > 

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[rbridge] Default nickname base approach for multilevel TRILL-        draft-tissa-trill-multilevel-00.txt



  

 

		
	





Dear All

We have submitted draft-tissa-trill-multilevel, present multilevel TRILL based on default nickname approach. Additionally we discuss construction of multi-destination trees and related RPF in multilevel TRILL. Please could you review and comment 

Detail of the draft and abstract are below.

Filename:                  draft-tissa-trill-multilevel
Revision:                  00
Title:                                   Default Nickname Based Approach for Multilevel TRILL
Creation date:                  2012-02-21
WG ID:                                   Individual Submission
Number of pages: 26

Abstract:
Multilevel TRILL allows the interconnection of multiple TRILL
networks to form a larger TRILL network without proportionally
increasing the size of the IS-IS LSP DB. In this document, an
approach based on default route concept is presented. Also,
presented in the document is a novel method of constructing multi-
destination trees using partial nickname space. Methods presented in
this document are compatible with the RFC6325 specified data plane
operations.

                                                                               
Thanks
Tissa

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