Subject: [dc] DCREQ Section 5 Outline

From: Linda Dunbar <[email-masked]>
Date: Fri, 6 Jan 2012 22:37:46 +0000

Section 5 of  draft-dalela-dc-requirements needs a lot of changes. 

	- Many statements in Section 5.1 "Basic Forwarding Problem"  are not accurate. E.g. "the need to massively scale virtualized hosts" may break the FDB (or FIB) on switches/routers, but it doesn't really break the L2/L3 technologies traditionally used in data center. L3 networks can't support host mobility is not true either. Host based routing can support mobility.  
  
	- Section 5.1 is really about "basic forwarding for segmented networks"
 
	- Section 5.2 (DC Inter-connectivity problem) is loaded. Should be broken into multiple (sub)sections:

		- Problems associated with various networks in interconnecting data centers (VPN, straight IP, or straight optical)

		- Multi-data center Service interconnection, Layer 4-7 load balancing issues:  i.e. the description on how service needs to be closer to clients, mapping services to location of data centers, etc.

		- Middleware function association in Multi-data center scenario

	- Section 5.3 "Multi-tenancy Problem" should at least include issues associated with double VLAN tagging, non-VLAN partition (e.g. IEEE802.1ah's ISID), etc

	- New sub-section in Section 5 on traffic pattern dictated by policy and middleware boxes functions and locations.  

Linda Dunbar

---

From: "Ashish Dalela (adalela)" <[email-masked]>
Date: Sat, 7 Jan 2012 09:55:33 +0530

Hi Linda, Please see inline. Thanks, Ashish

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of
Linda Dunbar
Sent: Saturday, January 07, 2012 4:08 AM
To: [email-masked]
Cc: Ronald Bonica
Subject: [dc] DCREQ Section 5 Outline

	- Many statements in Section 5.1 "Basic Forwarding Problem"  are
not accurate. E.g. "the need to massively scale virtualized hosts" may
break the FDB (or FIB) on switches/routers, but it doesn't really break
the L2/L3 technologies traditionally used in data center. 

L3 networks can't support host mobility is not true either. Host based
routing can support mobility. 

[AD] Ok, there is no debate here. It's a matter of rephrasing. 
  
	- Section 5.1 is really about "basic forwarding for segmented
networks"

[AD] That wasn't obvious to me. The problems will be true I think even
if there is no segmentation. E.g. if we had a massive L2 domain or a
large L3 network with host routes (no segmentation).
 
	- Section 5.2 (DC Inter-connectivity problem) is loaded. Should
be broken into multiple (sub)sections:

		- Problems associated with various networks in
interconnecting data centers (VPN, straight IP, or straight optical)

[AD] How are the cases you described above different from each other?
Isn't optical transport transparent to MAC/IP layers and above?

		- Multi-data center Service interconnection, Layer 4-7
load balancing issues:  i.e. the description on how service needs to be
closer to clients, mapping services to location of data centers, etc.

[AD] Isn't the "service" here is a DNS mapped to an IP address? So,
eventually to know the location of a service, we need to know the
location of the IP? I'm trying to understand what are we saying beyond
"workload may be moving between datacenters".

		- Middleware function association in Multi-data center
scenario

[AD] Can you elaborate? Isn't this about an application / middleware
being able to a broadcast/multicast discovery or other such middleware?
In which case, will the issue be that datacenters must support multicast
and broadcast?

	- Section 5.3 "Multi-tenancy Problem" should at least include
issues associated with double VLAN tagging, non-VLAN partition (e.g.
IEEE802.1ah's ISID), etc

[AD] Multiple approaches to address each of these problems are already
mentioned in the "approaches" draft. Would we benefit from duplicating
and/or moving the information from that place to here? The concern might
be that we analyzed double VLAN but ignored GRE. But, I agree that it
has to be somewhere, just not sure if we need to put it here. 

	- New sub-section in Section 5 on traffic pattern dictated by
policy and middleware boxes functions and locations.  

[AD] This wasn't clear to me. Can you elaborate?

Linda Dunbar

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