L3DSR server side bits open sourced

Igor Gashinsky igor at gashinsky.net
Wed Mar 9 12:30:37 CST 2011


On Wed, 9 Mar 2011, Shane Amante wrote:

:: 
:: On Mar 9, 2011, at 00:35 MST, Igor Gashinsky wrote:
:: > On Wed, 9 Mar 2011, Randy Bush wrote:
:: > 
:: > :: a real use for the diffserv bits!  why not flowlabel in 6?  it's been
:: > :: looking for a use for a decade.
:: > 
:: > Honestly, we figured flowlabel might actually find a use before all the
:: > values of diffserv will :) In all seriousness, we are starting to set the 
:: > spec for v6 l3dsr now, so, if you care, and believe that flowlabel would 
:: > be a better field to "hijack" (or have a suggestion for another, better 
:: > way then same DSCP methodology that we used for ipv4), we welcome input..
:: 
:: :-/  Please don't abuse the flow-label this way, otherwise your proposal could get added to the "graveyard of IPv6 flow-label proposals" draft:
:: http://tools.ietf.org/html/draft-hu-flow-label-cases-03#section-3
:: 
:: There has been *a lot* of discussion in the 6man WG recently to (finally) define the flow-label to be: a) be stateless; and, b) potentially be useful as an input-key, when used in conjunction with {src_ip, dst_ip}, for fine-grained load-balancing over LAG & ECMP paths, (instead of the traditional IPv6 header 5-tuple).  One example where this might be useful is within Layer-2 switches, at IXP's or other parts of the network, where you'd really like them to only have to look at the 3-tuple: {src_ip, dst_ip + flow-label} as input-keys for LAG load-balancing, since they are at a fixed location in the IPv6 header.  The other, longer-term win of this approach is that hosts can be free to define, or re-define, new IPv6 Extension Headers and you won't have to worry about Core routers/switches needing to dig into those Ext. headers (or, past them) to find useful input-keys for load-balancing over LAG & ECMP paths.
:: 

Yeap, this is why I said flow-label might actually find a good use soon 
enough :)

-igor




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