The MPLS WG Archive

[Marc Binderberger <marc@sniff.de>]

Hello,

> With MPLS I can create MPLS VPNs, QoS can (really?) be
> granted to packet flows, and routing is more faster.

Forget about the "faster". Today the forwarding happens either in 
hardware and is wire-speed for IPv4/IPv6 as well. Or it's the same 
underlying mechanism in software, e.g. the "CEF" table in Cisco 
routers.

QoS for MPLS is in first place the same as for IPv4/IPv6. You have 3 
bits, like the (old) IPv4 Precedence. In theory more QoS information 
could be coded in the label, of course.

> IPv6 has the "Flow label" field wich makes routing faster

again, the "faster" doesn't matter with today's ASICs in place.

> and has less header overhead than ipv4 (or mpls+ipv4)

n*4+20 vs. 40 - less overhead?

> And i think flow label could have the same use as
> the mpls label value...
>
> How is MPLS to IPv6 related?

as already answered: the same as MPLS to IPv4.
Well, there is always a difference between theory and implementation. 
MPLS needs LDP (and RSVP depending on what you do), LDP uses IP UDP and 
TCP. Although informations within are "TLV" coded and thus expandable I 
haven't seen any IPv6-based LDP on my Cisco so far. Read: you may have 
IPv4 to run protocols like LDP to finally run MPLS carrying IPv6 
packets.

> Are they technologies that have nothing to do with each other?

 From a generic point of view: correct.

> Or MPLS can bring new functionalities to IPv6 networks (like to IPv4), 
> and
> so mpls+ipv6 would have a sense?

exactly. Hope I don't start a religious war now but look upon IPv6 as 
an IPv4 with larger addresses, a more structured approach to "ip 
options", avoiding fragmentation (on transit routers) and such. In 
short: more addresses ;-)

> And if so, what are the benefits?

Same as for IPv4: TE capabilities, allows you to integrate ATM into 
your IP packet network, [...].

> IPv6 has all what mpls+ipv4 has (separeted flows to support qos
> VPNs faster routing) and so mpls would have no further use?

Don't see that IPv6 has any VPN support (other than IPSec which IPv4 
supports as well).


Regards, Marc
--
Marc Binderberger    <marc@sniff.de>    Powered by *BSD ;-)


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