[ILUG] Naive ADSL/WiFi questions (long (sorry!))?

[paul at clubi.ie]

On Mon, 25 Jun 2007, Thomas Bridge wrote:

> not shudder - it's part of how it works.   And why you have to be
> careful parsing the output of traceroutes over an MPLS network.

Right, that's shuddersome.

> It doesn't POP "on behalf of" - it POPs the label to forward the 
> encapusalted MPLS packet / IP packet / whatever it is so that the 
> final device doesn't need to do two lookups.

Right.. on behalf of. It's an optimisation.

>> MPLS.. shudder.
>
> Another example of why Paul is right and the rest of the world is wrong? :)

You're saying that building layers of networks through tunneling, 
with each layer running independent routing, is a good thing? There 
are genuine problems in IP that MPLS addresses, it's just MPLS 
addresses them in a way that sucks architecturally.

MPLS "fixes":

- desire to be able to route multiple IP address spaces, which comes
   about in large part because of the lack of public space
- hardware guys aversion to parsing IP (not fixed length, has options
   that might need to be parsed, no fixed-length network versus host
   identifiers to make hardware lookups cheaper to implement)
- The administrative overheads of IPv4
   (must configure public address per link for routing)
- lack of funky ways to route IP
   - this one isn't really valid, can be implemented for IP..

IPv6 should have fixed the first three, but sadly it's a curiosity 
and will remain so until IPv4 melts down (if ever). IPv6 doesnt fix 
the second, the hardware people seem to be quite bitter about that... 
It sort of fixes the third, with link-locals.

These aren't my opinions really...

regards,
-- 
Paul Jakma	paul at clubi.ie	paul at jakma.org	Key ID: 64A2FF6A
Fortune:
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