QOS or more bandwidth

Tue May 29 17:16:22 UTC 2001

"E.B. Dreger" <eddy+public+spam at noc.everquick.net> asks:
| Although I generally agree, how does one keep QoS out of the core 
| for CBR and jitter-sensitive applications?

	Modern GigE/10GigE, properly implemented and deployed, 
can provide more than adequately low jitter for voice use.

	The ATM folks have their heads in the sand about this in 
a huge way.  Ethernet is generally cheaper than SONET.  However, 
modern WDM systems all have SONET interfaces and only some have 
GigE interfaces -- so for WAN use SONET might still be the better 
choice.  In the LAN/MAN, GigE is a lot more cost effective approach, 
speaking as someone who helped deploy a whole bunch of GigE-based 
MANs in North America.

	For folks who want extra fancy QoS mechanisms, for whatever
reason, some GigE vendors implement DiffServ in hardware with a full
8 queues/port and at least one vendor as an IP TDM approach that
is implemented in hardware.  Custom ASIC hardware matters here
because it means that enabling QoS does NOT mean reducing the box's
packets/second forwarding rate.

Ran
rja at inet.org