On Mon, Aug 24, 2009 at 4:59 PM, Nick Hilliard n...@foobar.org wrote:
On 24/08/2009 19:03, Holmes,David A wrote:
Additionally, and perhaps most significantly for deterministic network
design, the copper cards share input hardware buffers for every 8 ports.
Running one port of the 8 at wire speed will cause input drops on the
other 7 ports. Also, the cards connect to the older 32 Gbps shared bus.
IMO, a more serious problem with the 6148tx and 6548tx cards is the
internal architecture, which is effectively six internal managed gigabit
ethernet hubs (i.e. shared bus) with a 1M buffer per hub, and each hub
connected with a single 1G uplink to a 32 gig backplane. Ref:
http://www.cisco.com/en/US/products/hw/switches/ps700/products_tech_note09186a00801751d7.shtml#ASIC
In Cisco's own words: These line cards are oversubscription cards that are
designed to extend gigabit to the desktop and might not be ideal for server
farm connectivity. In other words, these cards are fine in their place,
but they are not designed or suitable for data centre usage.
I don't want to sound like I'm damning this card beyond redemption - it has
a useful place in this world - but at the expense of reliability,
manageability and configuration control, you will get useful features
(including broadcast/unicast flood control) and in many situations very
significantly better performance from a recent SRW 48-port linksys gig
switch than from one of these cards.
Nick
We experienced the joy of using the X6148 cards with a SAN/ESX cluster.
Lots of performance issues! A fairly inexpensive solution was to switch to
the X6148A card instead, which does not suffer the the 8:1
oversubscription. It also supports MTU's larger than 1500, which was
another shortcoming of the older card.
Mike
--
Mike Bartz
m...@bartzfamily.net
