[116886] in North American Network Operators' Group
Re: Alternatives to storm-control on Cat 6509.
daemon@ATHENA.MIT.EDU (Mike Bartz)
Tue Aug 25 16:22:40 2009
In-Reply-To: <4A92FF4F.9000109@foobar.org>
Date: Tue, 25 Aug 2009 16:21:42 -0400
From: Mike Bartz <mob@bartzfamily.net>
To: Nick Hilliard <nick@foobar.org>
Cc: nanog@nanog.org, Peter George <Peter.George@lumison.net>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Mon, Aug 24, 2009 at 4:59 PM, Nick Hilliard <nick@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
mob@bartzfamily.net
