[c-nsp] Cisco 10G gear

Simon Lockhart simon at slimey.org
Sat Jan 17 04:36:09 EST 2015

On Sat Jan 17, 2015 at 10:53:01AM +0200, Chris Knipe wrote:
> I'm still confused :-( Sorry.  The only other line card in the chassis
> would be one WS-X6748-GE-TX which is a 48 Port 10/100/1000 card.

With 6704 and 6748-GE-TX you'll be in CEF720 switching mode, not classic.
This will give you the full 30Mpps switching with CFC's.
> Yes, the SUP720 comes with MSFC3/PFC3 standard (we will be upgrading
> memory on the SUP as well as the MFC to 1G, the max supported), and it
> states it can deliver up to 40Gbps per slot.  But from what you've
> mentioned, we will thus now be limited to 15Mpps which is clearly not
> going to be enough.

If you're only doing layer 2 switching and no routing, then you shouldn't
need to upgrade the RAM - this is used more for route storage (RIB).

> The SUP720-3B is perhaps also an option, but if I have to start
> looking at the 720-3BXL then it's becoming very expensive, yet again.

Consider looking at refurb / 2nd-user - either official Cisco refurb 
or 3rd party. You'll probably be pleasantly surprised by the pricing.

> Do I then also understand correctly that in the case of a SUP720-3B I
> need to purchase a WS-X6708-10G-3C and in the case of a SUP720-3BXL we
> are talking about a WS-X6708-10G-3CXL (there are no 4-port line card
> available with a DFC daughter card), or are these special versions
> with the daughter cards only required to lower the impact of the
> contention on the 8-port cards?

The 6708 is an odd card - it has the DFC 'soldered in', so it's not field
replaceable/upgradeable. The difference between 3B and 3BXL is purely the
number of layer 3 routes it can hold in the FIB. If you're only doing L2, 
then this won't give you any benefits.

> Would the same also hold true then on a SUP720-3B or SUP720-3BXL in
> the case of a WS-X6704-10GE, or would the bigger (better) SUP have no
> problem with smashing the 15/30Mpps to pieces and deliver true 10Gbps
> per port?  I'm not after 100% guaranteed 10Gbps per port on the line
> card, but I most certainly don't want to spend all this money and only
> get like ~3Gbps per port either.

You won't get true line rate on all 4 ports on a 6704. They're well known as
having performance issues due to underpowered ASICs. We've been seeing about 
25-30Gbps of aggregate traffic (general internet traffic, adding in+out on
all ports) before they run out of steam.

> What other options (except Nexus) would there be that can deliver ~8 x
> 10GE (fiber) and 48 x 1GE at an affordable rate?

Depends on your total traffic requirements. SUP720 + 6704 + 6748-GE-TX
(+ 6724-SFP if I need fibre) is still my work-horse of choice for a Cisco
switch offering both 10G and 1G ports. On the used market, these blades are
available very cheaply.

>  Nexus is WAY over my
> budget (and the reason why we're looking at the 6500 instead), and it
> would seem (to me at least) I am stuck between a rock and a hard place
> in terms of acquiring a low port density 10G switch at an affordable
> price.

Although I don't use it myself (as I use Extreme X460 switches for this
purpose), you may find something in the Nexus 3000 range which fits your

> Sorry for all the questions, in my 15 odd years of networking, this is
> the first time that I will be entering the 10GE arena, so I really
> want to just make sure that I get the correct kit from the start.
> These toys aren't cheap :-(

Wait until you want 40G or 100G - then you'll realise that 10G stuff is
cheap :)

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