[c-nsp] Cisco 10G gear

Chris Knipe savage at savage.za.org
Sat Jan 17 04:57:21 EST 2015

On Sat, Jan 17, 2015 at 11:36 AM, Simon Lockhart <simon at slimey.org> wrote:
> On Sat Jan 17, 2015 at 10:53:01AM +0200, Chris Knipe wrote:
> 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).

Thanks for the heads up.  So we can shave a few bucks at least :-)

>> 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.

We already are ;-)

>> 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.

AHA!  Again, I didn't know this.  And the difference between the
SUP720 and the SUP720-3B?  Is that significant?  The general pricing
on the SUP720-3B is still very affordable (IMHO), but once you go to
3BXL the pricing jumps astronomically.  For us moving (if needed) from
a SUP720 to a SUP720-3B isn't going to be a show stopper.  Drastic
price drops on the 3B also thus makes sense as the routing tables more
than likely got too big for the 3B and everyone upgraded to 3BXL,
saturating the market with old 3B cards...

Time to read up on the SUP720 vs. SUP720-3B then.

> 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.

> 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.

This is what I really like (and hoped) to hear.  Considering we're
currently peaking at 1.2Gbps / 1.5Gbps, a ~10X increase in
capacity/throughput seems like a winner then.  Granted (as I
understand it), from a layer III point of view this configuration
would be significantly under spec'ed to provide what it is supposed
to, but on a layer II level it seems (to me at least) that it would be
able to deliver a -significant- upgrade to what we currently can
deliver on our infrastructure...

The 25-30Gbps you are seeing - is this across one line card, or across
the entire chassis?  Just trying to get an idea of what two or three
4-Port 10GE cards would do.

Thnx Simon, very, very helpful indeed.  Thankfully I am not in the
carrier industry, but I can just imagine how far my jaw will drop when
looking at 40GE or 100GE for that matter yes!!!


Chris Knipe

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