On Tue, Jan 29, 2008 at 09:22:53AM +0100, Marian ??urkovi?? wrote: > On Mon, Jan 28, 2008 at 11:07:13PM -0500, David Prall wrote: > > It uses SFP+'s, they supposedly will be available in both 1GE and 10GE. > > While the move to SFP+ for the Nexus7000 is clearly the only solution > (datacenter needs high density & low cost 10GE links and Nexus has > the potential for 500 Gbps per slot), the SFP+ datasheet says it will > also be adopted in Cat6000/4000/3000 series. > > Could someone please explain the motivation for this? > > >From the customer's perspective, it's a nightmare to see fourth different > 10GE form factor coming into e.g. Cat6500, especially when XFPs were > already used on 10GE SPAs and ES20 cards. Consolidation on XFP form > factor would be IMHO much better for several reasons: > > - it's also XFI-based > - all types are available *now* (including CX4, ZR and DWDM which are not > planned for SFP+) > - supports both LAN and WAN PHY > - offers sufficient port density (24) for 80 Gbps per slot backplane > - has the widest adoption rate as it's used in SONET/SDH, DWDM and ethernet > equipment > - is subject to continuos inovation (tunable XFPs, ultra long reach XFPs > etc.)
Don't forget, SFP+ is limited to such low power (1.5W in the highest power class) that it is all but impossible to ever power long reach optics (40km or 80km+) with them. The motivating factor behind SFP+ is the ability to do high port density and crazy oversubscription, since SFP+ is so much lower power than XFP. Note that if you compare the same types of optics (i.e. SR to SR, LR to LR), the power difference between SFP+ and XFP is minimal (yes you're offloading a CDR component, but you're just moving it off to the host board so in the end you stay pretty neutral). The difference is that SFP+ has no higher power classes (2.5W or 3.5W as in the case of XFP long reach), therefore it will never be possible to put a long reach optic in one, therefore you can "safely" design a 36 or 48 port card for them. This is fine if all you're doing is datacenter or small campus stuff, but completely destroys the capability to do long reach/DWDM optics over dark fiber. Personally I suspect that SFP+ is not going to be particularly popular with the SP crowd, and any vendor who values their business should make a high-density (16-port or so) XFP blade alternative as well. -- Richard A Steenbergen <[EMAIL PROTECTED]> http://www.e-gerbil.net/ras GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC) _______________________________________________ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/