Bus is _shared_, with CFEB you have guaranteed 3.2Gbit shared by up to 4 PICs, with E-CFEB is non issue single PIC limit is 1G and E-CFEB will do full 1G per no matter what.
If you try to handle more than 3.2Gbit on a CFEB bus (X-0/X/X or X-1/X/X) you may see bus contention depending on packet size. Load 4xGE and maybe. Load 3xGE + 4xDS3 is pushing limit but OK. With E-CFEB, non issue. With CFEB summ the bandwith make make sure is 3200Mbit or less, and 3200 is shared by all 4 PICs. On 2/23/13 6:51 PM, Matt Bentley wrote: > Thanks! So it would be correct to say you should NEVER see > oversubscription on a channelized DS3 card right? Obviously, you can > overdrive a single T1, but you'd never see drops due to the PIC itself? > I guess what I'm asking is whether or not the bandwidth availalble on a > FPC is allocated equally per PIC, or if everyone sort of shares it. > > On Sat, Feb 23, 2013 at 8:13 PM, Christopher E. Brown > <chris.br...@acsalaska.net <mailto:chris.br...@acsalaska.net>> wrote: > > > With the std cfeb after internal overhead per bus capacity is 3.2Gbit of > traffic, this is worst case minimum small packets, etc. > > Raw bus capacity is IIRC ~ 4Gbit, difference is overhead. > > Unless you are doing all small packet, actual limit is higher than 3.2. > > Enhanced CFEB bumps the raw bus capacity to something around 5Gbit, and > the after all overheads forwarding capacity to 4Gbit (based on the 1G > per PIC limit). > > Summ... > > CFEB > Up to 1Gbit per PIC, 3.2Gbit per bus _worst case small packet_ > > E-CFEB > Up to 1Gbit per PIC > > > These figures are > On 2/23/13 6:01 PM, Matt Bentley wrote: > > OK - so there has been a lot of discussion around this that I've > seen, but > > I've searched for hours and still can't find concrete answers. > Can someone > > help? > > > > 1. Does the 3.2 Gbps throughput limitation include overhead? In > other > > words, Is the "raw" throughput 4 Gbps with effective throughput of 3.2 > > Gbps? Or is it 3.2 Gbps of raw throughput with effective > throughput of 2.5 > > Gbps? > > 2. Is this throughput per PIC on the FPC? So let's say I have > three 4x > > GigE IQ2 PICs and one channelized DS3 IQ PIC. Does each PIC get > bandwidth > > allocated equally between them? So is it 800 Mbps per PIC, and > the PICs > > can't "steal" bandwidth from another one? > > 3. Where, and based on what, is traffic dropped with Juniper > head of line > > blocking (ie where multiple high speed input interfaces try to go > out the > > same lower speed exit interface)? > > > > Thanks very much! > > _______________________________________________ > > juniper-nsp mailing list juniper-nsp@puck.nether.net > <mailto:juniper-nsp@puck.nether.net> > > https://puck.nether.net/mailman/listinfo/juniper-nsp > > > > > -- > ------------------------------------------------------------------------ > Christopher E. Brown <chris.br...@acsalaska.net > <mailto:chris.br...@acsalaska.net>> desk (907) 550-8393 > <tel:%28907%29%20550-8393> > cell (907) > 632-8492 <tel:%28907%29%20632-8492> > IP Engineer - ACS > ------------------------------------------------------------------------ > _______________________________________________ > juniper-nsp mailing list juniper-nsp@puck.nether.net > <mailto:juniper-nsp@puck.nether.net> > https://puck.nether.net/mailman/listinfo/juniper-nsp > > -- ------------------------------------------------------------------------ Christopher E. Brown <chris.br...@acsalaska.net> desk (907) 550-8393 cell (907) 632-8492 IP Engineer - ACS ------------------------------------------------------------------------ _______________________________________________ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp