[j-nsp] Upgrade from M10i?

[ken lindahl]

well, i certainly got my money's worth from that p.s. :-)
thanks to Richard, Stacy, Kevin, and others who have contributed
valuable information to this thread.

ken

On 2/4/2009 9:31 AM, Richard A Steenbergen wrote:
> On Wed, Feb 04, 2009 at 08:17:12AM -0800, ken lindahl wrote:
>> p.s.: it's worth noting that adding "tunnel PIC capability" to an MX, in 
>> order to have it act as an RP, uses a full slot in the chassis.
> 
> Not exactly... At worst you disable a full "pic" (1/4th of the DPC card) 
> to create a tunnel, at best you don't have to disable anything at all 
> (for a 1G tunnel).
> 
> If you look at the architecture of the MX, basically what Juniper did
> was to use a large number of distributed 10G packet forwarding engines
> (PFEs) functioning in parallel rather than a smaller number of faster
> (but more expensive) PFEs, to create a platform that is optimized for
> doing 1/10GE. Each DPC is actually 4 individual PFEs, each with its own
> I-chip, controlling either one 10GE port or a group of 10x1GE ports. 
> These appear as "PICs" within JUNOS (even though they aren't physically
> remoevable), but unlike traditional pics which contain only interface
> components (not routing components), each "PIC" functions as its own
> PFE.
> 
> When you go to create a "tunnel pic" interface, what you're actually
> doing is stealing some PFE capacity for use on your tunnel service. 
> Since the MX doesn't use pluggable cards, there is no physical tunnel 
> "PIC", it's just a softward controlled loopback. Remember that the 
> tunnel "PIC" on other platforms doesn't actually do anything other than 
> create a physical loopback and identify itself to the chassis (there is 
> about $10 worth of electronics on one :P), what it's actually doing is 
> taking some PFE capacity by blocking off those PIC slots.
> 
> On the MX you have the option of creating either a 1G or 10G tunnel, 
> though currently you don't have a choice in the matter because you are 
> restricted to using 1G or 10G based on the type of card ("PIC" PFE 
> actually) inserted. If the PFE is controlling a 10GE port, you can only 
> create a 10G tunnel port, which disables the physical 10GE port. If the 
> PFE is controlling 10x1GE, you can only create a 1G tunnel port. Now the 
> interesting thing is that each PFE is actually capable of doing 11Gbps, 
> so when you create a 1G tunnel port on a 10x1GE PFE it doesn't actually 
> disable any of the existing ports it just creates a "pic 10" interface. 
> The rumor mill has it that the 10GE PICs are capable of doing this too, 
> and at some point in the future the software will support creating a 1G 
> tunnel on a 10GE PFE without disabling the physical interface.
> 
> The same rules apply to the newer mixed cards (2x10GE + 20xSFP) and 
> limited cards (2x10GE only), each "PIC" is still either a 1x10GE or 
> 10x1GE, all they're doing is mixing and matching the types onto 
> different cards to satisfy configuration requirements without needing to 
> make the interfaces swappable.
>