[j-nsp] Need suggestions..

[sthaug at nethelp.no]

> Sounds like we'll need the RE-850 if we want to take more than our 2 full feeds 
> though -- although others have said we may run out of CFEB RAM first?  Excuse 
> the newbie question, but what is the CFEB RAM used for -- we have one router 
> with one full feed and the CFEB is at 42% RAM, another with two full feeds and 
> the CFEB is at 42% also...

The CFEB memory utilization you get from "show chassis cfeb", e.g.

CFEB status:
  State                                 Online
  Intake temperature                 39 degrees C / 102 degrees F
  Exhaust temperature                46 degrees C / 114 degrees F
  CPU utilization                    11 percent
  Interrupt utilization               0 percent
  Heap utilization                   26 percent
  Buffer utilization                 27 percent
  Total CPU DRAM                    256 MB

is only part of the story. This shows the DRAM memory on the CFEB,
which is used for the operating system kernel running there, a copy
of the RIB, and some other stuff.

What is equally important is the high speed memory used for packet
pushing (static RAM for the traditional CFEB), which is a rather
small amount, and which you only see if you login to the CFEB and
use the "show jtree 0 memory" command. E.g.:

CSBR0(ar1.xxx vty)# show jtree 0 memory
Memory Statistics:
    8388608 bytes total (2 banks)
    5017384 bytes used
    3371224 bytes free
       8128 pages total
       4876 pages used
       3252 pages free
         31 max freelist size

This memory holds the FIB, nexthops and similar stuff.

Notice only *8 Megabytes* total, and about 60% of this memory in use
in the example above. If you run out of *this* memory, your box is in
real trouble.

The "plain old" M7i/M10i CFEB comes with 128 MBytes of CFEB DRAM,
which can be upgraded to 256 MBytes. 256 MBytes is mentioned as a
requirement for JunOS 9.x.

The CFEB SRAM cannot be upgraded (but you can buy a new enhanced
CFEB instead...)

Steinar Haug, Nethelp consulting, sthaug at nethelp.no