[c-nsp] ASR 1002-X FIB scalability

[Pete Lumbis]

> According to my "research" so far, the ASR1k does use TCAM but *not*
> for the actual FIB. It's used for ACLs and QoS stuff, though.


You are 100% correct. TCAM for features, QFP memory for FIB.

It would mean we utilize just 40% of the QFP DRAM for that kind of FIB and
> the box is apparently more limited by the RP/ESP RAM than by QFP RAM
> (the QFP part is specced identical or better then ESP40 at 1GB QFP RAM,
> 40MB TCAM and 512MB packet buffer), which explains why the real ESP40
> with dedicated 8GB of FECP RAM can be specced for 4M routes in the FIB,
> while the 1002-X reaches the roof a little earlier. But is the 3.3M
> prefixes FIB really condensed to those 316MB of PLU Mgr stuff (and what
> does PLU stand for)?
>

Yeah, it condenses way down. I'm not sure exactly what the magic is, but
I'm sure it has to do with only storing a prefix and next hop adjacency
instead of additional information about the route itself.

The PLU is "Pointer Lookup Unit". Also know as the forwarding lookup
process.