[j-nsp] System board memory expansion on M7i

[Nicolaj Kamensek]

Rubens Kuhl Jr. schrieb:

> 550k IPv4 routes, I guess... so if all IPv4 prefixes get an IPv6
> counterpart which has a prefix size twice as IPv4's, that would map to
> a 183k (IPv4 + IPv6) routes. Hummmmmmm...

~550k ipv4 routes with just 8mb sram, yes. We tried it here in the lab 
with several routing-instances on M20 /w SSB-E and SSB-E16(16MB SRAM, 
256MB DRAM):

* SSB-E: ~550.00 routes -> heap 99%, ssb crashes
* SSB-E16: > 1.000.000 routes -> heap > 95%, ssb reached it's limit

But e.g. with the old SSB-E you might not even reach those 550.000 
routes anyway in a real world scenario because of the small amount of 
DRAM with just 64MB that stores arp-entries, the copy of the SRAM and so 
on..

> Even on a Internet Exchange where there few ARP entries ? A cable
> scenario would use thousands of ARP entries... or there are any other
> reasons for having 256M on the FEB ?

In our case: we need > 64MB of DRAM in our M20 routers because we ran 
into limits with about 7500 arp entries. So we bought the SSB-E16 and 
are doing fine with currently 8500 arp entries. Heap usage dropped from 
85% to 23%.

Regards,
Nico


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