[c-nsp] 6500/7600 TCAM Usage

Patrick M. Hausen hausen at punkt.de
Fri Jun 3 07:14:17 EDT 2016

Hi, Saku,

> Am 03.06.2016 um 09:10 schrieb Saku Ytti <saku at ytti.fi>:
> Not all platforms use TCAMs. Lot of Juniper kit, like MX, QFX10k, PTX
> use various types of DRAM solution, this makes FIB usually not your
> bottleneck, search time to larger database becomes an issue too.
> Most SP scale routers, MX, ASR9k, ALU^H^H^HNokia SR, Huawei NE etc can
> hit several million in FIB.

Ah ... thanks.

>> With RIRs handing out ever smaller prefixes I expect
>> the IPv4 address space fragmentation to accelerate.
> RIRs are mostly handing static prefix sizes now, not ever smaller. But
> they are smaller than historically.

Sorry, but that's just semantics, IMHO. When we startet to apply as
a new LIR, the then current allocation from RIPE was /19. When we
finished the process we got a /20. Today they are handing out
/22. I'd call that "ever smaller".

Trading of IPv4 addresses will further increase the number of
/24s in the DFZ. Or smaller, even - people come up with gross
hacks all the time.

>> I did not yet take the time to browse individual datasheets
>> of gear that is supposedly "bigger" than a 65k.
>> Some pointers would be most welcome.
> You're asking what platform you should buy? Usually people pay
> thousands of dollars to consultants to figure that out.

No. Just some pointers to one platform or another that tackles
the above problem. As I said I did spend time to search, unsuccessfully,

E.g. after Gerd's answer I looked up the ASR9k family from Cisco. I cannot
find that 4M routes figure anywhere in the datasheets.

> Without knowing your specs, I'd buy ALU SR, JNPR PTX or JNPR MX.

:-) Of course. No, no free consulting required here. I stil have some time
to give some homework to various vendors. Besides, our supplier for
secondary market Cisco gear is quite knowledgeable, too. And not
limited to Cisco.

I'm really interested in how vendors address the problem of fixed TCAMs in
a general way, because any fixed size will be too small, eventually.

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