WS-X6148A-GE-TX performance question

Are the X6148A cards dedicated 1 gb/s uplink for each port ( shared 32 Gb/s
bus , as long as each port is it's own 1 gb/s still to the 32gb/s bus and
not shared with 7 other ports, so effectively just 125Mb/s per port then if
all used at full/even capacity) ?

I can't really find anything much on X6148A internal architecture online,
but it would seem that each port gets its own 1gb/s link to the
card/backplane, and that the bottleneck then is the 32gb/s backplane (which
is fine, as long as it's not 1 gb/s per each set of 8 ports!).

Best regards,

Scott Spencer
Data Center Asset Recovery/Remarketing Manager
Duane Whitlow & Co. Inc.
Nationwide Toll Free: 800.977.7473. Direct: 972.865.1395 Fax: 972.931.3340
Sales of new and used Cisco/Juniper/F5/Foundry/Brocade/Sun/IBM/Dell/Liebert
and more ~

There was a good thread on Cisco-nsp regarding this exact subject recently.
My recollection is that both X6148 and X6148A have just 6 1GB ASICs.
Therefore the over subscription rate is 8:1. The biggest difference between
these LC's is that X6148A will support large MTU whereas X6148 will not.


Scott Spencer wrote:

the other difference between WS-X6148-GE-TX and WS-X6148A-GE-TX is the A
has better QoS queuing potential (more hardware queues available) and a
lower list price...

As I recall, there are 6 ethernet controllers with 8 ports on each...
(8:1 oversubscription among the adjacent ports in a port group which use
the same ethernet controller).

The card is a Classic card, so the whole card is limited to 32 Gbps to
the backplane, which given the oversubscription ratio, shouldn't be much
of an issue...

Cisco recommends both cards for access-layer use, principally as wiring
closet aggregation for desktop users. Cisco recommends 65xx or 67xx line
cards for backbone (read deterministic) connections, which means that
only 65xx devices with sup720s, or older switch fabric modules can be
used for deterministic network design.

Note that Etherchannel limitations apply to both cards. Also running one
port in a group of 8 at line rate ( for example using that port as a
SPAN destination for a VLAN where traffic exceeds 1 Gbps) will cause
drops on the other ports in the group.

0080094714.shtml )

Sadly, it is 1Gb per each set of 8 ports. The WS-X6148-GE-TX line card has its uses, just not in the data center. To recap on the thread a couple of weeks ago:

- no storm control
- no port security
- 1G aggregate traffic for each group of 8 ports (i.e. think of it as 6 x gigabit ethernet hubs with shared input buffers connected into a 32G backplane)
- 2 ports per etherchannel

It's not a service provider blade and doesn't belong in a data center switch setup. Don't be disappointed by this: it was designed to be an aggregation blade for enterprise desktop usage and is quite useful in that context.