Difference in these two line cards?

[jwbensley]

I am compairing two line cards for use in a 7609-S chassis. I am have been looking at this page, amoungst others: http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps708/prod_end-of-life_notice0900aecd8069af87.html

There is a 48x 10/100 card, WS-X6348-RJ-45, it has the following credentials;

Backplane Connection: 32 Gbps Bus

Forwarding: Centralized

This is also a 48x 10/100 card, WS-X6548-RJ-45, it has the following credentials;

Backplane Connection: Switch Fabric and Bus

Forwarding: Centralized - Supports optional DFC card

I would like to understand the different between these two cards. Since the 7609-S has a 720Gbps backplane, what kind of switch fabric connection does the WS-X6348-RJ-45 make with the chassis? Does it have 2x8Gbps connections or 2x20Gbps connections? I assume 2x8Gbps connections as 2x20Gbps connections are for cards supporting dCEF, is this correct?

Also, does the WS-X6548-RJ-45 have 2x8Gbps fabric connections unless a dCEF card is installed?

Many thanks.

[Joseph W. Doherty · Accepted solution]

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Posting

Since the 7609-S has a 720Gbps backplane, what kind of switch fabric connection does the WS-X6348-RJ-45 make with the chassis? Does it have 2x8Gbps connections or 2x20Gbps connections? I assume 2x8Gbps connections as 2x20Gbps connections are for cards supporting dCEF, is this correct?
Also, does the WS-X6548-RJ-45 have 2x8Gbps fabric connections unless a dCEF card is installed?

The 7609-S supports a 720 Gbps fabric, it doesn't actually supply it.  The 720 Gbps is dependent on having a sup720 (vs. a sup32).

The WS-X6348-RJ-45 is a "classic bus" card and only connects to the 32 Gbps shared bus.

Fabric connections are only available on CEF256 (1 or 2 eight Gbps connections) or CEF720 (1 or 2 twenty Gbps connections) line cards.  CEF256 line cards with just a single eight Gbps fabric connection (which are most) also have a 32 Gbps shared bus connection.

dCEF cards support the DFC (usually optional; although not supported on some CEF256 cards) that allows for local forwarding (i.e. it doesn't need to use the main sup).

The WS-X6548-RF-45 only has a single (32 Gbps shared bus and) eight Gbps fabric connection (i.e. DFC doesn't change that).

The two big differences between these two cards, the 6548-RJ-45 supports a fabric connection and dCEF which the 6348-RJ-45 does not.

Is this important differences?  Depends on your supervisor and your traffic usage on the platform.  For example, if you had a sup32, you wouldn't be able to use the fabric or dCEF capabilities of the 6548-RJ-45.  If you had a sup720, you could use the additional capabilities of the 6548-RJ-45, but then there's the question, do you need to?  (I.e. any real benefit?)  NB: there are some "gotchas" when mixing various line card types in the same chassis; not too many of the "it won't work" type, but of the "it's not optimal" type.)

[jwbensley]

Thanks for your response Joseph Doherty. This has cleared some things up for me and given me more info to read about. Thank you

[Leo Laohoo]

To top of Joseph's comment, I have one bit of question:  What are you trying to do?

I mean I've never used a 7600 before but sticking a 6348 and/or 6548 line card in a 7600 is kinda bit "wierd".  I hope you are not trying to connect SERVERS into either one of these blades because it won't "work".

The 6148, 6348 and 6548 are line cards designed as an access switch.  It ain't designed for high-speed server connection.  You want to connect servers?  Then you should be looking at the 6748 as this line card is exclusively for server access port (hence you can't find a 6748 with PoE).

[jwbensley]

HI Leo,

I'm trying to document some spare lines cards I have. I have a further question now though about all these lines cards being mentioned;

Since the WS-X6348-RJ-45 has a classic bus connection to the shared 32Gbps fabric, what speed is that classic bus as I assume this is going to determine to maximum throughbut of this card. Is that correct?

I assume as it doesn't support dCEF it has to talk back to the SUP/RSP for all traffic, even between to ports on the same line card, so a WS-X6348-RJ-45 with 48x 100Mbps connections on it totals to 4,800Mbps. Can this much traffic be pushed from all the ports on this card to say 48x 100Mbps ports on another card  in another slot? Also, what about 24 ports on this card to the other 24 ports on this card?

How does the fabric connection here limit the speed of the card and how does this compare with the WS-X6548-RJ-45?

(I'm working my way upto WS-x67xx cards).

Many thanks guys,

James.

[Joseph W. Doherty]

Disclaimer

The  Author of this posting offers the information contained within this  posting without consideration and with the reader's understanding that  there's no implied or expressed suitability or fitness for any purpose.  Information provided is for informational purposes only and should not  be construed as rendering professional advice of any kind. Usage of this  posting's information is solely at reader's own risk.

Liability Disclaimer

In  no event shall Author be liable for any damages whatsoever (including,  without limitation, damages for loss of use, data or profit) arising out  of the use or inability to use the posting's information even if Author  has been advised of the possibility of such damage.

Posting

If you understand shared (non-switched) Ethernet, think of each classic bus line card as a host connected to 16 Gbps duplex shared Ethnernet link.  This then limits the maximum transmission rate between cards to 16 Gbps (in one direction).  This bandwidth is shared among all the line cards.

If you had a sup32-10ge the whole chassis couldn't drive the two 10 gig uplinks to full capacity nor accept traffic from them at full (both) link capacity.

If using 10/100 line cards, unlikely the bus capacity will be much of an issue.  If using gig line cards, the bus might be a bottleneck (as well might the 15 Mpps forwarding capacity of most 6500 sups).

PS:

If you understand switched Ethernet, think of each fabric line card as a host with a link or two links to a switch port of either 8 Gbps or 20 Gbps.

[jwbensley]

Hi Joseph,

Thanks for clearing that up.

I understand this part; "If you understand switched Ethernet, think of each fabric line card as a host with a link or two links to a switch port of either 8 Gbps or 20 Gbps."

Isn't this only true of CEF256 and CEF720 cards? A WS-X6348-RJ-45 isn't a CEF256 of CEF720 card, so it connects to the shared 32Gbps shared fabric, but at what speed? What speed bus connection do non-CEF256 and non-CEF720 cards have?

This doesn't seem to be easily accessible documentation on Cisco's site.

Many thanks,

James.

[Joseph W. Doherty]

Disclaimer

The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

Non-fabric connection, i.e. shared bus, is a 16 Gbps (duplex) connection.  All line cards in the chassis, with this connection share it.