6500 features

[suthomas1]

Hi,

I have few queries on 6500 switches. I'd try searching, but didn't get an easily comprehensible answer from my understanding point.

1. What is so the called MSFC,PFC,DFC & its functions/importance.

2. On a 6500 image, we come across /s72033 as start string for IOS image. I reckon 720 should be indicating Supervisor engine, how about the remaining digits?

3. what is the difference between different supervisor family like Sup 720 & 720-3B, Sup32 etc. Is there any link which differentiates them?

4. what is bootstrap that we see when switch boots up.

5. what is sync command used for in IOS parlance during rom monitor mode.

Thanks.

[Reza Sharifi]

Hi,

MSFC is a daughter card that sits on the Sup module.  It is the layer-3 card that provide routing functionality.

As for the difference between Sup-720-3B, 3C, 3CXL, etc....  Refer to this document.

http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps708/product_data_sheet09186a0080159856_ps4835_Products_Data_Sheet.html

HTH

Reza

[Yogesh Ramdoss]

Hello,

PFC. DFC and CFC FAQs:

http://www.cisco.com/en/US/products/hw/switches/ps708/products_qanda_item09186a00809a7673.shtml

Image name: s72033

S720 stands for Sup720. 33 stands for PFC3 and MSFC3.

Sup720 Datasheet lists difference between different DFCs:

http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps708/product_data_sheet09186a0080159856.html

Bootstrap (or Boot) image is a subset of an IOS image, with limited capabilities. It helps to restore when an IOS image is accidentaly deleted or corrupted.

SYNC command is llike "save' command for ROMMON. When you set a ROMMON variable, sync command is recommended to take effect.

Yogesh

[Mohamed Sobair]

Hello,

The PFC3 is the ASIC-based forwarding engine daughtercard for the       Sup720; the DFC3 is the ASIC-based forwarding engine daughtercard for various       fabric-enabled linecards.  The MSFC is alayer-3 card in th supervisor engine that responsible for all layer-3 functions.

The main difference between Sup720 and Sup32 is that, Sup720 provides up to 400 Mpps throughput where as Sup32 provides up to 15 Mpps throughput, So the difference primarily on the terms of bandwidth it can support also per line card.

Another big advantage of Sup720 is that it supports Distributed CEF to all line cards So the all line cards distributed the CEF table locally independantly from the Sup after its got poulated , this is not the case with Sup32.

HTH

Mohamed

[Jon Marshall · Accepted solution]

1) On a L3 switch there is a split between -

a) the control plane - this is responsible for handling the L2 control protocols eg. STP/CDP/PagP etc. and the L3 control protocols ie. the routing protocol EIGRP/OSPF etc. The control plane uses the routing protocol to establish neighborships/peerings with other L3 devices and exchanging routing information. 

b) the forwarding plane - this is responsible for forwarding both the L2 and L3 data

The MSFC handles the control plane in a 6500. The PFC handles the forwarding plane on the 6500. Both cards are integrated into the supervisor. The PFC downloads the forwarding table from the MSFC.

The 6500 can also act in CFC or DFC mode per linecard -

CFC is Centralised Forwarding and this means when a packet is received by a linecard a part of the packet must be sent to the supervisor for a forwarding decision to be made.

DFC is Distributed Forwarding and this means that linecard does not have to send any part of the packet to the supervisor because it can make it's own forwarding decision. This can have a dramatic effect on performance ie.

CFC forwarding is up to 30Mpps, DFC forwarding can reach 400Mpps.

2) s72033. As far as i know it is sup720, PFC3, MSFC3

3) See Reza's link.

** Edit - the big difference between the Sup32 and the Sup720 is that the Sup32 only supports connections for the linecards to a shared 32Gbps bus so all linecards in the chassis have to share that bus. The Sup720 can provide up to 40Gbps per linecard slot and this 40Gbps is dedicated per linecard.  It's important to note that there are certain linecards that cannot work with a Sup32 eg. the fabric only linecards such as the 67xx/68xx modules.

4) the bootstrap is a small program that is initially loaded when the switch boots up. It generally has enough "smarts" to locate and load the main IOS image.

5) Not sure what you mean. Generally the IOS sync is used to sync the image between supervisors when you have redundant supervisors in the same chassis.

Jon