ra7or wrote:
Hi, recently i notice that one of our 6509 switches was operating in truncated mode when i looked at this i noticed we had an old flexwan connected to the switch that was not being used, after removing it we are now running in compact mode.
As I understand it, all non SFM will use the shared 32 Gb bus but how does having a classic card affect the sup720, what performance was lost when i had a none SFM card installed as compared to having all SFM?
thanks, Paul
Paul
Compact = centralised forwarding of up to 30Mpps
Truncated = centralised forwarding of up to 15Mpps
From the 6500 Architecture White Paper -
Compact Mode
The compact mode of operation requires a crossbar switch fabric to be present in the system. This can be provided by a switch fabric module, Switch Fabric Module 2 or a Supervisor Engine 720. All modules in the chassis must be fabric enabled (i.e. CEF256, dCEF256, or CEF720) for the switch to operate in Compact Mode. Classic line cards installed in the chassis will negate the ability of the switch to run in Compact Mode. In Compact Mode, only the header is passed over the DBus to the supervisor. The Header is compressed prior to being placed on the DBus which increases the bandwidth available for header transmission. The data portion of the packet is transmitted over the crossbar switch fabric channels. In this mode of operation, the switch can achieve centralized performance of up to 30Mpps independent of packet size.
Truncated Mode
Truncated Mode is used when CEF256 and/or CEF720 line cards are installed in a chassis with a classic line card, but a crossbar switch fabric is present. In this mode, classic line cards will transmit both the header and the data portion of the packet over the DBus. CEF256 and CEF720 line cards will only transmit headers over the DBus and transmit the data portion of the packet over the crossbar switch fabric.
Truncated mode results in centralized forwarding rates up to 15Mpps. In Truncated Mode, since the CEF256 and CEF720 line cards use the crossbar switch fabric to transmit data, overall aggregate bandwidth can actually be higher than the 32-Gbps shared bus capacity.
Performance of DFC enabled line cards are not affected by truncated mode and performance remains the same regardless of the line-card mix in the chassis.
Full link -
Jon
