08-10-2017 02:43 PM - edited 03-08-2019 11:42 AM
Hoping someone can clear this up for me. A co-worker had a TAC case a long while back for some discards we were seeing on some ports. He had documented that TAC told him on this card, groups of 8 ports share 1gbps. I have searched for information regarding this, but haven't found anything. Anyone know if that is true, and why exactly that is? is it the same case for a WS-X6748-GE-TX with WS-F6700-DFC3B ?
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08-11-2017 05:01 AM
Different 6500 line cards do have different architectures regarding bandwidth to/from line ports. Very possible one of the older line cards, especially one for "users", rather that for "servers", had 8 Gbps shared between 8 gig ports, but as Reza notes, a 6748 should have 20 Gbps shared between 24 ports. (NB: I believe Reza might be mistaken about all 67xx cards have dual 20 Gbps fabric connections. I recall the 6724 only has a single 20 Gbps connection.)
If you're also wondering about the impact of a CFC vs. DFC equipped 6700 line cards, it shouldn't make any difference to raw bandwidth capacity of the card, itself, but it can impact actual bandwidth capacity to/from the card as CFC cards all share the sup's capacity for forwarding while the DFC equipped cards perform forwarding locally on the card. Additionally, what else is in the chassis impacts bandwidth capacity. For example, a chassis with only 6500 fabric cards, allows double the MPPS rate on a sup720 and the MPPS rate is not impacted by frame size. Conversely a 6700 line card passing data to/from a classic bus card might be limited by the bus bandwidth capacity.
A 6500's capacity and performance can vary much depending on how it's actually populated.
08-10-2017 04:45 PM
Not sure if that is the case but referring to the data sheet for this module, this is what it says:
WS-X6724-SFP supports a single 20-Gbps channel connection to switch fabric on Supervisor Engine 720; all other 67xx interface modules feature dual 20-Gbps channel connections (40Gbps total) to the switch fabric
link to data sheet:
https://www.cisco.com/c/en/us/products/collateral/switches/catalyst-6500-series-switches/product_data_sheet0900aecd801459a7.html
HTH
08-11-2017 05:11 AM
Good link, thank you
08-11-2017 05:01 AM
Different 6500 line cards do have different architectures regarding bandwidth to/from line ports. Very possible one of the older line cards, especially one for "users", rather that for "servers", had 8 Gbps shared between 8 gig ports, but as Reza notes, a 6748 should have 20 Gbps shared between 24 ports. (NB: I believe Reza might be mistaken about all 67xx cards have dual 20 Gbps fabric connections. I recall the 6724 only has a single 20 Gbps connection.)
If you're also wondering about the impact of a CFC vs. DFC equipped 6700 line cards, it shouldn't make any difference to raw bandwidth capacity of the card, itself, but it can impact actual bandwidth capacity to/from the card as CFC cards all share the sup's capacity for forwarding while the DFC equipped cards perform forwarding locally on the card. Additionally, what else is in the chassis impacts bandwidth capacity. For example, a chassis with only 6500 fabric cards, allows double the MPPS rate on a sup720 and the MPPS rate is not impacted by frame size. Conversely a 6700 line card passing data to/from a classic bus card might be limited by the bus bandwidth capacity.
A 6500's capacity and performance can vary much depending on how it's actually populated.
08-11-2017 05:10 AM
Thanks, good info. I'm going to have them try to dig up notes on what TAC told them, or maybe just contact then again for clarification. It sounds like "8 ports share 1 gb" can't possibly be correct, so I'm guessing someone mis understood something somewhere,
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