We need a sup module that will support up to a 1 gig of routed traffic including GRE and BGP (full routing table). From the router performance spec sheet the sup32 supports 15Mpps (64byte packets) which equates to 7.68Gbps. Yet the cisco rep we've spoken with claims the sup32 is underpowered for our needs and suggests the Sup720 which is 2x the price. What do you folks in the field think? Thx
The Sup32 seems just fine for your needs.
Note that the Sup32, and also the Sup720 (but not the Sup720-3BXL or the RSP720), have limited hardware forwarding tables, so they don't really work with full BGP routing (>260'000 entries) today.
Another thing that the Sup32 lacks is a switching fabric. Therefore you won't be able to use line cards with it that require the switching fabric, i.e. WS-X67xx. This basically means no possibility to upgrade to 10GE interfaces (short of upgrading to a Sup32-2X10GE or Sup720 or similar).
But if you don't need any of that, you should be pretty happy with the Sup32 - it forwards IPv4, IPv6, and MPLS (including EoMPLS) in hardware. It also does GRE in hardware, provided that you use separate addresses (loopbacks) for terminating the tunnels.
Thanks Simon What routes are left out once you exceed the 256K limit? Also, is this an ASIC based limit as you can install a gig of RAM in a sup32.
If you need to do any type of QoS, a 6500 is not the right box for this. The 6500 will mark layer three traffic, but it only does layer 2 queuing, not layer 3 queuing. If you need to apply QoS on the interface, your best bet is a Metro 3750. This box has two ports that you can apply layer 3 QoS. We have a couple of WAN gig pipes and we have moved them off of our 6500's (with Sup720's) to Metro 3750's because of the need to apply QoS to the pipes. The Metro 3750 is also more reasonably priced than a sup720.
If you still want to go down the 6500 path, your Cisco rep is correct, a Sup32 is not correct supervisor for this application. The Sup32 was designed for use in a Distribution switch that needs to do some Layer 3. The issue is CPU capacity, not switching capacity. Yes the box can switch
15Mpps, but the CPU will not be able to handle the processing needs of a full BGP routing table, but your mileage may vary.
Sup 720 is fine with Qos on the right line cards (ws67xx) - as long as you dont want "hierarchical QoS" - ie shape to a rae limit and then impose QoS inside that.
the other thing to watch is the QoS is done in the hardware - so number of queues,thresholds etc depends on the I/O module.
AFAIR it has the same MSFC (layer 3 function) as a Sup 720 - the difference is about whether you use fabric and DFCs to distribute the L3 forwarding to line cards - but the "raw processing" for L3 route management is just the same...
FWIW i have seen Cat 6509s used as peering routers at 10G working pretty well.
Thankfully (we only have about 40'000 routes), I don't know. Definitely an interesting question!
The FIB (hardware forwarding table) is part of the PFC complex; I'm not sure whether it is actually physically on the ASIC (EARL?).
Anyway, RAM extension doesn't help; BGP will be able to handle many full feeds with 1GB of RAM, but - unless you route-filter pretty aggressively - the resulting FIB won't be able to fit in the hardware forwarding table on a PFC3[1]. It would fit on a PFC3XL[2], though, but that variant doesn't exist for the Sup32.
On other boxes with TCAM forwarding it is much easier to get to the limit... on a Cat 3560 / 3750 once the table is full any additional routes overflow into software forwarding.
And if you have DFCs the table gets replicated there - so another place for hardware overflows to happen?
AFAIR when the box comes up it detects "lowest common denominator" for the various blades and pretends to be that. However who knows what happens when an engineer fits a non -3XL replacement card PFC / DFC and dynamically downgrades the chassis?
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