How to display maximum throughput of the routing engine on a XOS switch

[George_van_Asse]

We would like to know how much data is going through the routing engine of a BD8800, in other words how much traffic is routed by the switch (the actual maximum we would like to learn)

[Stephane_Grosj1]

Hi George,

Routing is performed in HW and you can achieved the same throughput in L3 than in L2. Because everything happens in HW, to keep that L3 throughput, you need to stay within the HW capacity of the L3 tables, otherwise slow path (CPU) may happen.

Following the link Drew gave you, you can find all the relevant information.

Looking at the first table of the DS on page 5: You have a BD8810 with c-series modules and a single MSM-48c. You have then a backplane bandwidth capacity of 24Gbps per Slot. You can double that adding a second MSM-48c.

Does it mean the max throughput is 24 * nb_slots? Yes and no. It depends on the traffic pattern and how many L3 entries are considered.

- What about the traffic pattern? I/O module can perform local forwarding, so if your destination is on the same chip, the backplane is not used. Worst case would be every single packet has to go through the backplane.

- What about L3 tables? Simplifying a bit, I/O modules store all the forwarding information in their chip. As long as you stay within their HW capacity, traffic is HW forwarded. But if you put too many entries (too many LPM routes, too many ARP entries, Multicast...) then the chip will not be able to HW forward everything, and the CPU will be used.

You can issue that CLI command to have a view of your L3 resources usage. It's better to execute it during a normal day with a normal activity:

sh iproute reserved-entries statistics

Your limits is listed on the same table of the DS, and this output will also give you the limits. It could be useful to know what EXOS version you're using.

So, assuming you're within the HW capacity, your worst case throughput is 24*5 (slots used) = 120Gbps (or 240Gbps in Marketing math).

[George_van_Asse]

Hello,

Yes, we would like to see "how much traffic is currently routed".....

[Stephane_Grosj1]

Hi,

The theoretical values can be achieved. But maybe what you want to know is how much traffic is _currently_ routed on your switch?

The "sh ipr reserved stat" command will tell you how many LPM/Hosts/Multicast entries are currently programmed on every slots. This is not the routing table, but really the HW (not a software view, a hardware view).

[George_van_Asse]

Thanks for your reply. Again I am not looking for theoretical values of the capacity of this switch.
I am looking for the maximum amount of routed traffic on the switch during normal operation.
Correct me if I am wrong but the "show iproute reserved-entries statistics" is more a summary of the ammount of routes in the route table...