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L2 and L3 statistics

The 2621 can process 20 kpps. Does this mean per interface? A combintation of input and output packets/sec?

When I do a "show int fa0/0" on my 2621, I see for 5 minute output rate and 5 minute input rate, each at about 150 packet/sec. Does this mean that I am only using 300 pps and I have plenty of growth capability to get to 20 kpps?

The 4507R can switch L2 and L3 at 48 mpps with a 64 Gbps switching backbone.

What commands can I use to see the current L2 and L3 stats?

Thanks,

RJ

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Accepted Solutions
Bronze

Re: L2 and L3 statistics

There's really no concept of input and output when it comes to PPS ratings. PPS refers to routed packets-per-second. A packet going through the router comes in an interface and goes out an interface, but is routed just once. So it will increment the counters of both interfaces (or maybe it comes in and goes out the same interface, but in this case it would increment both the 'input' and 'output' counters of that interface), but it's only one packet as far as the routed packets-per-second metric is concerned.

3 REPLIES
Bronze

Re: L2 and L3 statistics

PPS ratings are total, not per-interface. The ratings are based on 64 byte packets, however, in highly optimal test scenarios (i.e., no performance-reducing features such as ACLs or NAT enabled). PPS tends to drop as packet size increases, and since the average packet size on any real-world network is higher than 64 bytes, these PPS ratings aren't all that useful.

I tested a 2621 with TTCP a while back and it maxed out at around 40Mbps with 1500 byte packets. This is around 3400 PPS. So you're probably in good shape at 150pps, but don't plan on reaching 20k in a real-world network. The best way to tell the load of a software-based router like the 2621 is by looking at CPU usage (show proc cpu).

As for traffic stats, 'show int' is probably your best bet in addition to polling via SNMP.

Community Member

Re: L2 and L3 statistics

Thank you for the post. I appreciate your insight. When you say, "PPS ratings are total", do you mean both input and output ratings added together on all interfaces, or just one way on all interfaces?

Thanks,

RJ

Bronze

Re: L2 and L3 statistics

There's really no concept of input and output when it comes to PPS ratings. PPS refers to routed packets-per-second. A packet going through the router comes in an interface and goes out an interface, but is routed just once. So it will increment the counters of both interfaces (or maybe it comes in and goes out the same interface, but in this case it would increment both the 'input' and 'output' counters of that interface), but it's only one packet as far as the routed packets-per-second metric is concerned.

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