Router and WAN throughput

[ADWAITANANDADAS]

Is there any datasheet where we can find the maximum WAN throughput (provided by ISP) a router can support?

[Georg Pauwen]

Hello,

for which model (e.g. ISR 4431) ?

[Joseph W. Doherty]

By an ISP, doubtful.

However, by the router maker, possibly.  Routers, if software based, often have variable performance which depends on traffic mix and router configuration.  Such may not be well documented.  Sometimes, additional performance information might be provided by a 3rd party test lab, some of that possibly paid for by router maker.

Also, performance breakdown often not per WAN vs. LAN, but they usually don't vary much (because router performance often cited as packets per second for a certain size).

[ADWAITANANDADAS]

Thanks, Georg and Joseph.

We were using 10 to 20 Mb Broadband links (DSL/Dialer) link at most of the locations. They were noticed to be used efficiently. But even after upgrading those to 50 Mbps or more, the performance doesn't improve much. The router we use mostly of Cisco 4331, 2911, 2901.

[Joseph W. Doherty · Accepted solution]

BTW, one quick check, to determine if your putting too much demand on a small Cisco ISR is to check its CPU history.

If your DSLs links are aDSL, i.e. lower upstream vs. downstream bandwidth, and/or port speeds are more than available bandwidth, one common issue is sending the data too fast to your provider, where, when "overrate" they might drop the excess.  So, for these cases, it's often of benefit to shape your traffic for actual available bandwidth.

For routers like the small 29xx ISR, 50 Mbps could exceed their capacity.  I've attached a Cisco document that shows the performance of your 2911 and 2901 under several conditions (where, you should notice, performance can vary a good deal).

For your 4331 ISR, with the 4K ISR series, Cisco implemented performance license caps, so those routers, generally, can always guarantee that level of performance with their "base" license.  If you've upgraded them to their "performance" license, those router can still, often, meet that license cap too.  If you've upgrade them to their "boost" license, they operate much like the earlier ISR, i.e. whatever the hardware can deliver.  You might find this Miercom report interesting: https://miercom.com/pdf/reports/20150817.pdf.

[e.ciollaro]

Hi

routers performance depends on what they are required to do,  more service configured (I mean NAT, ACL, QoS, ...) means less throughput but ISR 4000 architecture considerably reduced this drawback in respect to ISR G2 (1900, 2900 and 3900) so I'm not sure that these problems depends on router. Which is the real guaranteed bandwidth of that links ? In my country DSL (ADSL, VDSL) links have a very low guaranteed bandwidth  in respect to peak. Did you ask your ISP about this ?

Bye

Enrico

[ADWAITANANDADAS]

We have checked the speed is much promising when we test it on the laptop directly. But the speed suppressed a lot when connected to a router. Do we know if a router can process the packets to a specified bandwidth when WAN comes into the picture?

[e.ciollaro]

WAN is not a problem for routers, their are made to connect to WAN. As I told the only problem is what they are required to do but because you wrote that you have tested the bandwidth directly from PC, I wonder how did you measure bandwidth usage after the router has been connected to the WAN. One common problem in measuring download and/or download speed, is using an online tools  (like Ookla Speedtest) from a PC; this is not the right way to do because the results depends on many factor including how many host are connected to the router in the moment  and if they are sending/receiving data (other factors are LAN usage, the PC itself, how the ISP reach the online test . etc,). Could you explain how did you test ?

Bye,

Enrico