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UC540 Throughput speeds

Pete Matheson

Recently installed a UC540 and I've noticed that the UC540 is severely capping our broadband speeds.

We have a 100MB connection here presented by a virgin modem.

When connected via the UC540, the best speeds we see (with inspection & ACL's disabled) is 30MB.

Has anyone else experienced this?

Official UC support told me it's a hardware limitation on the UC540. 

6 Replies 6

Darren DeCroock

Hello Pete,

This is the only info I have on this subject at this time:

Thank you,


Keep in mind that from a hardware platform standpoint, a UCS5xx is just a pimped a out ISR 28xx.

50-80mbps throughput is what you should expect.

If you're connecting to a FTTx/GPON/MetroE, upgrade to a Cisco 2951 on the WAN edge and have the UCS5xx route via bridging into your switching core via a trunk link on the WAN.

Do your NAT/PAT/IPSEC/Inspection on the 29xx ~BAS

UC540 will only do 30Mbs roughly.  We had to add a switch and second router for the LAN to achieve full throughput.

At this point, the IRB/Routing/Switching/WIFI inside the UCS5xxx is totally obsolete; the only practical solution is to make the UCS5xx a client to a Layer3 Switch/Router.

I recommend a 802.1q Trunk; match your VLANs with VTP, and only put an IP address on 1x BVI associated with one Bridge/BVI by putting that VLAN into the Bridge.

I recommend Cisco 2960XR or Cisco 3860:

David Trad
Rising star
Rising star

Hi Pete,

The UC-540/560 WAN ports do not seem to have the same throughput speeds as does the original UC-520... I don't know why this is as I have never bothered to see if the hardware is actually different.

However what I can tell you is that you should be able to get about 75-80Mbps on the WAN port, then you have to factor in other stuff that the IOS does with the routing as the UC's are not hardware based routing, and you take off a further 20-30Mbps throughput.

So I would pin the maximum throughput on the UC's at about 60Mbps if you were lucky, I have personally put this to test on well over a 100 deployments, pretty much gave up measuring this after the speeds were consistent.

My advice if you want to achieve full 100Mbps is to get a proper WAN router (Ethernet based) like the new SRP-500 series which can achieve almost the full 100Mbps (Not quite average speed throughput was about 96Mbps). Then you plug it into the trunk port of a decent Cisco switch and set the smartport role as a router using CCA.

Now I must warn you of something, and I have never spoken out about this before, but recently I have been forced to look into older jobs I have done last year before I took a Hiatus from working on Cisco appliances, and discovered that the new Sx300 series switches are just not cut out and fall short desperately of the quality that the ESW switches had, the amount of complaints I have received in the last 5 months regarding these switches is mind blowing, I do not know why as this is not something I have seen before with Cisco in probably over 6-7 years, and I am not sure what other alternative Cisco SMB switch can be used - Maybe they will address some of the issues seen in future firmware updates, I truly hope so.

Good Luck



Cheers, David Trad. **When you rate a persons post, you are indicating a thank you or that it helped, but at the same time you are also helping to maintain the community spirit - You don't have to rate posts and you wont be looked down upon :) *

We also have a UC540 and our internet speed is 50Mbps/10Mbps but the UC540 is capping the speed to 30Mbps.  I have a ticket open with Cisco (horrible support on legacy devices by the way) now for almost 30 days.  They do not have fast enough internet to test in their lab.  We did disable some lists and no change.  Shouldn't the 10/100 WAN port give me 50Mbps???  When I go direct from modem to PC I get 53Mbps.  This is very frustrating.

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