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New Member

SA520 throughput performance

I am bringing up a new network and am using SA520 to provide the firewall behind my Comcast connection. When connected directly to the cable modem, I get downloads of close to 50Mbps but the speed drops to around 5Mbps when going through the SA520. I have the latest firmware 2.1.71 and only 2 firewall NAT rules. On the Attack Checks, I have all the WAN and LAN security checkboxes checked. I have tested without any checkboxes checked and it has made no difference. What am I missing?

3 REPLIES
New Member

Re: SA520 throughput performance

I worked with a very patient and knowledgeable Cisco support engineer and resolved the issue. Made the following changes:

1. Modified settings in Networking -> Port Management so that Auto was enabled.

2. Used a sniffer such as WireShark to detect network packet size issues. Navigate to Networking -> IPv4 Config and modify MTU size to 1500. This value will vary based on ISP.

Also checked the Comcast modem to make sure that all ports were set to Auto enabled. We are able to get the full 50/10.

New Member

SA520 throughput performance

Do you have IPS turned on?  With IPS turned on (we have an SA540) we can only achieve ~22 Mbps download.  With it turned off, we can achieve our full 30 Mbps.

With IPS turned on, the CPU max's out very easily under small load.  With IPS turned off, even with constant 30 Mbps downloading and 5 Mbps uploading, along with other intranet traffic going on, the CPU cruises along at about 10%.  It could easily achieve the advertised 300 Mbps.

New Member

Re: SA520 throughput performance

Appreciate your suggestion but we don't have IPS turned on. However, with the changes that we made to the MTU packet size and setting port management to auto, we are now able to get our full capacity.

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