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Default config of SG300 20 port gigabit managed switch -

Hi All - I have a new SG300 20 port gigabit managed switch. My environment consists of a few Windows servers. One of the Windows servers backs up it's image nightly - Roughly 15 GB. During this backup, ALL other machines lose network connectivity completely while the backup occues and I cannot determine why. I also lose remote connectivity to the server backing up. I'm fairly new to managed switches, but it is the default config.

Any ideas on where I can begin looking?

Soulja

Here is the guide for your switch:
http://www.cisco.com/en/US/docs/switches/lan/csbms/sf30x_sg30x/administration_guide/78-19308-01.pdf

What you want to do is create a separate vlan for the the backup server and whatever it's backing up to. Than you can set up vlan rate limiting which will limit the traffic coming from the vlan that the server is in. Currently it sounds like the server is slamming the switch.

Additionally, is the backup occurring during business or off hours?

Soulja

Page 184 Vlan Management

Page 342 Vlan Rate Limiting.

polaris101

ASKER

Hi Soulja - The backup is occurring off hours - The problem with creating VLANs, is that I need these machines to be on the same subnet.

I thought a switch provided dedicated bandwith to the switch port, and not 'shared bandwidth' like a hub provides. Or do you think it could be the CPU on the switch this is being crushed?

Soulja

A switch provide separate collision domains, but with your default setup, everything is in the same broadcast domain. Using vlans will allow smaller broadcast domains and better traffic flow. I would try separate vlans, before ruling that the switch's can't handle the traffic.

polaris101

ASKER

What you are saying makes sense, however, we are talking about a VERY small environment with only a few servers. If I had a more complex envrionment, breaking the switch into VLANs would makes sense...but I'm not quite sure it would make much of a difference here.

Soulja

Well another option is the limit the bandwidth on the port that the server is connected to.

Check out page 340.

If the issue still exist then I would have to say that the switch's cpu can't handle the traffic.

polaris101

ASKER

Would enabling Jumbo frames make a difference? Did you mean page 330? It looks like 330 shows you how to config bandwidth limits.

Soulja

340 of the Adobe document, but yes, 330 of the actual page numbering.

If your server supports jumbo frames, you can try it, but I am skeptical that would resolve the issue, if it concerns the cpu.

polaris101

ASKER

I'm only going to modify the "ingress rate limit", correct? I'll leave "egress shaping rates" disabled, correct?

Soulja

Yes, if the traffic is mainly transmit traffic from the server than ingress is the limit you want to set.

polaris101

ASKER

Also, it is currently in "Basic" QoS mode... perhaps disabling QoS all together would make a difference?

polaris101

ASKER

Just so I'm clear.

Server A on Switch Port A backs up to Server B on Switch Port B - What switch port am I modifying? Ingress on Switch port B, correct?

Soulja

Server A's switch port. Don't disable QOS.

polaris101

ASKER

Ingress is inbound though, correct?

Soulja

Yes, inbound on the port, not inbound on the server.

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polaris101

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Soulja

Don't know at all, why that would happen. Even so, I would wait to see if the issue reoccurs. A switch shouldn't need to be rebooted. You can make sure you have to most updated firmware/ios on the switch. Could be a buggy version.

polaris101

ASKER

Issue has not occured again after reboot