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39

Just use a command like: ethtool eth0 to get the needed info. Speed: 1000Mb/s


38

80 MB / second is actually pretty good! That's about 640mbps, which is pretty darn close to the gigabit capacity of the NIC. If you take into consideration the TCPIP overhead, and disk speed you're probably at your maximum speed.


21

Try putting this to your /etc/sysctl.conf # General 10gigabit/LFP tuning net.core.rmem_max=16777216 net.core.wmem_max=16777216 net.ipv4.tcp_rmem=4096 87380 16777216 net.ipv4.tcp_wmem=4096 65536 16777216 net.ipv4.tcp_syncookies=1 net.ipv4.tcp_max_orphans=1048576 net.ipv4.tcp_orphan_retries=2 # Removes some internal buffering net.ipv4.tcp_low_latency=1 # ...


18

Gigabit Ethernet over fiber and 100Base-LX10 aren't compatible. Further, the gigabit switch will not "fall back" or negotiate speed over fiber. This behavior is perfectly normal for fiber-based Ethernet. While copper-based Ethernet typically does have speed and duplex negotiation capabilities, fiber-based Ethernet does not. It sounds like you need to get a ...


18

While Ethernet runs should extend up to 330 feet, as you've found many pieces of cheap equipment don't meet that specification. The most reliable solution you'll find here is to run fiber from one building to the next. It provides inherent galvanic isolation, so there's no need for surge suppressors (which probable don't work the way you think they do in the ...


17

Use mii-tool to watch the negotiated network speed. Ex. eth0: no link eth1: negotiated 100baseTx-FD, link ok


16

Since mii-tool is deprecated, I'd go for ethtool. Can't you check the other sides opinion of the link speed, btw? mii-tool and ethtool are known to disagree in certain circumstances; you can find bugreports of that on a host of websites. What driver are you using? At least tg3 is known to be a subject of disagreement between the two tools. UPDATE: Checked ...


13

Buy a managed switch, disable learning and you have a hub. But, seriously, try to find the reason for this policy. It sounds like somebody read the Ethernet limitations on segment size and didn't understand what it meant.


13

As Khaled mentioned, you should be able to run ethtool with just the interface as an argument. This will list the supported speeds, the advertised speeds, the current speed, and a bunch of other things too: Settings for eth0: Supported ports: [ TP ] Supported link modes: 10baseT/Half 10baseT/Full 100baseT/Half ...


12

I can't imagine a reason why you would be rebooting switches often enough in any environment to even worry about this. Any reboot of a switch should be done in a maintenance window and then a few minutes isn't going to be a big deal. I'm not sure how you think that booting time reflects the switch performance. Switches, like most embedded devices, will ...


11

This question is still missing an authoritative reference, so here it goes: There is no minimum length specification to a 1000BASE-T segment. Charles E. Spurgeon - Ethernet, the Definitive Guide, p. 163.


11

You can use Cat5 for really short runs in a Gigabit environment, but it isn't recommended. Cat5e is fine in almost all scenarios, but if you're wiring from scratch, use Cat6, it's only fractionally more expensive. Good Wikipedia info here - particularly the link about "far-end crosstalk".


11

Wait - you're asking for server grade NICs but want to buy a 350 bucks switch?! I don't get that ... Usually "server grade" 48 port GigE switches go for somewhere around 3000-5000 USD list price. Maybe you want to look out for switch side things like stacking for cross-stack LACP. Regarding the NIC, things like: proper DMA interface and good drivers that ...


11

Welcome to the strange and mysterious world of jumbo frames! It's normal that jumbo frame ethernet gear has MTU > 1518 and < 65K byte and you have to find a setting that is the lowest common denominator across your L2 domain to enable proper jumbo traffic. My guess is that your ping/ICMP implementation only works for 8192 bytes payload, so 8164 + 28 ...


10

No easy way to find out or to help you without more information. Fibre connections are good for linking routers to other routers or very high end equipment to routers. If the server and the router support fibre, why not! However, as for sustained bandwidth and if 1GB/hour is possible... Follow this advice: Cheap £20 switch = bad Expensive gear = good ...


9

Sounds like there's something wrong with the switch port, or with the physical media. If your autonegotiate puts you at 100Mb and you can't force it to 1Gb, then you've likely got a physical problem. That said, if you're going to force 1Gb/s, you should make sure you do it on both sides. Don't take the NIC off of auto without also taking the corresponding ...


8

Check Max Ethernet and TCP Throughput Okay, check Protocol Overhead. This one has information about theoretical speed. Theoretical maximum UDP throughput on GigE using jumbo frames: (9000-20-8)/(9000+14+4+7+1+12)*1000000000/1000000 = 992.697 Mbps Theoretical maximum TCP throughput on GigE without using jumbo frames: ...


8

In general, GigE should be faster than Firewire 800. There are some variables at work that may make FireWire faster, but except for Ethernet congestion from other traffic they're edge cases. If you're looking to connect more than 2 hosts, Ethernet is by far the better choice.


8

PowerConnect switches are OEM'd by Delta Networks, from Taiwan. I'm using 6248's and 6224's with two Customers (one using powered and one usign non-powered versions). They're much cheaper than a feature-similiar Cisco switch, and they've worked well. The first Customer got theirs in late 2007, and the second in fall of 2008. We're only using layer-3 ...


8

Why stop at gigabit? This device allows you to connect a pci express 16x card using an external box and the laptop's expresscard/34 slot. Now you put a 10gig card with sfp+, like one of these, into that. While you're at it, grab a couple of passive fiber taps. Now you've got a box that allows you to snoop any link you may encounter short of a sonet link, ...


8

Your 32-bit, 33Mhz PCI bus can transit a maximum of 1,067 megabits per second (Mbps) or 133.33 megabytes per second (MBps). Gigabit Ethernet can transit 116 megabytes per second (MBps). So although you card should be able to fully saturate the line you'll actually only ever get about 90% utilisation because of various overheads. Either way if you're ...


8

Full-duplex means that your transmit and receive are independent: you can transmit at 1Gbps and receive at 1Gbps at the same time. The question of whether you'll achieve full line rate or not is another matter - there's plenty of factors which will prevent you getting full line rate. That's beyond the scope of this question though. Also, minor point, but ...


8

I've setup a lab with 2 servers each one with 2 Gbit NICs connected back-to-back by 2 CAT5e cables. Using Debian 5.0.5 freshly installed on both servers I configured a bonding-master interface bond0 with eth0 and eth1 on both machines using bond-mode 0 (balance-rr) since there's no need to have anything more complex than this really. The configs ...


7

No, only the 100/mb clients to the switch will be affected. However, you need Cat5e minimum to run gigabit (Cat6 is certified to run gigabit speeds). So if all your cabling is Cat5, then a gigabit switch won't do you any good.


7

I've had good luck with iSCSI and moderate workloads, but of course whether or not the single gigabit connection will be able to keep up with your environment is not something we'll be able to help you determine. The one glaring omission I noticed immediately with your plan is that, by only using a single port for your storage, you have no option for ...


7

I'd say you'd be lucky to break 100MB/s. In theory, yes, you could transfer 1000Mbps, or 125MB/s, but between the various layers of overhead (Ethernet and IP headers, iSCSI itself, the fact that some time has to be spent between packets) you will never actually see that. Also, don't forget that 125MB/s (or less) is what you'll see flying out of the NAS ...


7

If you see error counters continuously increase on specific ports, it very likely is either a duplex mismatch or bad cabling. In rare cases you might be seeing a defective PHY on either side (switch or NIC), driver problems on the station side or a buggy switch. So first, check the duplex settings on the switch and the connected station for the port(s) in ...


6

If your switch isn't non-blocking then often the uplink ports are non-blocking, so they could have that benefit, otherwise I can't think of any other real differences between types of port.


6

When sizing a switch one thing to keep in mind as to what the "fabric" of the switch can support. Just because a 48 port switch has for example 48 Gigabit ports doesn't mean that the switch can handle all 48 ports pushing 1GB in each direction (Full Duplex) at the same time. I'm afraid however that even though some switches say they might have a 48GB fabric ...


6

That depends on whether you're running in half duplex (1 gigabit total) or full duplex (1 gigabit each direction). Of course, you'll never hit these theoretical performance limits.



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