We help IT Professionals succeed at work.

D-Link DIR-615 turned in to a bottleneck?

houlahan
houlahan asked
on
I have recently joined virgin media (cable 10mb) they sent me a cisco modem and a D-Link DIR-615 wireless router for the last few days has been running at 2mb but if i just plug the modem straight in to my Ethernet port i get the full 10mbs can i be certain that this is my router that is causing the problem?
thanks in advanced.
Comment
Watch Question

Top Expert 2010

Commented:
Did it ever run at 10mbps?  You might check out my article here about setting the proper MTU of your WAN interface on the D-Link.  See if that helps.

http://www.experts-exchange.com/viewArticle.jsp?aid=3110

Author

Commented:
yea about 3 days ago it was working normally i was getting download speeds up to 1.1mbps now i barely get 100kb my MTU is currently at 1500 which is what it was set at origanaly
Top Expert 2010

Commented:
You haven't enabled any QoS or bandwidth management on the D-Link have you?  That or the MTU is the only thing I can think of.  It's possible that the ISP changed something on their router causing your WAN interface to fragment packets.  Finding out where your MTU needs to be would might help us figure that out.  It's fairly easy to figure out too.

Author

Commented:
ok i looked at the link you gave me and i got

C:\Documents and Settings\Houlahan>ping www.google.com -f -l 1436

Pinging www-tmmdi.l.google.com [66.102.9.104] with 1436 bytes of data:

Reply from 66.102.9.104: bytes=64 (sent 1436) time=48ms TTL=52
Reply from 66.102.9.104: bytes=64 (sent 1436) time=40ms TTL=52
Reply from 66.102.9.104: bytes=64 (sent 1436) time=136ms TTL=52
Reply from 66.102.9.104: bytes=64 (sent 1436) time=32ms TTL=52

Ping statistics for 66.102.9.104:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 32ms, Maximum = 136ms, Average = 64ms

anything over that gave me Packet needs to be fragmented but DF set.
so should i set me MTU at 1436?
Top Expert 2010

Commented:
You'll then want to add 28 bytes to 1436 giving and MTU of 1464.  20 bytes are reserved for the IP header and 8 bytes must be allocated for the ICMP Echo Request header.

So, give 1464 a try.

Author

Commented:
nope nothing :/ still getting the same 2mbps speeds instead of the 10mbps i was getting a couple of days ago and what i get when i just plug the modem in to my pcs Ethernet
Top Expert 2010

Commented:
forgot one more thing....is the wan set to autonegotiate speed and duplex? might try static 100/full or 100/half...something along those lines.  sorry the mtu wasn't a hit.

Author

Commented:
can't find anywhere where you can set speed and duplex only thing i can see which resembles that is in VCT INFO says:

Internet              100Mbps FULL Duplex      
LAN1              100Mbps FULL Duplex      
LAN2              Disconnected      
LAN3              100Mbps FULL Duplex      
LAN4              Disconnected

but can't change it :/
Top Expert 2010

Commented:
I found an emulator for your model on the internet and can see that they can't be changed...bummer.  So, you're not performing any QoS or bandwidth management?  I'm out of ideas otherwise.

Author

Commented:
nope nothing like that :/ got in touch with virgin media and they just said that's normal because the router shares the connection between the 4 computers which i have which can't be correct if i was able to download at 1.1mbps even when all the computers were on in the house.
Top Expert 2010

Commented:
yeah...i'm not so sure that's correct unlesss you've got someone on your network streaming movies or downloading software, etc.  i don't know if this model does syslog stuff...you could watch the traffic and see what comes across.
Commented:
Rung virgin media and they were capping me
Top Expert 2010

Commented:
bummer, gald you figured it out, but very bitter sweet.