OK, This tells me it's 1460 bytes I assume... ( it's an old DLink router ).
From 10.100.0.1 icmp_seq=1 Frag needed and DF set (mtu = 1460)
...
Whereas locally it's 1500 bytes.
If I log on to the router,
# ifconfig br0
br0 Link encap:Ethernet HWaddr 00:1B:11:D3:31:A9
inet addr:10.100.0.138 Bcast:10.255.255.255 Mask:255.0.0.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 ASYMMTU:1500
RX packets:120497052 errors:0 dropped:0 overruns:0 frame:0
TX packets:139131496 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:2397316505 (2286.2 Mb) TX bytes:1297785614 (1237.6 Mb)
# ifconfig ppp0
ppp0 Link encap:Point-Point Protocol
inet addr:a.b.c.d P-t-P:a.b.c.254 Mask:255.255.255.255
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1460 Metric:1
ASYMMTU:1500
RX packets:72694426 errors:0 dropped:0 overruns:0 frame:0
TX packets:46502303 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:836829099 (798.0 Mb) TX bytes:1469766225 (1401.6 Mb)
So it looks like the ADSL connection has a MTU of 1460b, and nothing
seems to be reporting any errors.
Where to from here? I'm also confused as to why it's changed...
Steve
On 06/06/15 21:10, Fraser McGlinn wrote:
Hi Steve,
Have you checked the MTU and tcp-mss? This smells MTU related.
Generally speaking most DSL’s should be either 1492 or 1500 bytes. So to check
this do the following:
ping -M do 8.8.8.8 -s 1464 #check if its 1492 bytes
ping -M do 8.8.8.8 -s 1472 #check if its 1500 bytes
Remember the size value is the payload size so this excludes the IP header (20
bytes) and ICMP header (8 bytes).
Cheers,
Fraser
On 6/06/2015, at 3:00 pm, steve <[email protected]> wrote:
Hi folks,
Am nearing wits end... been away on hols for a month and my network performance
has plummeted.
The best way of describing the problem is that you need to refresh a web page
before you get any content. In addition, bulk loading across a VPN ( eg scp )
fails regularly.
Basic design of network: 'firewall' server runs fail2ban and links upstream
ADSL to local wireless and wired subnets. It also provides DNS ( caching server
), DHCP, OpenVPN etc services.
I initially thought it was a DNS problem, and have migrated from the local (
Voda ) DNS servers to OpenDNS, having briefly tried Googles resolvers on the
way. No improvement.
Any thoughts on what I can try to identify the real problem? My thought is that
the GCSB are involved somewhere along the line, but as a SysAdm I am paid to be
paranoid!
Cheers,
Steve
--
Steve Holdoway BSc(Hons) MIITP
http://www.greengecko.co.nz
Linkedin: http://www.linkedin.com/in/steveholdoway
Skype: sholdowa
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_______________________________________________
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--
Steve Holdoway BSc(Hons) MIITP
http://www.greengecko.co.nz
Linkedin: http://www.linkedin.com/in/steveholdoway
Skype: sholdowa
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