[GTALUG] Rogers and MTU size

James Knott james.knott at rogers.com
Sun Jan 4 19:20:55 UTC 2015


On 01/04/2015 01:51 PM, Scott Allen wrote:
> On 4 January 2015 at 12:55, James Knott <james.knott at rogers.com> wrote:
>> You can
>> verify the MTU with a ping -s 1500 <destination>.  If that works, then
>> you have a 1500 byte MTU along the entire path to the destination.
> My router says that the address of the gateway that it's connected to
> is 24.246.95.97. If I ping this address I get:
>
> $ ping -s 1500 24.246.95.97
> PING 24.246.95.97 (24.246.95.97) 1500(1528) bytes of data.
> 1508 bytes from 24.246.95.97: icmp_seq=1 ttl=254 time=12.2 ms
> 1508 bytes from 24.246.95.97: icmp_seq=2 ttl=254 time=13.5 ms
> 1508 bytes from 24.246.95.97: icmp_seq=3 ttl=254 time=15.7 ms
> 1508 bytes from 24.246.95.97: icmp_seq=4 ttl=254 time=12.1 ms
> ^C
> --- 24.246.95.97 ping statistics ---
> 4 packets transmitted, 4 received, 0% packet loss, time 3004ms
> rtt min/avg/max/mdev = 12.151/13.429/15.765/1.449 ms
>
>

That shows you have a 1500 byte MTU, so Teksavvy is doing things
properly.  Either they're saying to use 1500 or not using option 26 at
all.  Fire up Wireshark to see.



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