2
I can successfully ping, say, google.com via cmd using:
ping {IP ADDRESS} -T -L 1000
But if I use a packet size greater than "1001" I get a request timed out error. I know that the max amount of bytes I can send out is 65500.
Why is this?
P.S. My Internet is fine and I can access all websites through browsers.
Jhon Joe
Posted 2015-07-02T22:05:52.137
Reputation: 21
1
As grawity said in the comments when your packet is larger than the MTU size fragmentation will occur. Because ICMP packets contain very short messages, there is no legitimate reason for ICMP packets to be fragmented. If an ICMP packet is so large that it must be fragmented, something is amiss. For this reason some network administrators will block any ICMP packet that has the More Fragments flag set or that has an offset value indicated in the offset field.
rastaBob
Posted 2015-07-02T22:05:52.137
Reputation: 350
0
This looks like an MTU problem. If any router along your path to the destination does not support Jumbo Frames, then your ability to send much more than 1k (total frame size 1500) will stop at exactly that point, and you will end up with dropped frames beyond that hop. Even Jumbo Frames are limited to 9000 bytes, so if you want to send 65500 byte frames, then every router along that path will need to enable Super Jumbo Frames. The referenced Wikipedia article should clarify this issue.
vallismortis
Posted 2015-07-02T22:05:52.137
Reputation: 382
1Jumbo Frames aren't very important here, as IP already supports fragmentation; a 2000-byte ICMP message over 1500 byte MTU would just be sent as two IP packets. – user1686 – 2015-07-02T22:49:55.553
On windows the format for
pingis ip address after the options. So you should be usingping -t -l 1000 <ipaddress>– DavidPostill – 2015-07-02T22:57:42.450ping -t -l 9999 www.google.comworks here (Windows 7). Perhaps you can give an example that fails? – DavidPostill – 2015-07-02T22:58:57.963