Re: Changing the Maximum Segment Size (MSS) of Kame MIP6 Free BSD4.4
Audsin wrote: I wish to change the Maximum segment size of the TCP. Can you please help me , where i should change the MSS of the TCP. Can you tell me where the default size of the MSS mentioned? $ sysctl -a | grep mss net.inet.tcp.mssdflt: 512 net.inet.tcp.v6mssdflt: 1024 Ex: $ sysctl -w net.inet.tcp.v6mssdflt=new_value To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message
Re: Changing the Maximum Segment Size (MSS) of Kame MIP6 Free BSD4.4
Nicolas Mallet wrote: Audsin wrote: I wish to change the Maximum segment size of the TCP. Can you please help me , where i should change the MSS of the TCP. Can you tell me where the default size of the MSS mentioned? $ sysctl -a | grep mss net.inet.tcp.mssdflt: 512 net.inet.tcp.v6mssdflt: 1024 Ex: $ sysctl -w net.inet.tcp.v6mssdflt=new_value These don't work the way you'd think they work from their names. They are just initial (default) values, not bounds or limits. -- Terry To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message
Re: Changing the Maximum Segment Size (MSS) of Kame MIP6 Free BSD4.4
Terry Lambert [EMAIL PROTECTED] wrote: Audsin wrote: I am Dev, doing my research in Centre for Telecommunications Research, King's college London. My research project involves evaluating the performance of MIP6 TCP in the presence of fragmentation and without fragmentation. I am using Kame MIP6 for Free BSD 4.4 and have configured gif0 interface for ipv6ip tunnel. I wish to change the Maximum segment size of the TCP. Can you please help me , where i should change the MSS of the TCP. Can you tell me where the default size of the MSS mentioned? man ifconfigcr /mtucr The original question asked about the TCP MSS, not the MTU. Looking at ifconfig isn't going to help. I don't have the 4.4 source sitting around, but assuming that it hasn't changed much, in 4.6.2 you can find (or change) the defaults in /usr/src/sys/netinet/tcp.h. The default for TCP4 is 512, and 1024 for TCP6. You can get at them via sysctl (along with a lot of other TCP-related things): net.inet.tcp.mssdflt: 512 net.inet.tcp.v6mssdflt: 1024 Note that the actual MSS is negotiated; if both ends can't support the same value, the smaller is chosen. For MTUs, in case that's really what you meant, it's even more strict and depending on how the transport layer is implemented, it may be impossible (or reckless) to increase the MTU. For example, on ethernet many switches simply do not support an MTU larger than 1500. -Dan To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message
Re: Changing the Maximum Segment Size (MSS) of Kame MIP6 Free BSD4.4
Daniel Ellard wrote: man ifconfigcr /mtucr The original question asked about the TCP MSS, not the MTU. Looking at ifconfig isn't going to help. Actually, the original question is about how to cause the creation of fragments, for the purposes of testing. The MSS question is kind of based on a loose assumption about where baby frags come from, which isn't quite correct. Note that the actual MSS is negotiated; if both ends can't support the same value, the smaller is chosen. This is the problem. The MSS can be negotiated up to the MTU size from the default, or down, to match an intermediate hop. The only thing changing the default will do for you is increase the negotiation time. For MTUs, in case that's really what you meant, it's even more strict and depending on how the transport layer is implemented, it may be impossible (or reckless) to increase the MTU. For example, on ethernet many switches simply do not support an MTU larger than 1500. This is the one thing he *can* hard-code, via ifconfig. MSS is not hard-codeable. There's an outside chance that he wanted the MTU larger (e.g. 9k for jumbograms on gigabit hardware). Actually, hardware MSS negotiation doesn't work between some gigabit cards, and has to be set manually on both ends to get the higher number. But since he was talking about fargs vs. no frags, it's a good bet that what he wanted was: MTU X MTU X/3 host1 router host 2 So that frags are created when transmitting data from host1 to host2. -- Terry To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message
Re: Changing the Maximum Segment Size (MSS) of Kame MIP6 Free BSD4.4
I think that you just burned all possible bridges with your rampant cross posting. At least I hope so. -- If it's moving, encrypt it. If it's not moving, encrypt it till it moves, then encrypt it some more. To Unsubscribe: send mail to [EMAIL PROTECTED] with unsubscribe freebsd-hackers in the body of the message
