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QNX Operating System/Discussion/OSTech/MTU configuration on IPStack/List of Posts
Forum Topic - MTU configuration on IPStack: (2 Items)
   
Update
Christian Scheuch(deleted)
02/14/2012 4:13 AM
post91545
MTU configuration on IPStack   
Hi,

We have configured 
 MTU 1504 on en0 and 
 MTU 1500 on en1 
But we have observed that during Ftp negotiations 1464 is advertised.
Incase MTU 1500 is configured both on en0 and en1, 1460 is advertised.


[Packet summary from wireshark]
13	14:35:28.886466	172.18.4.118	172.18.4.244	TCP	cisco-ipsla > ftp [SYN] Seq=0 Win=65535 Len=0 MSS=1460
14	14:35:28.887697	172.18.4.244	172.18.4.118	TCP	ftp > cisco-ipsla [SYN, ACK] Seq=0 Ack=1 Win=16384 Len=0 MSS=1464
where 172.18.4.244 is the IP for the site running on QNX

Pls. let us know what is the probable cause.

regards,
Christian Scheuch(deleted)
02/14/2012 4:17 AM
post91546
Re: MTU configuration on IPStack   
Here are the details of ifconfig

ifconfig
lo0: flags=8009<UP,LOOPBACK,MULTICAST> mtu 33212
        capabilities=7<IP4CSUM,TCP4CSUM,UDP4CSUM>
        enabled=0<>
        inet 127.0.0.1 netmask 0xff000000
en0: flags=843<UP,BROADCAST,RUNNING,SIMPLEX> mtu 1500
        address: 00:40:43:15:1a:30
        inet 192.168.255.126 netmask 0xffff0000 broadcast 192.168.255.255
en1: flags=843<UP,BROADCAST,RUNNING,SIMPLEX> mtu 1504
        address: 10:71:61:03:38:00
        inet 172.18.4.244 netmask 0xffffff00 broadcast 172.18.4.255
en2: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        address: 1e:42:86:27:01:08
        inet 192.168.255.126 netmask 0xffff0000 broadcast 192.168.255.255
        inet alias 192.168.255.125 netmask 0xffffff80 broadcast 192.168.255.127
vlan4095: flags=843<UP,BROADCAST,RUNNING,SIMPLEX> mtu 1500
        vlan: 4095 parent: en0
        address: 00:40:43:15:1a:30
vlan799: flags=843<UP,BROADCAST,RUNNING,SIMPLEX> mtu 1500
        vlan: 799 parent: en0
        address: 00:40:43:15:1a:30
        inet 10.10.10.12 netmask 0xffffff00 broadcast 10.10.10.255

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