Packet loss with libpcap on a loopback interface
I'm trying to write a protocol decoder using libpcap. I'm having
problems with a simple test program that sends a simple "hello world"-
string on a TCP port. I intermittently receive some "TCP ACKed lost
segment" for the packets that are sent/received. My best guess is that
this is related to either libpcap or my setup since I get the same
behaviour using my own protocol decoder as with Wireshark. The fact
that the segments are not lost, other than for libpcap, are obvious
since the test application receives the data without any
retransmissions going ...Packet loss on larger packets only
Being stumped on a problem with a Win2K (SP4) box.
Recently started to have network performance problems, no recent
configuration changes that I can identify that might be responsible.
I've narrowed the problem down to an issue where small packets are OK,
but I get lots of packet loss on packets larger than 200-250 bytes,
particularly over 300 bytes. This was tested by using "ping -t -l
<size> <destination>" for hosts either on the same LAN or over an
internet link. Problem manifests itself whether pinging from or to
the affected host.
This box also h...packet loss because of big packets
The following problem occurs in my network:
The command 'ping anyhost' works well without packet loss. Ping sends
packets with a size of about 65 Bytes. If I grow the packet size with
the parameter -s, I have got packet loss. The command 'ping -s 65507
host' works well for some hosts, for others not (100 % loss).
Does this indicate bad network components? What does this mean for
other protocols like UDP or TCP?
Thank You for Your help!
This might be due to certain hosts not supporting ICMP Echo reply with
larger packet sizes.
htt...New packet loss issue
I've submitted this as a Sun case, but I thought I'd post here as well
to see if anyone else has experienced this problem. Any ideas?
The server is an x4100 M2 running Solaris 10 11/06 x86. Patches were
current as of 4/9/2007, including a reconfig reboot at that time.
Yesterday, the server was rebooted and afterwards the packet loss was
noticed immediately. Note that as part of troubleshooting this
problem, I've brought the patches up to date as of yesterday,
performed a reconfig reboot, as well as performing a cold boot (with
power cables completely removed).
...Reapeatable packet loss on ulip interface over Solaris TCP on 100Mbps
I use VxSim with ulip over Solaris8.
Whenever the gap between 2 packets < 10usec -
The second received packet does not arrive to ulip interface.
This cause a very slow TCP connection.
On 10BaseT it never happens (probably because the inter packet gap > 10 usec).
Did anyone encountered this problem?
Can anybody help me in the following subject?
Situation 1. Router 1 (2500 series) have 2 Serial Interface connected
to 2 Branches. Loopback Interface is also configured for the Router &
is running OSPF as the Routing Protocol. Does the Loopback Interface
have any role to play if both the Serial Interfaces goes down(Line
In article <firstname.lastname@example.org>,
Sabya <email@example.com> wrote:
:Can anybody help me in the following subject?
:Situation 1. Router 1 (2500 series) have 2 Serial Interface connected
:to 2 Branche...Loopback Interface
I'm running a slave kerberos KDC on my OS X laptop. I need to access
the KDC when the laptop is disconnected from any network, but the KDC
doesn't bind to the loopback interface, and I can't seem to setup a
dummy interface in OS X. OS X shuts down any interface on which it
can't detect a link. How can I force the KDC to bind to the loopback
Kerberos mailing list Kerberos@mit.edu
>>>>> "ms419" == ms419 <ms419@...interface to interface
Can I write a program to read packet from one interface and output
packet to another interface?
I wonder if os identify the two IP belong to interface in local
machine, transmitting the packet in IP layer,and no packet goes out
Is it possible to happen?
In article <firstname.lastname@example.org>,
email@example.com (Joseph) wrote:
> Can I write a program to read packet from one interface and output
> packet to another interface?
If you can write a program to read from one interface, and you can write
a program to write to the other interface, wh...loopback interface
Is it possible to create many loopback interfaces (as in Cisco
routers) and get different statistics for these interfaces ?
As an exercise I am trying to implement a very simple packet-loss measurement
tool (copying the approach in Sting: a TCP-based Network Measurement Tool by
Stefan Savage). I am sending a padded HTTP GET request as a sequence of TCP
packets with 1 byte of payload to various web servers and watching the acks
coming back. I pause for 1 second between sending each TCP packet. I have two
1. I am not seeing any packet loss. Am I getting lucky or is the size of the
packet (1 byte payload) somehow not big enough to encourage packet loss?
2. Some web servers are happy ...Packet loss
Please, could anyone of you tell me why packet loss happens in a
computer network? Need to know when and why a packet is rejected and
disappears, and what takes that decision. I really need a deep
explanation or a source where I can dig in. Being quite new in this
subject, I have not found a clear explanation to this problem. Thanks
-----BEGIN PGP SIGNED MESSAGE-----
| Please, could anyone of you tell me why packet loss happens in a
| computer network?
Sunspot activity, backhoes, software bugs, firewalls, oxydation on
conn...problem with ethernet loopback test using loopback plug/stub: receiving socket not seeing packet.
we are writing socket application to send UDP packets out from eth1
and loop it back to
the same interface using loopback stub to verify the hardware without
devices/ports. The sending and receiving port are the same.
our target machine has eth0 configured as 15.6.xx.xx and eth1
configured as 18.104.22.168.
the listening socket is listing on all ip.
When we looked at the packet in the tx code of the driver, we have
observed that the packet passed down from the ip stack has the same
MAC address for both source and destination. Also when packet is
returning, its ip source and...loopback interface / VPN
I set up my router 877 to use EzVPN/xauth to connect to the office
Whenever it succeeds in making a VPN connection ( for testing, I do it
many times ) the config shows another line of interface loopbackN.
Right now it shows :
ip address 192.168.235.114 255.255.255.255
ip address 192.168.235.118 255.255.255.255
ip address 192.168.235.119 255.255.255.255
ip address 192.168.235.131 255.255.255.255
Can this cause any problem if I just let them there ? Or do I have to
clear the old ones ? In the...Network packet loss
I'm having trouble with a K570 I've got in my garage. I want to access
the K box from a PC inside the house. So I came up with the idea to
link the systems via the wireless network I have in the house, a 2Wire
router/modem -1000HG, via SBC. I got a Motorola bridge, WE800G and
setup the wireless connection successfully. I�m able to ping the bridge
from a PC in the house, no problem.
Here�s the problem, while I can ping the bridge with 0 packet loss, if I
try to ping the 9000 (which is Cat 5 Ethernet connected to the bridge) I
get a typically 75% failure (only 4 tries from ...Winsock + Loopback Interface
While addressing a bug in the implementation of Tcl sockets under
I'm observing strange things only on the Windows loopback interface.
These strange things seem to be related to TCP FIN packets.
However, the only tool I've found so far to snoop the loopback is
CommView, and it seems to be unable to see the FIN flag on the
loopback (even for a bug-free, normally terminated socket). FINs are
correctly reported on non-loopback.
Question 1: do you know of another tool, ...some commands about loss packet
On the c 4500 is command:
show platform cpu packet statistics all
Now i have c 4006 and i can't find this or similar command. I'd like to now
about loss packet when the cpu is overhead or near overhead and when the
proces packet forwardig is big how many packets is droped. The command sh
proc cpu is not enough, i think...
If you are running CEF, then see
sh...50% packet loss ?
What does it meen when my ping reply is !.!.!.!.!.!.!. for one IP-address.
In LAN the ping reply is !!!!!!!! but from another network only every other
packet is comming back.
Check for static route to non-existing or dead gateway. For example, if you
have two static routes with the same metrics to the same destination, router
will try to do a load-balancing between gateways, and if one is down, you
will get every other packet lost.
CCNP, CCDP, CCSP, Cisco Voice, MCSE W2K, MCSE+I, Security+, etc.
CCIE R&S (in progress), CCIE Voice (in progress)
-----...TCP_NODELAY at loopback interface
the WINCE 5.0 Winsock socket option TCP_NODELAY should control, if the Nagle
algorithm is activated or not. The nagle alrorithm should delay transmission
of short segments and send one segments, that contains all the short chunks.
1) Does the Nagel algorithm also works for the Loopback interface 127.0.0.1?
How is the term "data already in flight" to be read?
2) The function getsockopt returns the current value of the winsock option.
What does it mean, when I get the result 8 (eight), when I have set the
v...Freeswan and loopback interface
I'm trying to solve without success the following problem:
I've got a linux appliance behind an adsl router.
I user a private /30 to connect the router to the appliance
to save IP addresses. The router does only routing no nat.
| lo:1 public ip1 int adsl: public ip2
|----Linux appliance---------------ADSL router--------
| eth0:192.168.0.1 eth:192.168.0.2
private net 10.0.0.0/16
In this way I use only 2 pubblic IP addresses.
Don't tell me to use an ADSL interface on the appliance:
I want to set up a IPSec ...System Packet Interface?
I am doing a project on a 10GB Ethernet.
I am going to use a FPGA with a 10Gb Ethernet Mac Core.
If I use a NIOS II, it's not necessary for me to purchase a developmen
board supporting the SPI (System Packet Interface)?
This interface is used between a FPGA and NPU.
On Fri, 24 Feb 2006 09:11:02 -0600, "freechip" <firstname.lastname@example.org>
>I am doing a project on a 10GB Ethernet.
>I am going to use a FPGA with a 10Gb Ethernet Mac Core.
>If I use a NIOS II, it's not necessary for me to purchase a development
>board supporting...Multiplexing and packet loss
I have a 1gbit (1000BaseZX) link between two sites that's, due to
large number of small packets, have alot of buffer related packet loss
in one direction. A solution I'm planning to implement is CWDM on this
link and team at least four interfaces into an etherchannel. I'm
however unsure if this will actually solve any of the packer loss
problems. In theory four interface buffers should be better than one
but I wounder if anyone have any real world data on this. Will a CWDM
etherchannel only move the buffer problems from the interface to the
Fredrik...6506 loopback interface
We have a single 6506 which we will replace with two 6506 in HSRP
redundancy mode. Until now we don't have a loopback interface configured
on the 6506. Most management articles advise the use of the loopback
interface so we want to configure it on both the 6506's. What we can't
find, is what kind of address to put on both machines. Loopback
addresses seem to be host adresses but how are they related to each other ?
If we give router A address x.x.y.1, can we give router B address
x.x.y.2 or do we need to give it x.x.Z.1 so i need a separate subnet for
each interface ? If one...1841 Packet loss
Here is the situation,
1841 with connected 100Mbs LAN and 100Mbs WAN (capped at 20Mbs). It's
used to send VOIP calls. THe LAN side is connected to a VOIP GW
sending via calls 16T1s, so 368 simulataneous calls.
When all 16 T1s are used we gets packet loss (between point to point's
on the WAN link) and reports of garbled calls, if we only use 8 T1s
all is well.
Here is a snapshot of the Traffic on the links..
30 second input rate 2003000 bits/sec, 2734 packets/sec
30 second output rate 3545000 bits/sec, 5000 packets/sec
So including both FE's that about 16000pps... lets 20kp...Redirect packets between interfaces.
mam sobie taki problem, ze chce, aby czesc ruchu (glownie P2P)
rutowana byla przez interfejs ppp1. "Glowniejszy" defaultroute
jest na ppp0, na ppp1 nie dziala traceroute (ktos ma pomysl,
czemu?), ale polaczyc sie da, ustawiajac recznie regulke
ip route dla siakiegos ip.
I have the following problem. I read iptables tutorials,
LARTC, without any clue for solution.
Anyway, I have two interfaces:
tun0 is reliable, fast, but has most P2P blocked on the other side
ppp0 is slower, but is totally non-firewalled.
I would like to use L7 to classify packets as P2P traffic and then