[Sis-SCPS-INTEREST] first transfer - TX collisions
oneth0 interfaces!!
Feighery, Patrick D.
feighery at mitre.org
Thu May 4 09:51:31 EDT 2006
I need to think about the collision question, but to answer your second
question.
When I ported the SCPS gateway to Linux using the tun methods, I had
similar questions about address assignments. Initial I did not assign
any addresses because I did not see any reason to. Guess what, it did
not work. ;-( So I talked to the guys who wrote tun/tap. The answer
they gave me way essentially "The Linux kernel architecture requires
that network addresses are given to network devices, even if they are
never used." So I tried to choose addresses that would not be in most
people's architecture. If you look at the wire, you will never see
these addresses.
Hope this helps.
As for collisions. do you see any collision when the gateway
functionality is turned off. Are you going through a switch, hub, or
crossover, Also check the parameters of the ethernet interface itself
using /sbin/mii-tool in particular make sure the duplex settings are
the same.
Best Regards
Pat
________________________________
From: sis-scps-interest-bounces at mailman.ccsds.org
[mailto:sis-scps-interest-bounces at mailman.ccsds.org] On Behalf Of Dan
Miller
Sent: Wednesday, May 03, 2006 7:14 PM
Cc: SCPS mailing list
Subject: Re: [Sis-SCPS-INTEREST] first transfer - TX collisions
oneth0 interfaces!!
BTW, among the other messages that I see when the gateway
starts up, there are these:
iptables:: ip addr add 10.99.99.1 peer 10.99.99.2 dev tun0
iptables:: ip addr add 10.99.98.1 peer 10.99.98.2 dev tun1
iptables:: ip addr add 10.99.97.1 peer 10.99.97.2 dev tun2
These IP addresses are *not* part of my network, which contains
all 192.168.* and 172.18.* addresses. Do I need to configure
iptables??
also, I have the firewall turned off completely.
Dan
Dan Miller wrote:
Okay, I have a test setup here, with two scps gateways
connected via a simulated satellite connection with 550 msec RT delay
and 3Mbit data rate in each direction. I have a Windows machine with
an ftp server on one side, connected via 100bT ethernet, I have another
Windows machine on the other side, also connected via 100bT.
When I did an ftp transfer without scps, I got about
14KB/sec, as expected. Then I ran gateway on both sides, I'll put the
rfile at end of this message. When I then ran my ftps, I get transfer
rates in the range of 170-230 KB/sec, though max theoretic rate is
384KB/sec. When I look at the ethernet stats, I'm seeing large numbers
of collisions on the eth0 TX interfaces!! An example of this is:
Data from /proc/net/dev:
I/face| RX: bytes packets errors dropped
frame
lo: 2132 22 0 0
0
eth0: 13165300 175305 0 0
0
sit0: 0 0 0 0
0
eth1: 37488909 26821 0 0
0
tun0: 0 0 0 0
0
tun1: 0 0 0 0
0
tun2: 5282011 5240 0 0
0
I/face| TX: bytes packets errors dropped
collisions
lo: 2132 22 0 0
0
eth0: 40068205 33447 0 0
3393
sit0: 0 0 0 0
0
eth1: 1677395 13802 0 37
0
tun0: 48 1 0 0
0
tun1: 64 1 0 0
0
tun2: 5311879 5814 0 0
0
These collisions are present on *both* gateways; eth0
is my real ethernet interface, while eth1 is my satellite interface.
I tried setting the AIF_RATE to 10,000,000 instead of
100,000,000, but this had no effect. I also tried different AIF buffer
sizes, from 32768 to 256000, but this had no effect either...
Does anyone have any idea what I'm doing wrong here??
I'm seeing a message in the system log on each gateway,
saying:
kernel: tun: Universal TUN/TAP device driver, 1.6
kernel: tun: (C) 1999-2004 Max Krasnyansky
<maxk at qualcomm.com> <mailto:maxk at qualcomm.com>
ifup: Interface /dev/net/tun is not available
when I start the gateway... is this what is causing my
problem?? Either way, what is it telling me?? the device /dev/net/tun
*is* present, and it's a char device file.
Dan
(amusingly, I also spent a bunch of time carefully
configuring the npIP_NP_File, npPathFile, and npNextHopFile, only to
realize that I didn't compile with --scpsnp=yes (since it was mentioned
in a different doc file). However, I don't *think* that's relevant to
this problem, is it?)
# this rfile is in use on both gateways
# GW Resource File - comments are allowed, starting
with '#'.
# Comments can be anywhere EXCEPT between parameter
values.
# interface A info
AIF_NAME eth0
AIF_RATE 100000000
AIF_BUF 32768
AIF_RBUF 32768
AIF_CC 1
AIF_TCPONLY 1
AIF_MTU 1500
#AIF_TAP_NAME tap0
# interface B info
BIF_NAME eth1
BIF_RATE 3072000
BIF_BUF 450000
BIF_RBUF 450000
BIF_CC 0
BIF_MINRTO 600000
#BIF_TAP_NAME tap1
# IPFW info
C_DIVPORT 52000
C_TAP_REMOTE_ACCESS 1
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