Subject: ISDN - first TCP connection fails
To: None <>
From: Ingolf Steinbach <>
List: tech-net
Date: 03/08/2002 18:36:52

on my NetBSD 1.5.3_ALPHA (i386) system with i4b 00.96.0
I have tried to set up the ISDN connection according to
(I was told that the i4b in -current is the same as 00.96.0,
so this description should work.)

The network configuration looks like this:
# ifconfig isp0
        inet -> netmask 0xff000000
        inet6 fe80::200:c0ff:fe20:6b63%isp0 -> :: prefixlen 64 scopeid 0x8
# netstat -nr -f inet
Routing tables

Destination        Gateway            Flags     Refs     Use    Mtu  Interface
default              US          0     5062   1500  isp0              UH          0        0   
1500  isp0
127                UGRS        0        0  33228  lo0          UH          2        2  33228  lo0
192.168.2          link#1             UC          1        0   1500  we1        00:00:1c:d3:c3:13  UHLc        6    32887   1500  we1

This is the result of
    ifconfig_isp0="inet link1 down"
    defaultroute=" -iface"
in /etc/rc.conf.

No ipnat rules are installed, and ipf is disabled. But both are
enabled in the kernel config file (in case it matters).

Let's now try to connect to an external host (
% telnet -N
telnet: Unable to connect to remote host: Can't assign requested address

The first try to connect always fails: If I use tcpdump on isp0,
there is just some non-IP traffic (probably related to ppp).
The second try of the above telnet will usually succeed.

Am I missing something? Is this normal behaviour? How can I fix