Linux

Linux IPv6 routing table max_size badly dimensioned compared to IPv4

http://marc.info/?l=linux-netdev&m=139352943109400&w=2

Hi everybody,

Today, a PowerDNS (open source dns, www.powerdns.com) deployment ran into
trouble with large amounts of IPv6 users. It appears a large telco 'flicked
the switch'. We had around 8000 DNS queries/s over IPv6, and everything
slowed to a crawl. 100% CPU utilization, most of it in the kernel. The same
amount of queries over IPv4 causes no problems.

Ubuntu 13.04 client doesn't get IPv6 address at boot time

Problem description: an Ubuntu client doesn't configure the IPv6 address at boot time. But running manually "dhclient -6" works. dmesg reports:

[   11.997321] type=1400 audit(1372427393.005:35): apparmor="DENIED" operation="open" parent=1053 profile="/sbin/dhclient" name="/var/lib/NetworkManager/dhclient6-eth0.conf" pid=1765 comm="dhclient" requested_mask="r" denied_mask="r" fsuid=0 ouid=0

 

SLC5 and SLC6 may have IPv6 disabled

  • SLC5 may have the ipv6 module disabled. Please edit the file /etc/modprobe.conf and remove the lines disabling ipv6 (#alias ipv6 off, #options ipv6 disable=1); then reboot.
  • SLC6 may have the ipv6 module disabled. Please edit the file /etc/modprobe.d/ipv6.conf and remove the lines disabling ipv6 (# options ipv6 disable=1); edit the file /etc/avahi/avahi-daemon.conf and set use-ipv6=yes; then reboot.

Manually configure static IPv6 address in SLCx

Add these lines to /etc/sysconfig/network-scripts/ifcfg-eth0
IPV6INIT=yes
IPV6ADDR=2001:1458:E00C::63/64

Add these lines to /etc/sysconfig/network
NETWORKING_IPV6=yes
IPV6_DEFAULTGW=2001:1458:E00C::1

 

  • WARNING: SLC5 images have the ipv6 module disabled. Please edit the file /etc/modprobe.conf and remove the lines which disable ipv6 (#alias ipv6 off, #options ipv6 disable=1); then reboot.

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