Aussie Broadband pauses IPv6 trial due to Cisco bug

Aussie Broadband has temporarily paused an IPv6 beta trial “due to an ongoing bug” affecting the firmware of Cisco aggregation services routers (ASRs) it uses in its network.

The internet provider said it had been forced to pause the trial after a patch released by Cisco for the bug contained a new bug that then caused an unrelated issue.

Cisco ASRs act as broadband network gateways (BNGs) or access points through which subscribers connect to a broadband network. “When a connection is established between BNG and customer premises equipment (CPE), the subscriber can access the broadband services provided” by an ISP, according to Cisco documentation.

But the ASRs are currently impacted by a firmware bug that “causes the DHCP [Dynamic Host Configuration Protocol] process on the routers to crash, so customers are not able to reauthenticate,” Aussie Broadband said in a customer advisory.

DHCP is used to assign and manage IP addresses in a network.

“This requires a full reboot of the router to fix, and occurs every 10-15 days,” Aussie Broadband said.

The bug has official recognition from Cisco - and is one of five that Aussie Broadband has uncovered in Cisco code over the past 18 months “that have not been discovered previously”.

“The issue is [that] there is a memory leak in the DHCPv6 process that hands out IPv6 addresses to customers who have opted into IPv6,” Aussie Broadband managing director Phillip Britt wrote on Whirlpool.

About 2000 of Aussie Broadband’s 174,000 NBN users are on the native IPv6 open beta, Britt said in a separate post.

Aussie’s problem is those reboots affect all users connected to the internet through that Cisco router, not just those using IPv6, causing stability problems.

In the customer advisory, Aussie Broadband noted that “Cisco has recently released a patch for this bug, however recent attempts to apply this patch brought to light a new issue which was not apparent in testing.”

iTnews understands the fix was installed alongside a service pack that was needed for the patch to install. While it resolved the DHCP issue, it broke point-to-point protocol over Ethernet (PPPoE), which stopped Aussie’s wholesale customers from connecting to the internet.

“So we can either have the DHCPv6 memory leak bug OR the PPPoE bug,” Britt wrote.

The company rolled back the firmware patch to avoid the PPPoE bug, which means the initial memory leak problem remains unresolved.

“We have pushed this new issue back to Cisco, but we will need to disable IPv6 while it is resolved,” Britt wrote.

Britt said that the last patch issued by Cisco had taken around two months to code, providing some indication of when Aussie Broadband might be able to resume the IPv6 beta.