I’m waiting for my copy of “Cisco Digital Network Architecture: Intent-based Networking for the Enterprise (Networking Technology)” to arrive. In the meantime, I glanced at the contents on Amazon. Among the dedications, there is a binary message. Add a bit of Erlang magic and the message is revealed.

Read More → Binary message in Cisco Digital Network Architecture: Intent-based Networking for the Enterprise (Networking Technology)

NBAR2 on Sup8E can assist in blocking BitTorrent. While somewhat useful, BitTorrent is mostly used for downloading pirated movies, and BitTorrent off someone’s ADSL line is usually dead slow. Create a class map and a policy map as shown below, and attach that policy map to your ingress interfaces, and BitTorrent should be blocked. class-map […]

Read More → Using QoS for blocking BitTorrent on Catalyst 4500E Sup8E

The official documentation on Cisco IOS XE for Catalyst 4500E claims this is the syntax for specifying IPv6 RDNSS and DNSSL: Switch(config)# interface Te1/1 Switch(config‑if)# ipv6 nd ra dns server 4::4 Switch(config‑if)# ipv6 nd ra dns search list aaa.cc.com Using IOS XE 3.10.0E, the correct syntax for DNSSL is: Switch(config)# interface Te1/1 Switch(config‑if)# ipv6 nd ra dns server 4::4 Switch(config‑if)# ipv6 nd ra dns‑search‑list domain aaa.cc.com Sadly, the quality of Cisco’s documentation isn’t what it was back in 2006.

Read More → IPv6 RDNSS and DNSSL on Cisco IOS XE

Cisco’s Catalyst 9400 Series introduced this summer do look promising, but it’s still missing a few highlights: Complete support for redundant supervisors; unavailable according to the release notes dated July 31, 2017 The supervisor module (hardware) supports redundancy, but the software does not. The associated route processor redundancy (RPR) and stateful switchover (SSO) features are […]

Read More → Cisco Catalyst 9400 Series

At work we switched from a Cisco Catalyst 3560G to a Catalyst 4500E a few weeks ago. Remember to issue the spanning-tree extend system-id command prior to enabling VTP version 3. During the test period, the Icinga instances logged packet losses of varying degree around the clock when doing ICMPv6 pings.

Read More → Lessons learned on Cisco Catalyst 4500E

I’ve noticed that Cisco VPN Client 5.0.07.0440 tends to fail with “Reason 414: Failed to establish a TCP connection.” on long-running Windows 7 SP1. It’s been going on for years.

Read More → Long-running Windows 7 SP1, Cisco VPN Client 5.0.07.0440, and “Reason 414: Failed to establish a TCP connection”

While reloading a Cisco Catalyst 3560 running IOS 12.2(55)SE the other day, I noticed the switch stopped sending messages to the configured IPv6 enabled syslog host. Nothing appeared in the log files on the syslog host until I manually disabled and reenabled the log statement.

Read More → Logging messages from Cisco IOS 12.2(55)SE to an IPv6 enabled syslog host