Category: Cisco
Anything related to Cisco
Dell PowerSwitch S4048-ON, (rapid-)PVST, port-channels, and VLAN 1
TL;DR, port-channels on the Dells needs portmode hybrid in addition to switchport to enable VLAN 1, and it helps to ignore “invalid” PVST-BPDUs by adding no spanning-tree pvst err-disable cause invalid-pvst-bpdu to the port-channels.
Read More → Dell PowerSwitch S4048-ON, (rapid-)PVST, port-channels, and VLAN 1Switch ports are listed as suspended
If your switch ports are part of a link aggregation group, and those interfaces are listed as suspended, check the LAG configuration on the other end.
Read More → Switch ports are listed as suspendedCisco Catalyst 9600 and fixed wire speeds
If you connect your Cisco Catalyst 9600 to equipment using fixed wire speeds, you may need to issue the speed nonegotiate command on affected switchports.
Read More → Cisco Catalyst 9600 and fixed wire speedsCisco Aironet 3700 Series Access Points and expired Manufacturing Installed Certificates
Sometimes old equipment fails in mysterious ways. This time a whole fleet of Cisco Aironet 3700 Series Access Points disappeared from their controller. The access points have “Manufacturing Installed Certificates” and these certificates will expire sooner or later. In this case, the certificates expired sometime during the weekend.
Read More → Cisco Aironet 3700 Series Access Points and expired Manufacturing Installed CertificatesCisco IOS (XE) and OpenSSH 8.x
OpenSSH marches on and disables old and insecure algorithms. Sadly, Cisco IOS (XE) lags behind. Previously, I could do all scp operations from the cli in the switches. Now, I must do everything from the management station. For now, I can get by if I allow some of the older key exchange (key agreement) algorithms. […]
Read More → Cisco IOS (XE) and OpenSSH 8.xAdding a Cisco Catalyst 2960X switch to a Cisco Catalyst 2960S switch stack
A few things must be done before adding a Cisco Catalyst 2960X switch to a Cisco Catalyst 2960S switch stack. I assume you know your way around Cisco IOS, and already have the necessary hardware components.
Read More → Adding a Cisco Catalyst 2960X switch to a Cisco Catalyst 2960S switch stackiperf3 results between Chelsio T6225-CR and Intel X710-DA4
I ran two iperf3 tests between two hosts using Chelsio T6225-CR and Intel X710-DA4, respectively. Both NICs are connected to the supervisor interfaces on a Sup8E in a Cisco Catalyst 4500E chassis. Wirespeed is 10 Gbit/s.
Read More → iperf3 results between Chelsio T6225-CR and Intel X710-DA4Binary message in Cisco Digital Network Architecture: Intent-based Networking for the Enterprise (Networking Technology)
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)Using QoS for blocking BitTorrent on Catalyst 4500E Sup8E
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 Sup8EIPv6 RDNSS and DNSSL on Cisco IOS XE
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