Problem: After an update of a server to Devuan4/Debian11the switch shuts down the interfaces to the server with status “dcxNoACKi” 48 minutes after the reboot. Discussion: the switch is a Cisco Nexus 5000 switch. It implements “Data Center Bridging Capability Exchange (DCBX)”. The server is a Dell server with X710 Controller 10GbE with i40e drivers. …
Interface down on Cisco Nexus switch with “dcxNoACKi” Read More »
Every Cisco switch has a serial number that shows information about it’s production location and year. As you see this switch is very old and was running very long. Without any issues btw. The serial number here is shown as “Processor board ID”, you might also find “System serial number” or similar. The format is …
There are at least two pieces of software you can update in a Cisco ASR-1001-X. The ROMMON (firmware) and the IOS itself. This router uses “Cisco IOS XE Software”. Which is an IOS process on a Linux kernel as far as I know. Cisco recommends specific ROMMON releases for different generations of software. You can …
Problem: Cisco ASR router is loosing connectivity to its directly attached Ethernet neighbors. In this situation interface status is still up, packets are going in and out on both ends, even IPv6 was still working. The actual problem was that the Cisco ASR was ignoring all ARP responses from its neighbors and the ARP table to this …
ASR-1001-X and IOS-XE is sometimes different and sometimes very similar to classic IOS. Update. You can update, the firmware as usual: # copy http: bootflash: # conf t (config)# boot system flash bootflash:asr1001x-universalk9.03.16.00.S.155-3.S-ext.SPA.bin Show SFP (transceiver) info: # show hw-module interface tenGigabitEthernet 0/0/0 transceiver status # show hw-module interface tenGigabitEthernet 0/0/0 transceiver idprom .. to be continued
Problem: After upgrading an ethernet port to a channel-group, all MLPPP connections fail on a Cisco ASR 1002-X. The log file looks like this: Jul 31 2015 07:04:44.801 CEST: Vi4 PPP: Phase is AUTHENTICATING, Authenticated User Jul 31 2015 07:04:44.801 CEST: Vi4 CHAP: O SUCCESS id 143 len 4 Jul 31 2015 07:04:44.801 CEST: Vi4 …
MLPPP over L2TP over Ethernet Channel Groups on Cisco ASR Read More »
Problem: PPTP from any client to an ASR1002-X Cisco does not work. PPTP Connections starts but in PPP LCP phase the connection fails. Solution: Cisco ASR1002-X with Software IOS-XE 15.3(2)S2 has no PPTP support. You have to take a different Router! Discussion: The weird thing is, that most of the PPTP stack is still configureable and working, …
Problem: You want to know which switch and what port your Linux machine is connected to? Solution: If the switch does CDP (all Cisco switches do), it tells you a lot of information. Tcpdump can capture and show this information. # tcpdump -i eth0 -n -v -s 1500 -c 1 ‘ether[20:2] == 8192’ tcpdump: listening …
I had to update the software of a new Cisco Catalyst 4948 yesterday. As usual I did: copy tftp://<hostname>/<filename> bootflash: conf t boot system flash bootflash:<filename> exit reload But the switch ignored the new software image. During boot it said: Booting first image from bootflash Solution: The config-register was set to 0x2101 right out of …
Cisco routers are capable of different routing protocols and static and connected routes. Every routing protocol engine has its own distance/metric/weight to decide which route is best. When a routing protocol has chosen its best route, the route is entered into the routing table. The routing engine uses an “administrative distance” per routing protocol to …