Networking on wporter.org

Flash Mellanox ConnectX-3 Pro firmware (CX314A-BCCT to CX354A-FCCT)

Sat, 31 Jan 2026 19:00:00 +0000

Introduction

The ConnectX-3 Pro (MT27520) was sold in a few different configurations (e.g., dual SFP+, QSFP+, dual QSFP+, Ethernet only, Infiniband and Ethernet). However, all the ASICs are the same, so you can easily cross-flash them (It’s possible to flash VPI firmware to an Ethernet card if you want to unlock Infiniband.)

You can also typically flash OEM cards to stock Mellanox firmware with little hassle.

The most recent batch I purchased are CX314 Ethernet-only cards (about $10 each) so I figure I’ll crossflash them to the VPI cards before pressing them into service as IB HCAs (for that sweet, sweet RDMA).

Configuring LACP bonds & VLAN bridges with nmcli

Sat, 03 May 2025 18:30:00 +0000

LACP is awesome if you’re not terminating L3 on your servers. It’s also super easy to configure bonds with NetworkManager.

Configuring LACP (802.3ad) bonds with nmcli

To configure a bond, you’ll need to:

Create the bond interface
Assign connections as slaves to the bond
Bring the bond up

This is pretty simple:

[liam@t3 ~]$ nmcli con add type bond con-name bond0 ifname bond0 bond.options "mode=802.3ad"

This will create a bond0 device, and a bond0 connection - you can see them in the output of nmcli con or nmcli dev:

Cisco 3850 ignoring startup-config on boot, config-register stuck at 0x142

Sat, 22 Feb 2025 10:12:59 +0000

Problem

This appears to be Cisco bug CSCui54490.

After a write erase (or, I believe, a format flash: or a PW recovery in this case?) a 3850 will ignore its startup-config and always boot a blank configuration.

My switch is running IOS-XE 16.12.11 (Gibraltar), date Sun 31-Mar-24 12:30 (a minor version behind at the time of writing), though this seems to be a long-standing issue.

show version output suggests config register is 0x142.

JNCIA lab: simple route redistribution in Junos

Mon, 06 Jan 2025 10:10:10 +0000

Topology:

Images used:

IOSv L2 15.2 (as dumb hosts) IOSv L3 15.9 JOSv (vMX) 23.2R1.15

Configure interfaces’ addressing as shown.

Configure a mesh of four routers in an OSPF area: JR1, JR2, JR3 and CR1

OSPF should advertise these four routers’ loopback addresses. Any interface not facing another OSPF router should be declared passive.

Configure RIP on JR3 and JR4. Modify the default export policy so they can talk. Redistribute the RIP routes to 169.254.0.16/30 and 192.51.100.0/24 into the OSPF area. Redistribute JR3’s OSPF routes into RIP on JR3 and JR4. Make sure CS1 can ping any of the loopback addresses in the topology with just a default route configured to JR4.