eBGP, TTL and Connected-Check

It is well known that eBGP packets default to having a Time to Live (TTL) value of 1. This has caused confusion for many network practitioners who wish to run eBGP between loopback addresses of directly connected routers. This misunderstanding sometimes leads to ebgp-multihop being configured when it is not necessary. This also gave me

Dead Peer Detection in Multipath Networks

When I learned about Dead Peer Detection, I assumed it to be some generic IPsec keepalive and didn’t put much thought into it. A few weeks ago, I became more interested in DPD and started reading RFC 3706. I learned that DPD is a feature of IKE and I started considering how the protocol may

Next Hop Recursive-Looped

In this morning’s lab exercise I intentionally designed and configured a network to cause recursively looped routing lookups. When I started the experiment, I did not know this is the term for this condition. I simply wanted to see what would happen if the route to the destination was also the route to the next

OSPF Autoconfiguration with Python

I find that sometimes when I want to lab up a specific scenario I have to do the same “router ospf 1234” and “network 198.51.blah.blah area blah” commands over and over just to get basic routing configured. Awhile ago I wrote an EIGRP auto configuration script but at that time I didn’t know about the

Soft Reconfiguration Inbound

This morning I set up an eBGP session between routers with a switch in the middle configured for SPAN. The SPAN session sent the output to my laptop for Wireshark analysis. Of course, I would need prefixes in BGP to have something to observe. I took inspiration from Free Range Routing’s sharpd feature and wrote

Humble Beginnings

For my first post I thought I’d share my home office setup and lab environment. My daily driver PC is an Asus Zenbook with an 11th gen i7, 16GB of memory, an NVIDIA GTX 1650 graphics card, and a 500GB SSD. I’m choosing to stay with a laptop for now so I can easily swap