MPLS L3VPN Label Swapping Fun with Fish

https://www.networkingwithfish.com/mp...
I suggest going to the above blog and downloading the PDF and the PCAP file and then clicking on the YouTube link. Below is a timeline of the breakdown of the ~25 minute YouTube

Intro and Overview – (Start til 4:33)

MPLS L3VPN (4:34 – 8:04) — MultiProtocol label switching. Big picture. Pic of typical protocols use for advertising labels in a MPLS L3VPN environment – BGP for the inner (vpn) label and LDP for the outer label.

Placement of the Sniffer (8:05 – 9:30)

BGP Labels (9:31 -11:25) — line 81 in the sniffer trace will show 10.100.100.17 (Charlie17) sends an update to Charlie6 that Charlie17 (10.100.100.17) can get to 10.100.100.2 and to use a label (tag) of 20.


Are We Ready? (11:26 – 13:30) Question: If a Ping comes into Charlie6 from R1 to get to 10.100.100.2 – can Charlie6 just push label 20 on it and send it to Charlie7?

LDP Labels (13:31 – 15:28) — looking at the sniffer trace we can see Charlie7 (10.100.100.7) advertising to Charlie6, via their LDP neighbor relationship, that Charlie7 (10.100.100.7) can help Charlie6 get to 10.100.100.17. And to use a label of 23.

Putting It All Together – Time to Follow the Labels. 🙂
Charlie6 Perspective (15:29-17:53)
Charlie7 (17:54 – 19:16)
A Caveat about Charlie16 (19:17 – 20:25)
Charlie16 (20:26 – 21:44)
Charlie17 (21:45 – 22:57)
Wireshark Fun (22:58 to 24:56)- Checking out the sniffer trace to see the MPLS Labels used between Charlie6 and Charlie7 and tweaking wireshark columns