BFD between IOSXE and IOS XR

I don’t really easily documentary to configure BFD (RFC5880 and you could read precedent blog-post : BFD : Bidirectional Forwarding Detection (RFC5880)) between IOSXE and IOSXR boxes.

Here it comes 🙂



R0# show run | sec bfd 
bfd fast-timers-on-slow-interface
bfd-template single-hop BFD
   interval min-tx 200 min-rx 200 multiplier 3
R0#show run int port-ch 14
Building configuration...

Current configuration : 373 bytes
interface Port-channel14
description *** Vers R1_Be10000 ***
mtu 9202
ip address
ip ospf authentication message-digest
ip ospf message-digest-key 10 md5 7 XXXXXXXXXXXXXXXXXX
ip ospf network point-to-point
ip ospf bfd
ip ospf cost 20000
no negotiation auto
mpls ip
port-channel bfd destination ipv4 BFD



RP/0/RSP0/CPU0:R1#show conf run int be10000
Tue Feb 14 14:49:35.026 CET
interface Bundle-Ether10000
description *** Vers R0_Po14 *** 
bfd mode ietf
bfd address-family ipv4 multiplier 3
bfd address-family ipv4 destination
bfd address-family ipv4 fast-detect
bfd address-family ipv4 minimum-interval 200
mtu 9216
ipv4 address


[FR] — Parce qu’on a tjs des bonnes intentions en début d’année…

J’ai eu de bonnes intentions en début d’années de produire du contenu en Français sur différents sujets réseaux et télécoms de niveau basiques, mais j’avoue que cela s’est vite arrêté.

Le but était de fournir tout en un :

  • Video explicative ;
  • Une fiche d’étude rapide au format cheatsheet ;
  • Un guide de travail ;
  • Un accès à un lab guidé

Bon j’avoue cela prend énormément de temps et d’autres projets personnels sont venus s’intercalés.

Bref autant partagé ce qu’il en reste et amusez-vous bien :

Soyez pas trop durs …

L’accès à la partie Lab est bien évidemment depuis périmé (on peut donner des durées d’utilisation avec pnetlab :)).

A plus,


xrv9k-full, qemu, AMD Ryzen

If as me you have EVE-NG (2.0.3) and lab some Cisco XRV9K-Full on a virtualized box running AMD Ryzen processor, you have probably encountered problem to start the image. After reading lot of website, it seems the answer is change the command line.

My original command line is :

-enable-kvm -smbios type=1,manufacturer="cisco",product=\"Cisco IOS XRv 9000\",uuid=[...] -cpu host

I correct to :

-enable-kvm -smbios type=1,manufacturer="cisco",product="Cisco IOS XRv 9000",uuid=[...] -cpu qemu64,+ssse3,+sse4.1,+sse4.2

IOS, IOS XE and configure … revert timer X

If you are familiar with IOS XR and JunOS, it lacks a rollback to IOS and IOS XE. You can do it with “archive” such as :

  1. Configure where your archive will be stored.
  2. Say to your OS to “archive” at a point
  3. Configure your router with a “revert timer”
  4. Confirm if it is ok for you

Here we go in details now :

  1. Configure where your archive will be stored.
Router# conf t
Router(conf)# archive
Router(conf-archive)# path bootflash:myconfig
Router(conf-archive)# maximum 10
Router(conf-archive)# end
Router# wr

2. Say to your OS to “archive” at a point

Router# archive config 
Router# show archive
The maximum archive configurations allowed is 10.
There are currently 1 archive configurations saved.
The next archive file will be named bootflash:myconfig-<timestamp>-1
 Archive #  Name
   1        bootflash:myconfig-Jan--3-2022-08-34-34.348-CET-0 <- Most Recent

3. Configure your router with a “revert timer”

Router# configure terminal revert timer 1
Router(conf)# Rollback Confirmed Change: Backing up current running config to bootflash:myconfig-Jan--3-2022-08-35-01.511-CET-1

Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#Rollback Confirmed Change: Rollback will begin in one minute.
Enter "configure confirm" if you wish to keep what you've configured

*Jan  3 2022 08:35:01.670 CET: %ARCHIVE_DIFF-5-ROLLBK_CNFMD_CHG_BACKUP: Backing up current running config to bootflash:myconfig-Jan--3-2022-08-35-01.511-CET-1
*Jan  3 2022 08:35:01.670 CET: %ARCHIVE_DIFF-5-ROLLBK_CNFMD_CHG_START_ABSTIMER: User: console(Priv: 15, View: 0): Scheduled to rollback to config bootflash:myconfig-Jan--3-2022-08-35-01.511-CET-1 in 1 minutes
*Jan  3 2022 08:35:01.670 CET: %ARCHIVE_DIFF-5-ROLLBK_CNFMD_CHG_WARNING_ABSTIMER: System will rollback to config bootflash:myconfig-Jan--3-2022-08-35-01.511-CET-1 in one minute. Enter "configure confirm" if you wish to keep what you've configured
Router(conf)# hostname BLAH
[................... WAITING FOR A MINUTE ........................]
Rollback Confirmed Change: rolling to:bootflash:myconfig-Jan--3-2022-08-35-01.511-CET-1

!Pass 1
!List of Rollback Commands:
no hostname BLAH
hostname Router

Total number of passes: 1
Rollback Done

*Jan  3 2022 08:36:01.669 CET: %ARCHIVE_DIFF-5-ROLLBK_CNFMD_CHG_ROLLBACK_START: Start rolling to: bootflash:myconfig-Jan--3-2022-08-35-01.511-CET-1
*Jan  3 07:36:01.722: Rollback:Acquired Configuration lock.

Router(conf) # end

4. Confirm if it is ok for you

If between your “conf t revert time X” and t0+X, you are ok with the configuration you have made, so you can confirm your changes.

Router# configure confirm

That’s it ! Have fun.

FRR Routing v8.0 is out and happy to see SR


For (perhaps) futur projet I read different documentations around Bird, FRR Routing, … and I am really happy to see in FRR Routing v8.0 the new ‘pathd‘ daemon, which implement SR (Segment Routing). It is really cool to see this.

There is others new feature which have been implemented in this release and are major IMHO.

  • TI-LFA for OSPF and IS-IS (great too for SR) ;
  • VRF for OSPFv3 ;
  • EVPN full-implementation.

It is really great work !!!

More information there :

See you soon 🙂

Long long time ago, blog and FreeBSD…

It was a long long timeago I wrote here. ot of things happens to me but I don’t think it is the time and place to explain it.

This post is about a new experience to me : hosting this blog on FreeBSD machine. I am in love with BSD but don’t use it everyday. Networking&Telco is not an professional area where you can use it or your employer allow you to use it. Damn Windows, Teams, … and his egemony.

I will move this blog from Debian to FreeBSD server. I think it will lot of fun. If I have FreeBSD’s tips or remarks I will post it here. By the way I am currently studying for Cisco’s CCNP SPCOR (350-501) exam. Either I will try to give me a kick in the ass to post more technical posts.

Have fun 🙂