Layer 2 Traceroute - Another Cisco Baby To Help Operations Guys

Well it's been a while or probably years ago I wanted to talk and write about this interesting Cisco baby called " Layer 2 Traceroute ". I called it Cisco Baby because it requires Cisco Discovery Protocol (CDP) to be enabled in order to function.

Now Idea is simple, In traditional L2 Campus or Enterprise Network our Network Operations Team keep getting several requests such us tracing user port and change it's vlan to something else or maybe a troubleshooting call where we need to identify source port of user or server etc. The traditional approach usually was to first hop on to switch hosting SVI for given VLAN , Figure out Layer 2 address for given IP (User/Server IP) and do reverse engineering by tracing that Layer 2 Mac Address hop by hop until we hit the user port configured in access vlan or Server that might be using trunking in a virtualized network.

Here is a quick example of traditional approach:

Now Here is how this wonderful IOS tool helps you trace quickly

Further Readings:

http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst6500/ios/12-2SX/configuration/guide/book/l2trace.html

http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3550/software/release/12-1_13_ea1/command/reference/3550cr/cli3.pdf

http://packetpushers.net/tracing-a-layer-2-path-on-cisco-nexus-switches/


HTH...
Deepak Arora
Evil CCIE

OTV Multicast-Mode Configuration Example Using OTV On Stick Design - OTV Series Part 3

 

Configuration Template Used In Demo:

DC1-N7K-1
+++++++++

!
en
!
conf t
!
vlan 100
 name OTV-SITE-VLAN
vlan 200
 name OTV-EXTEND-VLAN
!
int lo0
 ip add 11.11.11.11/32
 exit
!
int e1/7
 ip add 1.1.1.1 255.255.255.0
 no sh
 exit
!
int e1/5
 switchport
 switchport mode trunk
 switchport trunk allowed vlan 100,200
 no sh
 exit
!
feature interface
!
feature pim
!
int vlan 200
 ip add 200.0.0.1/24
 no sh
 exit
!
int e1/1,e1/7
 ip igmp ver 2
 ip pim sp
 exit
!
ip pim rp-add 30.0.0.1
!


DC2-N7K-1
+++++++++

!
en
!
conf t
!
vlan 100
 name OTV-SITE-VLAN
vlan 200
 name OTV-EXTEND-VLAN
!
int lo0
 ip add 22.22.22.21/32
 exit
!
int e1/14
 ip add 2.2.2.1 255.255.255.0
 no sh
 exit
!
int e1/12
 switchport
 switchport mode trunk
 switchport trunk allowed vlan 100,200
 no sh
 exit
!
feature interface
!
feature pim
!
int vlan 200
 ip add 200.0.0.2/24
 no sh
 exit
!
int e1/10,e1/14
 ip igmp ver 2
 ip pim sp
 exit
!
ip pim rp-add 30.0.0.1
!



DC1-N7K-2
+++++++++

!
en
!
conf t
!
vlan 100
 name OTV-SITE-VLAN
vlan 200
 name OTV-EXTEND-VLAN
!
int lo0
 ip add 111.111.111.111/32
 exit
!
feature otv
!
int e1/11
 ip add 1.1.1.2 255.255.255.0
 ip igmp ver 3
 no sh
 exit
!
int e1/9
 sw
 sw mode tr
 sw tr all vlan 100,200
 no sh
 exit
!
otv site-vlan 100
 exit
!
otv site-iden 0x001
!
int overlay 1
 otv join-interface e1/11
 otv control-group 235.0.0.1
 otv data-group 232.0.0.0/4
 otv extend-vlan 200
 no sh
exit
!


DC2-N7K-1
+++++++++
!
vlan 100
 name OTV-SITE-VLAN
vlan 200
 name OTV-EXTEND-VLAN
!
int lo0
 ip add 222.222.222.222/32
 exit
!
feature otv
!
int e1/20
 ip add 2.2.2.2 255.255.255.0
 no sh
 ip igmp ver 3
 no sh
 exit
!
int e1/18
 sw
 sw mode tr
 sw tr all vlan 100,200
 no sh
 exit
!
otv site-vlan 100
 exit
!
otv site-iden 0x002
!
int overlay 1
 otv join-interface e1/20
 otv control-group 235.0.0.1
 otv data-group 232.0.0.0/4
 otv extend-vlan 200
 no sh
exit
!

Further Readings:

http://routing-bits.com/2011/06/16/cisco-otv-part-i/

http://routing-bits.com/2011/06/28/cisco-otv-part-ii/

http://routing-bits.com/2011/07/06/cisco-otv-part-iii/

http://blog.ine.com/2010/02/15/what-is-overlay-transport-virtualization/

http://blog.ine.com/2012/08/17/otv-decoded-a-fancy-gre-tunnel/

http://www.cisco.com/en/US/docs/solutions/Enterprise/Data_Center/DCI/5.0/OTVmulticast.pdf

http://www.cisco.com/en/US/docs/solutions/Enterprise/Data_Center/DCI/whitepaper/DCI3_OTV_Intro_WP.pdf

http://www.netcraftsmen.net/user-group/c-mug-archive/904-overlay-transport-virtualization.html

http://www.netcraftsmen.net/blogs/entry/spanning-layer-2-between-data-centers.html

http://www.netcraftsmen.net/blogs/entry/understanding-layer-2-over-layer-3-part-1.html

http://www.netcraftsmen.net/blogs/entry/understanding-layer-2-over-layer-3-part-2.html

http://www.netcraftsmen.net/blogs/entry/exploiting-layer-2-over-layer-3.html

http://www.netcraftsmen.net/blogs/entry/otv-optimal-routing.html

http://www.netcraftsmen.net/blogs/entry/cisco-overlay-transport-virtualization-otv.html

http://www.netcraftsmen.net/blogs/entry/data-center-l2-interconnect-and-failover.html

http://www.netcraftsmen.net/blogs/entry/designing-an-otv-deployment.html

http://www.netcraftsmen.net/blogs/entry/otv-and-dci-require-stp-defenses.html

http://packetpushers.net/pq-show-24-cisco-otv-deep-dive-part-1/

http://packetpushers.net/pq-show-25-cisco-otv-deep-dive-part-2/

http://packetpushers.net/show-155-integrating-otv-fabricpath-lisp-sponsored/

http://packetpushers.net/cisco-otv-101-legacy-multicast-mode-mac-learning-process-walk/

http://packetpushers.net/anycast-hsrp-design-considerations/

HTH...
Deepak Arora
Evil CCIE

OTV Unicast-Mode Configuration Example Using OTV On Stick Design - OTV Series Part 2

Note: DC1-N7K-2 Is Playing Role Of OTV Unicast Adj. Server

Configuration Template Used In Demo:

Getting Infrastructure Ready
############################

DC1-N7K-1
+++++++++

!
en
!
conf t
!
feature interface-vlan
!
vlan 100
 name OTV-SITE-VLAN
 exit
!
vlan 200
 name OTV-EXTEND-VLAN
 exit
!
int vlan 200
 ip add 200.0.0.1/24
 no sh
 exit
!
int e1/5
 switchport
 switchport mode trunk
 switchport trunk allowed vlan 100,200
 no sh
 exit
!
int e1/7
 ip add 1.1.1.1/24
 < Enable Routing Of Your Choice >
 no sh
 exit
!
int e1/1
 ip add 10.1.13.3/24
 < Enable Routing Of Your Choice >
 no sh
 exit
!

DC2-N7K-1
+++++++++

!
en
!
conf t
!
feature interface-vlan
!
vlan 100
 name OTV-SITE-VLAN
 exit
!
vlan 200
 name OTV-EXTEND-VLAN
 exit
!
int vlan 200
 ip add 200.0.0.2/24
 no sh
 exit
!
int e1/12
 switchport
 switchport mode trunk
 switchport trunk allowed vlan 100,200
 no sh
 exit
!
int e1/14
 ip add 2.2.2.1/24
 < Enable Routing Of Your Choice >
 no sh
 exit
!
int e1/10
 ip add 10.1.23.3/24
 < Enable Routing Of Your Choice >
 no sh
 exit
!


DC1-N7K-2
+++++++++

!
en
!
conf t
!
vlan 100
 name OTV-SITE-VLAN
 exit
!
vlan 200
 name OTV-EXTEND-VLAN
 exit
!
int e1/9
 des "OTV-INTERNAL-INTERFACE"
 switchport
 switchport mode trunk
 switchport trunk allowed vlan 100,200
 no sh
 exit
!
int e1/11
 des "OTV-JOIN-INTERFACE"
 ip add 1.1.1.2/24
 < Enable Routing Of Your Choice >
 no sh
 exit
!


DC2-N7K-2
+++++++++

!
en
!
conf t
!
vlan 100
 name OTV-SITE-VLAN
 exit
!
vlan 200
 name OTV-EXTEND-VLAN
 exit
!
int e1/18
 des "OTV-INTERNAL-INTERFACE"
 switchport
 switchport mode trunk
 switchport trunk allowed vlan 100,200
 no sh
 exit
!
int e1/11
 des "OTV-JOIN-INTERFACE"
 ip add 2.2.2.2/24
 < Enable Routing Of Your Choice >
 no sh
 exit
!

****************************************

OTV Configurations
##################


DC1-N7K-2
+++++++++

!
en
!
conf t
!
feature otv
!
otv site-vlan 100
 exit
!
otv site-identifier 0x01
!
int overlay 1
 otv join-interface e1/11
 otv adjacency-server unicast-only
 otv extend-vlan 200
 no sh
 exit
!


DC2-N7K-2
+++++++++

!
en
!
conf t
!
feature otv
!
otv site-vlan 100
 exit
!
otv site-identifier 0x02
!
int overlay 1
 otv join-interface e1/20
 otv use-adjacency-server 1.1.1.2 unicast-only
 otv extend-vlan 200
 no sh
 exit
!

Further Readings:

http://www.cisco.com/en/US/docs/solutions/Enterprise/Data_Center/DCI/whitepaper/DCI3_OTV_Intro_WP.pdf

HTH...
Deepak Arora
Evil CCIE

How To Bring Old "wr" Command Into Cisco Nexus To Save Configs - Quick Tip

Well I always use "wr" command short for "write" onto Cisco devices to save configurations. I am just too much use to with this syntax that I even don't remember when I used other command " copy run start" last time. :)

On the flip side Cisco Nexus Series platforms don't have "wr" command.

Well the way you can solve this problem is by creating an ALIAS for "copy run start" command and it should be helpful for Operations/Support Teams as well.

In Global configuration mode run the following command:

"cli alias name wr copy running-config startup-config" 

HTH....
Deepak Arora
Evil CCIE

Free CCNA Data Center Video Training - @ Cisco Learning Network

In case you guys haven't noticed this. Cisco Learning Network is offering CCNA Data Center Video Training in free. Most of the sessions were ran by Robert Burns which is CCIE Data Center. Below are access details:

https://learningnetwork.cisco.com/docs/DOC-17214

https://learningnetwork.cisco.com/community/learning_center/recorded_tech_seminars

HTH...
Deepak Arora
Evil CCIE