Common errdisable recovery Commands

errdisable recovery cause udld
errdisable recovery cause bpduguard
errdisable recovery cause security-violation
errdisable recovery cause channel-misconfig
errdisable recovery cause pagp-flap
errdisable recovery cause dtp-flap
errdisable recovery cause link-flap
errdisable recovery cause gbic-invalid
errdisable recovery cause psecure-violation
errdisable recovery cause dhcp-rate-limit
errdisable recovery cause unicast-flood
errdisable recovery cause vmps
errdisable recovery cause storm-control
errdisable recovery cause arp-inspection
errdisable recovery interval 360

Cisco 6500 VSS - convert config commands

Switch -A 

conf t
 switch virtual domain 10
 switch 1


int port-channel 1
 switchport
 switch virtual link 1
 no shut
 exit

int range Te1/1 - 2
 switchport mode trunk
 channel-group 1 mode on


switch convert mode virtual
++++++++++++++++++++++++++++++
Switch -B

conf t
 switch virtual domain 10
 switch 2

int port-channel 2
 switchport
 switch virtual link 2
 no shut
 exit

int range Te1/1 - 2
 switchport mode trunk
 channel-group 2 mode on

switch convert mode virtual

Useful Cisco Network devices Show commands to capture info before migrations .

ter len 0 

show run 
show ip int brief
show int descr
show interface status
show vtp status
show vlan brief
show int trunk
show etherchannel summary
show errdisable recovery
show errdisable detect
show interfaces stats
show interfaces counters
show interfaces switchport
show interfaces transceiver
show spanning-tree summary
show spanning-tree root
show spanning-tree blockedports 
show spanning-tree active detail
show spanning-tree port-priority
show spanning-tree summary totals
show spanning-tree mst configuration
show spanning-tree active
show spanning-tree bridge
show spanning-tree brief
show spanning-tree detail
show spanning-tree interface
show spanning-tree vlan
show ip protocol
show ip eigrp neighbors
show ip eigrp neighbors detail
show ip eigrp interfaces
show ip eigrp topology
show ip eigrp traffic
show ip route summary
show ip route
show ip masks
show standby brief
show monitor session all 
show switch virtual
show switch virtual link
show switch virtual dual-active summary
show switch virtual redundancy
show switch virtual role
show cdp neighbor
show cdp neighbor detail 
show ver
show inventory
show module
show power
show ip arp
show env all

Cisco - Nexus vPC Config commands .

feature vpc

interface Ethernet1/48
  description peer-keepalive
  vrf member peer-keepalive
  ip address 10.19.1.161/30
  no shutdown

interface port-channel1
  switchport
  switchport mode fabricpath
  vpc peer-link


interface Ethernet1/1
  description peer-link to Other Switch
  switchport
  channel-group 1 mode active
  no shutdown 
  
interface Ethernet2/1
  description peer-link to Other Switch 
  switchport
  channel-group 1 mode active
  no shutdown
  

vpc domain 1
  peer-switch
  role priority 2000
  system-priority 100
  peer-keepalive destination 10.19.1.161 source 10.19.1.162 vrf peer-keepalive
  peer-gateway

====================

switch# sh vpc brief 

Legend:
                (*) - local vPC is down, forwarding via vPC peer-link

vPC domain id                     : 1   
vPC+ switch id                    : 1
Peer status                       : peer adjacency formed ok      
vPC keep-alive status             : peer is alive                 
vPC fabricpath status             : peer is reachable through fabricpath
Configuration consistency status  : success 
Per-vlan consistency status       : success                       
Type-2 consistency status         : success 
vPC role                          : primary                       
Number of vPCs configured         : 64  
Peer Gateway                      : Enabled
Peer gateway excluded VLANs       : -
Dual-active excluded VLANs        : -
Graceful Consistency Check        : Enabled
Auto-recovery status              : Enabled (timeout = 240 seconds)
Fabricpath load balancing         : Disabled
Port Channel Limit                : limit to 244

vPC Peer-link status
---------------------------------------------------------------------
id   Port   Status Active vlans    
--   ----   ------ --------------------------------------------------
1    Po1    up     30-32                  

vPC status
-------------------------------------------------------------------------------
id   Port      Status Consistency Reason           Active vlans  vPC+ Attribute
--   ----      ------ ----------- ------           ------------  --------------

101  Po101     up     success     success          30-32        1.11.65535   

Cisco Terminal Server Config template

!
hostname Terminal-server-Router
!
boot-start-marker
boot-end-marker
!

!
no aaa new-model

!
ip domain name << your domain name >>
ip host Device-1 2003 172.21.1.1
ip host Device-2 2004 172.21.1.1
ip host Device-3 2005 172.21.1.1
ip host Device-4 2015 172.21.1.1
ip host Device-5 2007 172.21.1.1
ip host Device-6 2008 172.21.1.1
ip host Device-7 2009 172.21.1.1
ip host Device-8 2010 172.21.1.1
 <<< These Commands continues as per no of serial lines in your device >>>
!
!
!
username <<-->> privilege 15 password 7 <<<-->>>
!
!
!
!
!
!
!
interface Loopback0
 ip address 172.21.1.1 255.0.0.0
!

interface GigabitEthernet0/0
 description *** Uplink to Mgmt Switch ***
 ip address X.X.X.X Y.Y.Y.Y --> IP address to acees the terminal server router
 duplex auto
 speed auto
!
interface GigabitEthernet0/1
 no ip address
 shutdown
 duplex auto
 speed auto
!
ip forward-protocol nd
!
no ip http server
no ip http secure-server
!
ip route 0.0.0.0 0.0.0.0 Z.Z.Z.Z --> Default gateway of the terminal server router
!
!
line con 0
 login local
line aux 0
line 2
 no activation-character
 no exec
 transport preferred none
 transport output pad telnet rlogin lapb-ta mop udptn v120 ssh
 stopbits 1
line 0/0/0 0/0/15
 exec-timeout 0 0
 no exec
 transport input telnet
 transport output none
 stopbits 1
 flowcontrol hardware
line vty 0 4
 login local
 transport input telnet
 transport output telnet ssh
line vty 5 15
 login local
 transport input telnet
 transport output telnet ssh

MTU on Cisco Devices

L2 switched frames that exceed the MTU configured on the switch are dropped since fragmentation is a function of L3 routing. Port will not accept the bigger frames and it can not tell the server to do the fragmentation .

MTU command on the SVI affects the MTU size of all packets including IP. IP MTU only affects the MTU of IP packets.

On platforms where the 'system mtu routing' is available, it only applies to L3 interfaces. L3 routed frames that need to be fragmented are software switched and most switches today forward traffic at line rate so it would be bad design if L3 traffic gets fragmented on the switch.

'system mtu' affects the MTU of all the interfaces on the switch.Its a global command and impacts the over all traffic on all the interfaces . Based on the device models , the platform can support jumbo MTU like upto 9000 , which is required for some none standard traffic like FCoE and devices which can generate bigger frames for bulk of data transfer .

spanning tree protocol, Radia Perlman Poem

The inventor of the spanning tree protocol, Radia Perlman, wrote a poem to describe how it works.11 When reading the poem it helps to know that in math terms, a network can be represented as a type of graph called a mesh, and that the goal of the spanning tree protocol is to turn any given network mesh into a tree structure with no loops that spans the entire set of network segments.

I think that I shall never see

A graph more lovely than a tree.

A tree whose crucial property

Is loop-free connectivity.

A tree that must be sure to span

So packets can reach every LAN.

First, the root must be selected.

By ID, it is elected.

Least cost paths from root are traced.

In the tree, these paths are placed.

A mesh is made by folks like me,

Then bridges find a spanning tree.

— Radia Perlman