Idle : There is no relationship, but the router sends out a TCP SYN to the neighbor to get the ball rolling.

Idle (admin) : The neighbor is admined down.

Connect : The router is waiting for the TCP connection to finish.  If the TCP connection finishes, the router sends an open and transitions to OpenSent.  If it times out, it transitions to Active.

Active : The router tries to initiate a TCP connection.  If the TCP connection finishes, the router sends an open and transitions to OpenSent.

OpenSent : The router is waiting for an open to be returned.  If one is received, the router transitions to OpenConfirm.

OpenConfirm : The router is waiting for a keepalive.  If one arrives, the router transitions to Established.

Established : The neighbor relationship is complete and updates are exchanged.

Aaron Conaway

I like to lean my head to the left, hit it with the palm of my right hand, and document what knowledge falls out.

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This is one of those little things in life that make me happy.  Since the active ASA always has the same hostname and IP address, I find it hard to keep track of to which firewall I'm actually connected.  That "configurtions are no long in sync" message you get when you conf t on the standby firewall really irks me.  With the prompt command, I can see which firewall I'm on and in what state it is.

Here are the options you can use.

firewall(config)# prompt ?

configure mode commands/options:
  context   Display the context in the session prompt (multimode only)
  domain    Display the domain in the session prompt
  hostname  Display the hostname in the session prompt
  priority  Display the priority in the session prompt
  state     Display the traffic passing state in the session prompt

Note that the command is similar to the service timestamps in IOS where you can stack options.  I wound up setting my prompts to "hostname priority state" so I can see that information without having to do a show failover.  If you run contexts, I'm sure that would be a good one to include as well.  I imagine adding "domain" may make the prompt too long for use, though.  Heh.

Send any candy hearts questions my way.

Aaron Conaway

I like to lean my head to the left, hit it with the palm of my right hand, and document what knowledge falls out.

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A switch port on a 2960 comes up with a default configuration on VLAN 1.  What happens from the perspective of spanning-tree?

• First, the port comes up on blocking mode.  This is to make sure that loops aren’t created without first listening to the network to see what’s going on.
• Next, if the port may be a root or designated port, the port is moved to the listening state.  In this state, the port can send and receives BPDUs only.  It can’t send traffic, but it can discover the other switches participating in STP.
• After the forwarding delay, the port goes into the learning state.   In this state, the port can send and receive BPDUs as in listening, but it can now receive traffic.  It can’t yet send any.
• After the forwarding delay again, the port goes into the forwarding state.  The port can now send and receive data.

If the port is configured with spanning-tree portfast, the mode goes from blocking directly to forwarding without going through these steps.  Obviously you don’t want a switch plugged into a port configured for portfast since you may wind up with a loop.

Here’s the debug spanning-tree events output from one of my labs.  F0/3 is configured for portfast.  I shut/no shut it to see what happens.

*Mar  8 18:09:51.163: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to down
sw01#
*Mar  8 18:09:51.747: set portid: VLAN0007 Fa0/3: new port id 8003
*Mar  8 18:09:51.747: STP: VLAN0007 Fa0/3 ->jump to forwarding from blocking
sw01#
*Mar  8 18:09:53.739: %LINK-3-UPDOWN: Interface FastEthernet0/3, changed state to up
*Mar  8 18:09:54.739: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to up

Notice the “jump to forwarding from blocking”.

Here’s the same output when the port is not in portfast mode.  Notice the timestamps.  It takes about 30 seconds (2 x default foward delay) to go from blocking to listening to learning to forwarding.

*Mar  8 18:13:05.313: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to down
sw01#
*Mar  8 18:13:06.013: set portid: VLAN0007 Fa0/3: new port id 8003
*Mar  8 18:13:06.013: STP: VLAN0007 Fa0/3 -> listening
sw01#
*Mar  8 18:13:06.381: %LINK-3-UPDOWN: Interface FastEthernet0/3, changed state to up
*Mar  8 18:13:07.381: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/3, changed state to up
sw01#
*Mar  8 18:13:21.013: STP: VLAN0007 Fa0/3 -> learning
sw01#
*Mar  8 18:13:36.013: STP: VLAN0007 Fa0/3 -> forwarding

Send any obvious corrections and questions my way.

Aaron Conaway

I like to lean my head to the left, hit it with the palm of my right hand, and document what knowledge falls out.

Website - More Posts