Cisco ACI – Nexus 9000 Initial Configuration

Below is the Brief overview of the initial configuration process, and a brief introduction to some of the features initially presented to us on the switch platform.

Here are a few summarized thoughts:

• Calling it a switch is actually kind of funny to me. All ports are routed and shutdown by default, and though you can obviously “no shut” them, and you can convert to a switchport, the switch is clearly built for all-L3 operations. There are no advanced L2 features like FabricPath or vPC, so it’s either all L3 or run spanning-tree again.
• Neither the NXAPI or the Bash shell appear to be a licensed feature, though you do have to enable the feature through a single command.
• From an NXOS perspective, there’s really nothing beyond the bash shell or the API that will catch any seasoned Nexus veteran off guard. This was a very familiar interface and experience, and it truly felt like another Nexus device (with no L2 features, of course)

Below is the 30 minute video introducing the Nexus 9508 switch and performing an initial configuration.

Realtime Chat between Cisco Routers

You might probably know that it's possible to send messages from one vty line to another on a single Cisco router.

R1#send ?
  *        All tty lines
  <0-17>   Send a message to a specific line
  aux      Auxiliary line
  console  Primary terminal line
  log      Logging destinations
  qdm      Send a message to QDM client
  vty      Virtual terminal
  xsm      Send a message to XSM client

R1#send 1
Enter message, end with CTRL/Z; abort with CTRL/C:
Hi
^Z
Send message? [confirm]

R1#

***
***
*** Message from tty0 to tty1:
***
Hi

There is a way to send automatically some custom-made udp packets from a Cisco router to a specific destination, in order to emulate the heartbeat mechanism of SixXS. Tcl seemed like a nice option, but as far as i know its implementation in Cisco IOS doesn't support extensions (Tcl doesn't have a builtin command for udp channels, so we must use an extension to enable it).

Asynchronous Serial Traffic Over User Datagram Protocol or UDPTN (UDP Telnet) is an IOS feature that provides the ability to encapsulate asynchronous data into UDP packets, and then unreliably transmit this data without needing to establish a connection with a receiving device. UDPTN is similar to Telnet in that both are used to transmit data, but UDPTN is unique in that it does not require that a connection be established with a receiving device.

Its usage is quite simple. You just have to enable udptn as an output transport under your vtys and then open a connection to the remote end.

R1#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
R1(config)#line vty 0 15
R1(config-line)#transport output ssh udptn
R1(config-line)#^Z
R1#

R2#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
R2(config)#line vty 0 15
R2(config-line)#transport output ssh udptn
R2(config-line)#^Z
R2#

You have various options regarding the role of each device, but usually one end is transmitting and the other end is receiving. If you need 2-way communication, then you need to enable both directions. You can use any port above 1024 or just the default 57.

R1#udptn 1.1.1.2 3740 /transmit /receive
Trying 1.1.1.2, 3740 ... Open

R2#udptn 1.1.1.1 3740 /transmit /receive
Trying 1.1.1.1, 3740 ... Open

It becomes more interesting if you send packets to a multicast/broadcast address, so everyone having an open connection there will see the data.

There are some annoying things, like that you can't see locally the entered chars, or that you get chars on top of the previous chars (you can use spaces in order to clear the line), but you can't expect the full thing.

R2#udptn 1.1.1.1 3740 /transmit /receive
Trying 1.1.1.1, 3740 ... Open
How are you doing today?     ! This was typed on R1

R1#udptn 1.1.1.2 3740 /transmit /receive
Trying 1.1.1.2, 3740 ... Open
Fine, thanks                 ! This was typed on R2

Voila! You just made it possible to have a chat with your friend at a remote Cisco router! If you want to stop the session, you can use Ctrl-Shift-6 + x and then enter the "disconnect" command.

There are 2 terminal options that can be configured under source vtys and can change the behavior of text output:

dispatch-timeout 10000 : This one makes the packets be transmitted every 10 secs
dispatch-character 13 : This one causes the current number of typed chars to be sent after you press Enter (ASCII 13). By default each char is sent immediately.

Note : Because of its ability to send raw UDP datagrams that might conflict with other protocols, UDPTN has an implicit access list that only allows UDPTN connections to UDP port 57 (default) or UDP ports greater than 1024.

If only now i could find a way to send such messages automatically, i would probably solve my initial issue. EEM doesn't provide a mechanism to feed chars into a remote session and the Tcl "typeahead/exec" solution makes the process get stuck (and i can't find a way to clear it). Any idea how to send Ctrl-Shift-6 + x?
 

Cisco Configuration Partitioning

The Configuration Partitioning feature provides modularization ("partitioning") of the running configuration state to provide granular access to the running configuration in Cisco IOS software.

This feature is enabled by default in Cisco IOS software images that include this feature.

The configuration state of a device is retrieved dynamically whenever a user issues the show running-config command. When the Configuration Partitioning feature is enabled, the system groups the configuration state of the device into parts (called "partitions") so that only the configuration state the user wishes to review is retrieved when generating a displayed list of commands in the running configuration. This feature improves performance for high-end systems with complex configurations because only a part of the running configuration state is processed when generating the running configuration command list, as opposed to the existing method of processing the entire system configuration state.

Default configuration partitions are provided by the introduction of this feature; other Cisco IOS software features may define their own command partitions in later releases.

This feature was introduced in software images for the Cisco 7600 series in Release 12.2(33)SRB.

Benefits of Partitioning the Running Configuration

The Configuration Partitioning feature is the latest in a series of Configuration Generation Performance Enhancement Features for Cisco IOS software. This feature improves the system's response time by providing a method for querying only the system component you wish to review when issuing the show running-config command.

When the Configuration Partitioning feature is enabled, the system groups the configuration state of the device into parts (called "partitions") for the purpose of generating the virtual running configuration file (the list of configuration commands). A new command, show running-config partition, allows you to display only the part of the running configuration that you want to examine, rather than having to display the entire running configuration at once, or displaying only lines that match a certain string.

The key benefit of this feature is that it increases system performance by allowing the system to run the NVGEN process for only the collection of system components (such as specific interfaces) that you need to display. This is in contrast to other existing extensions to the show running-config command, which only filter the generated list after all system components have been processed.

The selective processing of the system's configuration state for the purpose of generating a partial running configuration is called "configuration partitioning."

More granular access to configuration information offers important performance benefits for high-end routing platforms with very large configuration files, while also enhancing configuration management by allowing advanced configuration features to be implemented at a more granular level. Advanced configuration options include Cisco IOS software support for provisioning of customer services, Config Rollback, Config Locking, and configuration access control.

Example

show running-config partition ?

Issuing this command will show you the list of running configuration parts available for display on your system.

If the Configuration Partitioning feature is supported on your system and is enabled, you will see the string "config partition is TRUE" as the first line of help output.

If you receive an error message when entering the command syntax shown here, this feature is not supported on your system. See the command documentation for the show running-config command for existing extensions of that command in other releases that allow you to show only part of the running configuration.

Router# show running-config partition ?

 config partition is TRUE 

  access-list       All access-list configurations

  boot              All boot configurations

  class-map         All class-map configurations

common            All remaining unregistered configurations

global-cdp        All global cdp configurations

interface         All Interface specific Configurations

ip-as-path        All IP as-path configurations

ip-community      All IP community list configurations

ip-domain-list    All ip domain list configurations

ip-prefix-list    All ip prefix-list configurations

ip-static-routes  All IP static configurations

line              All line mode configurations

policy-map        All policy-map configurations

route-map         All route-map configurations

router            All routing configurations

snmp              All SNMP configurations

tacacs            All TACACS configurations

As an example, to have the system perform the NVGEN process on only the components associated with the access-list parts of the running configuration state, and display only the access-list related configurations, you would enter the show running-config partition access-list command:

Router# show running-config partition access-list

        Building configuration...

Current configuration : 127 bytes

!

Configuration of Partition access-list 

!

!

!

access-list 90 permit 0.0.0.0 1.2.3.5

access-list 100 permit 10 any any

!

end

Disabling the Configuration Partitioning Feature

Because this feature offers improved performance for existing commands, this feature is enabled by default for Cisco IOS software images that support this feature. However, you may want to disable this feature if you determine that it is not needed, as this feature does use a small amount of system resources (memory and CPU utilization). To disable configuration partitioning, perform the following task, which assumes you are starting in user EXEC mode.  

Router(config)# no parser config partition 

Disabling config partitioning 

Router(config)#