CCNP - ENTERPRISE - VLANs notes

- When configuring a Trunk link, be sure to configure the same native VLAN at the each end. If you leave a trunk with default settings, VLAN 1 will be used by default.
  If you see the cmd #switchport trunk natvie vlan [id] on one end and not on the other you will get a mismatch error
- On an ISL enabled trunk if it received an unencapsulated frame it will be dropped.

CCNP - ENTERPRISE - Implementing IP Switching notes

- GAP analysis should be conducted at the Plan phase of the Lifecycle Services approach
- NAT can consistantly increase the load on a CPU on a MLS switch.
- TTL decrementing and rewrite of Src and Dest MAC Addresses do not occur on a L2 switch
- L3 switching provides the ability to circumvent CPU processing

CCNP - ENTERPRISE - Preparing the Campus for Advanced Services notes

- With regards to Multicast, IGMP snooping is enabled by default on catalyst switches
- When traffic from a multicast source is received on a port that it not expected the router will drop the packets.
- 224.0.1.1 is reserved for Network Time Protocol
- You might implement Voice services on a network to reduce costs and increase productivity.

CCNP - ENTERPRISE - Port Security notes

- An attacker would launch an MAC Flood Attack to capture data from the network and to initiate a DoS attack.
- use the cmd #sh monitor session 1 detail to observe whether data is being sent in association with that session.

CCNP - ENTERPRISE - First Hop Redundancy notes

- A standby router configured with HSRP will take 9 seconds to detect the loss of an active router (based on default timers)
- With GLBP there is no limit to the number of routers you can implement in a group, however only a maximum of 4 active routers will be forwarding at any given time (due to a limit of 4 virtual MAC addresses that can be used with a group).
- Default GLBP priority is 100, when a router is the Active Virtual Gateway or an Active Virtual forwarder either the priority has been increased from the default on the AVG OR the Priority has been reduced from the default on the AVF

CCNP - ENTERPRISE - Inter-vlan Routing Notes

- Router interfaces on a Router-on-a-stick setup are configured as L3 subinterfaces

- Reasons you wouldn't need to implement an SVI;
i) Provide failover for a failed primary SVI
ii) Provide connectivity to an external router for inter-vlan routing

- The cmd 'Autostate Exclude' could be implemented on a port that is used for monitoring and is connected to an IDS

- A Glean adjacency is when a MLS connects directly to several hosts and the FIB table maintains a prefix for the subnet rather than individual host prefixes

- If you get 'incomplete' or 'drop' adjacencies check the switch hasn't been configured with unsupported software features.

CCNP - ENTERPRISE - Password recovery on a Catalyst switch

Part of the preparation work for my home lab is to clear off the old config on the recycled systems. This includes performing a password reset.

The steps on my catalyst switches are as follows:

1. Access ROMMON - power off the device, press the Mode button on the front, connect the power. When the 'x1' LED goes out release the Mode button and ROMMON will be presented in your terminal
2. Enable Flash - ROMMON: flash_int
3. Enter the Following cmd - :loader_helper
4. Check the directory structure - : dir flash:
5. Rename the Startup-config file - :rename flash:config.text flash:config.bak
6. Restart the system - :boot
7. At the prompt enter 'no', you do not wish to run through the automation steps
8. At this point you can either stop here and run the system as a fresh system or you can continue
9. Rename the config.old back to config.text - switch#rename flash:config.bak flash:config.text
10. Next, load the config file in the memory - switch#copy flash:config.text system:running-config
11. At this point you are now running your original config. All you need to do now is reset all your access passwords
12. Change the Enable Secret - switch(config)#enable secret [Secret]
13. Change the Enable Password - switch(config)#enable password [Password]
14. Change the Telnet password - switch(config)#line vty 0 4; switch(config-line)#password [Password] 
15. Set the VTY line to prompt for the password - switch(config-line)#login
16. Finally, save your running-config - switch#wr mem

CCNP - ENTERPRISE - How to access ROMMON

In your working environment how often do you really need to access ROMMON? if everything is in order and you have up to date documentation then I suspect not very often.

So, I come to preparing my new home lab for my CCNP SWITCH course and I've had to remove the old configuration off the recycled kit.

For my access server I'm going to run an old 2610 router, not the most feature rich router but it has a single ethernet interface which I run inter-VLAN routing off. I have 2 catalyst 3550's for my distribution layer and I have 2 Catalyst 2950's for the access layer.

Accessing ROMMON.
Accessing ROMMON is actually very simple on the catalyst switches. Power off your device. Hold the mode button down on the front of the box, then connect the power lead.

Wait for the 'x1' interface indicator to go out and then release the mode button.

For the 2610 you power cycle the system and at the point the boot process is displayed on screen you hit ctrl+Break.

CCNP - ENTERPRISE - To 'Delete' or to 'Erase'?

When do you use the commands Delete or Erase?

Well it depends on what you are wanting to do.

If you want to remove a file, you use the delete cmd, for example:
R1#delete flash:config.old
or
SW1#delete vlan.dat

If you want to remove system information you use the erase cmd, for example:
R1#erase startup-config

If in doubt use the ? to inspect your options:
R1#?

CCNP - ENTERPRISE - Subnet Mask vs Wildcard Mask

Something I find I struggle with is when to use a subnet mask and when to use a wildcard mask. This article is to simply set out the instances when you will use one or the other (not the actual steps to apply them).

Subnet Mask:

• When applying an IP to an interface
• Routing protocol summary addresses
• BGP
• PIX security appliance ACL's
• ASA security appliance ACL's
• When creating DHCP pools on a Switch or Router

Wildcard Mask:

• EIGRP network statements
• OSPF network statements
• VPN concentrator network lists (when setting the local and remote allowed networks)
• Router ACL's

This list is not exhaustive and I will add to it as I come across new instances where you use either a Subnet mask or Wildcard mask.