CCNP Switching Exam Notes: Vlan Access Lists, Stp Topology, Virtual Router Redundancy Protocol (vrrp).

41.0 The steps involved in implementing VLAN access lists:
1. Define VLAN Access Map. To define a VLAN access-map use the command:

Switch(config)# vlan access-map <map-name) [sequence-number].
Access map statements are performed according to the sequence number.

2. Define matching conditions to identify traffic to be filtered. Use the access-map configuration command:

Switch(config-access-map)# match {ip address {acl-address {<acl-number> |<acl name>}} | {ipx address {<acl-number> | <acl name>}} | {mac address <acl-name>}
3. Define the action to be performed on the filtered traffic. Use the command:

Switch(config-access-map)# action {drop | forward [capture] | redirect <interface type> <mod>/<num>}

4. Apply the VACL to a VLAN interface. Use the global configuration command:

Switch(config)# vlan filter <map-name> vlan-list <list-of-vlans-here>

To configure Rapid Spanning Tree Protocol (RSTP) on an edge port, use the command
Switch(config-if)# spanning-tree portfast.
To enable Multiple Spanning Tree (MST) on a switch, use the command
Switch(config)# spanning-tree mode mst
To enter MST configuration mode on a switch, use the command
Switch(config)# spanning-tree mst configuration

42.0 The following are true about protected STP topology using Cisco switches:

1. When using "root guard" feature, a switch port blocks all superior BPDUs, or the ones with better bridge ID. No data can be sent or received through the port that is blocking any such BDPUs.
2. bpduguard is recommended to be enabled where PortFast is enabled. This is normally done on access layer switches, where the end user systems are connected.
3. True, a port configured with BPDU guard is put into errdisable state when a BPDU is received. 
4. BPDU guard is recommended on switch ports with PortFast already enabled.

UDLD monitors a port for bi-directional flow of data. This is done by sending Layer2 UDLD frames identifying the switch port at regular intervals. The far-end port echos the frames with its own identification added. If UDLD does not receive the echos, the port is either flagged or disabled depending on the configuration. All connected devices must support UDLD in order for the protocol to successfully identify the unidirectional links.

43.0 If you have enabled STP protection features, the following command lists the ports that have been labeled as having inconsistent state:
Show spanning-tree inconsistentports
The following command enables you to look at reasons for inconsistencies:
Show spanning-tree interface <type> <mod>/<num> [detail]

44.0 Catalyst switches typically use the following two types of files:
1. IOS image files: The switch binary software resides in the IOS image files. The IOS image files are internally stored in Flash memory of the switch.
2. Configuration files: These are the text files containing the configuration commands for operation of the switch.

The command:
copy running-config startup-config
-allows the running configuration file to be saved onto the startup configuration file on the switch. Make sure that you use this command whenever you have made any configuration changes to the switch. Otherwise, your configuration command are not permanently saved in the switch memory, and lost soon after power cycling the switch.
The command:
copy startup-config running-config
-allows startup configuration file to be copied into the current running configuration file. 
copy running-config tftp: 
-Copies the running configuration of a switch to a TFTP server. You will be prompted for the server address and destination filename.
copy tftp: startup-config
-This command is useful to restore the startup-config file incase the original is lost or corrupt. The command loads the startup-config file from a remote tftp server.

Frequently used show commands on a switch:
Show version: The command displays 
f. The current version of IOS running in a switch
g. Available hardware, RAM, Flash memory, 
h. Switch uptime
i. Configuration register's content
j. Reason for the last reload etc.

Show running-config [interface <type> <mod>/<num> | vlan <vlan-id> | module <mod>]: The command displays the contents of the configuration file.
Show tech-support: The command is primarily used to send switch information to Cisco TAC support personnel.
Verify flash:<filename> -This command is used to verify whether the Flash contents are intact, and not corrupted. The checksum of the flashfile specified is verified for correctness.

Given below are some of the important Gigabit Ethernet specifications:

he IOS image file name represents the IOS version along with other information. The image file has the format
xxxxx represents the Catalyst switch model. Here c4550 Corresponds to Catalyst 4550
yyyyy corresponds to the feature set available with the image.
Zz denotes the file format
Aaa-bbb.ccc represents IOS version.
aaa: represents the major release
bbb represents the maintenance release
ccc represents build level.
In the example given,
121-11c.EAI means version 12.1(12c)EAI.

45.0 The following are true about Virtual Router Redundancy protocol (VRRP):

1. VRRP will have one master router, and all other routers are in the backup state.
2. VRRP router priorities range from 1 to 254. By default, the priority is set to 100. 254 is the highest priority.
3. The MAC address of the virtual router is of the form 0000.5e00.01xx, where xx is the VRRP group number in the range 0 to 255 or 0 to ff hex.
4. The interval for VRRP advertisements is 1 second by default.
5. All VRRP routers are configured to preempt the current master router by default. The router priority should be highest for the preemption to occur.

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