Course sections

1
Lecture 1: Identify, implement and troubleshoot IPv4 addressing and subnetting
2
Lecture 2: Identify, implement and troubleshoot IPv6 addressing and subnetting
3
Lecture 1: Troubleshoot reverse path forwarding
4
Lecture 2: Implement and troubleshoot IPv4 protocol independent multicast
5
Lecture 3: Implement and troubleshoot multicast source discovery protocol
6
Lecture 4: Describe IPv6 multicast
7
Lecture 1: Implement and troubleshoot static routing
8
Lecture 2: Implement and troubleshoot default routing
9
Lecture 3: Compare routing protocol types
10
Lecture 4: Implement, optimize and troubleshoot administrative distance
11
Lecture 5: Implement and troubleshoot passive interface
12
Lecture 6: Implement and troubleshoot VRF lite
13
Lecture 7: Implement, optimize and troubleshoot filtering with any routing protocol
14
Lecture 8: Implement, optimize and troubleshoot redistribution between any routing protocol
15
Lecture 9: Implement, optimize and troubleshoot manual and auto summarization with any routing protocol
16
Lecture 10: Implement, optimize and troubleshoot policy-based routing
17
Lecture 11: Identify and troubleshoot sub-optimal routing
18
Lecture 12: Implement and troubleshoot bidirectional forwarding detection
19
Lecture 13: Implement and troubleshoot loop prevention mechanisms
20
Lecture 14: Implement and troubleshoot routing protocol authentication
21
Lecture 1: Implement and troubleshoot RIPv2
22
Lecture 2: Describe RIPv6 [RIPng]
23
Lecture 1: Describe packet types
24
Lecture 2: Implement and troubleshoot neighbor relationship
25
Lecture 3: Implement and troubleshoot loop free path selection
26
Lecture 4: Implement and troubleshoot operations
27
Lecture 5: Implement and troubleshoot EIGRP stub
28
Lecture 6: Implement and troubleshoot load-balancing
29
Lecture 7: Implement EIGRP [multi-address] named mode
30
Lecture 8: Implement, troubleshoot and optimize EIGRP convergence and scalability
31
Lecture 1: Describe OSPF packet types
32
Lecture 2: Describe neighbor relationship
33
Lecture 3: Implement and troubleshoot OSPFv3 address-family support
34
Lecture 4: Implement and troubleshoot network types, area types and router types
35
Lecture 5: Implement and troubleshoot path preference
36
Lecture 6: Implement and troubleshoot operations
37
Lecture 1: Describe, implement and troubleshoot peer relationships
38
Lecture 7: Implement, troubleshoot and optimize OSPF convergence and scalability
39
Lecture 2: Implement and troubleshoot IBGP and EBGP
40
Lecture 3: Explain attributes and best-path selection
41
Lecture 4: Implement, optimize and troubleshoot routing policies
42
Lecture 5: Implement and troubleshoot scalability
43
Lecture 6: Implement and troubleshoot multiprotocol BGP
44
Lecture 7: Implement and troubleshoot AS path manipulations
45
Lecture 8: Implement and troubleshoot other BGP features
46
Lecture 9: Describe BGP fast convergence features
47
Lecture 1: Describe basic IS-IS network
48
Lecture 3: Describe network types, levels and router types
49
Lecture 4: Describe IS-IS operations
50
Lecture 5: Describe optimization features
51
Key Takeaways: Layer 3 Technologies
52
Quiz: Layer 3 Technologies

Layer 2 Technologies, Lecture 1

Lecture 1: Implement and troubleshoot switch administration

Implement and troubleshoot switch administration

Managing MAC address table

By default, MAC address learning is enabled on all interfaces and VLANs and MAC address aging is set to 300 seconds on a Cisco switch. You can control MAC address learning on an interface or VLAN to manage the available MAC address table space. Before you disable MAC address learning, be sure that you are familiar with the overall environment which includes network topology and the router system configuration. Disabling MAC address learning on an interface or VLAN could cause flooding in the network. You can disable MAC address learning on a single VLAN ID from 1 to 4094 (for example, no mac address-table learning vlan 229) or a range of VLAN IDs, separated by a hyphen or comma (for example, no mac address-table learning vlan 1-100, 16).

 

You can display the MAC address table by using one or more of the privileged EXEC commands.

show mac address-table address – Displays MAC address table information for the specified MAC address.

show mac address-table aging-time – Displays the aging time in all VLANs or the specified VLAN

Further Reading

http://goo.gl/BS6kzc

Errdisable recovery

If the configuration shows a port as enabled, but software on the switch detects an error situation on the port, the software shuts down that port. In other words, the port is automatically disabled by the switch operating system software because of an error condition that is encountered on the port. When a port is error disabled, it is effectively shut down and no traffic is sent or received on that port. The port LED is set to the amber and if you issue the show interfaces command, the port status shows err-disabled. Here is an example of what an error-disabled port looks like from the command-line interface (CLI) of the switch:

Switch#show interfaces gigabitethernet 5/1 status

 

Port     Name              Status              Vlan     Duplex  Speed Type

Gi4/1               err-disabled 100         full   1000 1000BaseSX

 

Or, if the interface has been disabled because of an error condition, you can see messages that are similar to these in both the console and the syslog:

%SPANTREE-SP-2-BLOCK_BPDUGUARD:

Received BPDU on port GigabitEthernet4/1 with BPDU Guard enabled. Disabling port.

 

%PM-SP-4-ERR_DISABLE:

bpduguard error detected on Gi4/1, putting Gi4/1 in err-disable state

In order to recover a port from the errdisable state, first identify and correct the underlying cause, and then re-enable the port. If you re-enable the port before you fix the actual problem, the ports could just become error disabled again. After you fix the root problem, the ports are still disabled if you have not configured errdisable recovery on the switch. In this case, you must re-enable the ports manually. Issue the shutdown command and then the no shutdown interface mode command on the associated interface in order to manually re-enable the ports.

 

Major reasons for errdisable are:

  • EthernetChannel misconfiguration
  • Duplex mismatch
  • BPDU port guard
  • UDLD
  • Link-flap error
  • Loopback error
  • Port security violation
  • L2tp guard
  • Incorrect SFP cable
  • 1X security violation

Further Reading

http://goo.gl/tKJuV8

L2 MTU

There are 3 types of MTU that can be configured on a switch:

  • Layer-2 MTU that affects 10 and 100 Mbps interfaces of a switch. Configured by system MTU {bytes} command in global config mode
  • Layer-2 MTU that affects 1000 Mbps and higher speed interfaces of a switch. Configured by system MTU jumbo {bytes} command in global configuration mode
  • Layer-3 MTU that affects SVIs and routed interfaces of a switch with IP addresses on them and originating or transit IP traffic that uses these interfaces as GW for routing between networks. Configured by system mtu routing {bytes} command in global config mode