Best Practice Recommendations for the Catalyst 6500 Series Switch

http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.2SX/best/practices/recommendations.html

Etherchannel Mode On and Spanning Tree Loop

A common issue during EtherChannel configuration is that the interfaces go into err-disable mode. This can be seen when Etherchannel is switched to the ON mode in one switch, and the other switch is not configured immediately. If left in this state for a minute or so, STP on the switch where EtherChannel is enabled thinks there is a loop. This causes the channeling ports to be put in err-disable state.


n order to resolve the issue, set the channel mode to desirable on both sides of the connection, and then re-enable the interfaces.


http://www.cisco.com/en/US/tech/tk389/tk213/technologies_configuration_example09186a0080094647.shtml

BPDU Guard

• Prevents a switch to be added to a port by mistake
• If any BPDU is received port will be put in err-disable
• Used with portfast ports
• Can't be used with root guard
• Blocks the whole port

Switch(config)# spanning-tree portfast bpduguard default

Switch(config-if)# spanning-tree bpdugard enable

MST Configuration

For MST to work between two switches the following has to be the same:

1. Name
2. Revision Number
3. Instance to VLAN Mapping

Switch(config)# spanning-tree mode mst

Switch(config)# spanning-tree mst configuration

Switch(config-mst)# name <instance-name>

Switch(config-mst)# revision <revision-number>

Switch(config-mst)# instance <instance-id> vlan <vlan-list>

Switch(config)# spanning-tree mst <instance-id> root [primary | secondary] diameter <diameter>

Switch(config)# spanning-tree mst <instance-id> priority <bridge-priority>

Switch(config-if)# spanning-tree mst <instance-id> cost <cost>

Switch(config-if)# spanning-tree mst <instance-id> port-priority <port-priority>

Switch(config)# spanning-tree mst <instance-id> mst hello-time <seconds>

Switch(config)# spanning-tree mst <instance-id> mst forward-time <seconds>

Switch(config)# spanning-tree mst <instance-id> mst max-age <seconds>

Difference between VTP versions

VTP version 1:

• Supports normal VLAN numbers (1-1001)
• Supports pruning of unused VLANs (no longer sends broadcasts and unknown unicasts
• supports cleartext and MD5 digest password

VTP version 2:

• Forwards the VTP messages without checking the version number or domain in transparent mode
• Supports Token Ring
• Performs consistency check on the VTP / VLAN parameters (from CLI or SNMP)
• Pass on Unrecognised TLVs

VTP version 3:

• Supports extended VLAN numbers (1-4095)
• Transfer information regarding Private VLAN structure
• Support for databases other than VLAN (for example MST)
• Protection from unintended database overrides during insertion of new switches
• Hidden password protection

- CCNP SWITCH 642-813 Official Certification Guide

- http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps708/solution_guide_c78_508010.html

Loop Guard

When BPDUs go missing, port is moved to loop inconsistent and kept in nondesignated role

• It only operates on interfaces that are considered point-to-point by the spanning tree.
• It can't be used with root guard
• It operates per VLAN
• It recovers automatically

Troubleshooting Mismatched Duplex

On the full-duplex side:

• High Rcv-Err
• Runts
• FCS-Err

On the half-duplex side:

• High Late-Col counter
• excessive collisions

CCNP-TSHOOT 642-832 - Official Certification Guide

Cisco Proprietary 802.1D Enhancements vs 802.1w

Cisco proprietary 802.1D enhancements (PortFast, UplinkFast and BackboneFast) are all implemented in 802.1w. Only PortFast requires manual configuration in 802.1w.

STP vs RSTP

802.1D: BPDUs originate from the root bridge and are relayed by all switches down the tree every Hello Time.
802.1w: BPDUs are sent out every switch port at Hello Time intervals, regardless of whether BPDUs are received from the root.

CCNP-SWITCH 642-813 Official Certification Guide