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Up to 9 Cisco Catalyst switches can be stacked together to build single logical StackWise switch since Cisco IOS XE Release 3.3.0SE. Prior to Cisco IOS XE Release3.3.0SE, up to 4 Cisco Catalyst switches could be stacked together.  
Reference: http://www.cisco.com/c/en/us/products/collateral/switches/catalyst-3850-series-switches/qa_c67-722110.html

Switch Stack Offline Configuration 
You can use the offline configuration feature to provision (to supply a configuration to) a new switch before it joins the switch stack. You can configure in advance the stack member number, the switch type, and the interfaces associated with a switch that is not currently part of the stack. The configuration that you create on the switch stack is called the provisioned configuration . The switch that is added to the switch stack and that receives this configuration is called the provisioned switch. 
You manually create the provisioned configuration through the switch stack-member-number provision type global configuration command. The provisioned configuration is automatically created when a switch is added to a switch stack and when no provisioned configuration exists. 
When you configure the interfaces associated with a provisioned switch (for example, as part of a VLAN), the switch stack accepts the configuration, and the information appears in the running configuration. The interface associated with the provisioned switch is not active, operates as if it is administratively shut down, and the no shutdown interface configuration command does not return it to active service. The interface associated with the provisioned switch does not appear in the display of the specific feature; for example, it does not appear in the show vlan user EXEC command output. 
The switch stack retains the provisioned configuration in the running configuration whether or not the provisioned switch is part of the stack. You can save the provisioned configuration to the startup configuration file by entering the copy running-config startup-config privileged EXEC command. The startup configuration file ensures that the switch stack can reload and can use the saved information whether or not the provisioned switch is part of the switch stack.  
Effects of Adding a Provisioned Switch to a Switch Stack 
When you add a provisioned switch to the switch stack, the stack applies either the provisioned configuration or the default configuration. Table 5-1 lists the events that occur when the switch stack compares the provisioned configuration with the provisioned switch. 

  

Reference: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750x_3560x/software/release/12-2_55_se/configuration/guide/3750xscg/swstack.html

The different etherchannel modes are described in the table below:

  

Both the auto and desirable PAgP modes allow interfaces to negotiate with partner interfaces to determine if they can form an EtherChannel based on criteria such as interface speed and, for Layer 2 EtherChannels, trunking state and VLAN numbers. 
Interfaces can form an EtherChannel when they are in different PAgP modes as long as the modes are compatible. For example:
An interface in the desirable mode can form an EtherChannel with another interface that is in the desirable or auto mode.  
An interface in the auto mode can form an EtherChannel with another interface in the desirable mode. 
An interface in the auto mode cannot form an EtherChannel with another interface that is also in the auto mode because neither interface starts PAgP negotiation.  
An interface in the on mode that is added to a port channel is forced to have the same characteristics as the already existing on mode interfaces in the channel. 
Reference: https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst4500/12-2/20ew/configuration/guide/config/channel.html

To start a new flow-based SPAN (FSPAN) session or flow-based RSPAN (FRSPAN) source or destination session, or to limit (filter) SPAN source traffic to specific VLANs, use the monitor session filter global configuration command. 
Usage Guidelines 
You can set a combined maximum of two local SPAN sessions and RSPAN source sessions. You can have a total of 66 SPAN and RSPAN sessions on a switch or switch stack. 
You can monitor traffic on a single VLAN or on a series or range of ports or VLANs. You select a series or range of VLANs by using the [ , | -] options. 
If you specify a series of VLANs, you must enter a space before and after the comma. If you specify a range of VLANs, you must enter a space before and after the hyphen ( -). 
VLAN filtering refers to analyzing network traffic on a selected set of VLANs on trunk source ports. By default, all VLANs are monitored on trunk source ports. You can use the monitor session session_number filter vlan vlan-id command to limit SPAN traffic on trunk source ports to only the specified VLANs. 
VLAN monitoring and VLAN filtering are mutually exclusive. If a VLAN is a source, VLAN filtering cannot be enabled. If VLAN filtering is configured, a VLAN cannot become a source. 
Reference: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3850/software/release/3se/network_management/command_reference/b_nm_3se_3850_cr/b_nm_3se_3850_cr_chapter_010.html#wp3875419997

You can analyze network traffic passing through ports or VLANs by using SPAN or RSPAN to send a copy of the traffic to another port on the switch or on another switch that has been connected to a network analyzer or other monitoring or security device. SPAN copies (or mirrors) traffic received or sent (or both) on source ports or source VLANs to a destination port for analysis. 
RSPAN supports source ports, source VLANs, and destination ports on different switches (or different switch stacks), enabling remote monitoring of multiple switches across your network. The traffic for each RSPAN session is carried over a user-specified RSPAN VLAN that is dedicated for that RSPAN session in all participating switches. The RSPAN traffic from the source ports or VLANs is copied into the RSPAN VLAN and forwarded over trunk ports carrying the RSPAN VLAN to a destination session monitoring the RSPAN VLAN. Each RSPAN source switch must have either ports or VLANs as RSPAN sources. The destination is always a physical port. 
Reference: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750x_3560x/software/release/12-2_55_se/configuration/guide/3750xscg/swspan.html

Here we have a situation where one switch is using active mode, which is an LACP mode, and the other is using desirable, which is a PAGP mode. You can not mix the LACP and PAGP protocols to form an etherchannel. Here is a summary of the various etherchannel modes:

  

Reference: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2960/software/release/12-2_55_se/configuration/guide/scg_2960/swethchl.html

The “monitor session filter” command is used to specify which VLANS are to be port mirrored using SPAN. This example shows how to monitor VLANs 1 through 5 and VLAN 9 when the SPAN source is a trunk interface: 
Switch(config)# monitor session 2 filter vlan 1 – 5 , 9 
Reference: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst4500/12-2/25ew/configuration/guide/conf/span.html/index.html#wp1066836

The Link Layer Discovery Protocol (LLDP) is a vendor-neutral link layer protocol in the Internet Protocol Suite used by network devices for advertising their identity, capabilities, and neighbors on an IEEE 802 local area network, principally wired Ethernet. LLDP performs functions similar to several proprietary protocols, such as the Cisco Discovery Protocol (CDP). 
Reference: http://en.wikipedia.org/wiki/Link_Layer_Discovery_Protocol

VTP allows switches to advertise VLAN information between other members of the same VTP domain. VTP allows a consistent view of the switched network across all switches. There are several reasons why the VLAN information can fail to be exchanged. 
Verify these items if switches that run VTP fail to exchange VLAN information:
VTP information only passes through a trunk port. Make sure that all ports that interconnect switches are configured as trunks and are actually trunking. 
Make sure that if EtherChannels are created between two switches, only Layer 2 EtherChannels propagate VLAN information. 
Make sure that the VLANs are active in all the devices. 
One of the switches must be the VTP server in a VTP domain. All VLAN changes must be done on this switch in order to have them propagated to the VTP clients. 
The VTP domain name must match and it is case sensitive. CISCO and cisco are two different domain names. 
Make sure that no password is set between the server and client. If any password is set, make sure that the password is the same on both sides. 
Reference: http://www.cisco.com/en/US/tech/tk389/tk689/technologies_tech_note09186a0080890613.shtml

  VTP version 1 and VTP version 2 do not propagate configuration information for extended-range VLANs (VLAN numbers 1006 to 4094). You must configure extended-range VLANs manually on each network device. 
  VTP version 3 supports extended-range VLANs (VLAN numbers 1006 to 4094). If you convert from VTP version 3 to VTP version 2, the VLANs in the range 1006 to 4094 are removed from VTP control. 
Reference: http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/15.1SY/config_guide/sup2T/vtp.pdf