Changing VLAN Root Bridge ID on a Layer 3 Switch

1.    First, you will need to identify the VLAN you wish to change. With Cisco switches (not sure about others yet), you can change the root bridge ID for each VLAN individually. Warning! This may/will cause a re-convergence on the network. My lab environment noticed very little issues, but again just a home lab and a medium/large network this can take down your network as everything tries to readjust. Again, all of my SOPs/tips have been done in a home lab, always follow proper procedures before performing changes on your live/home network.
2.    Make sure you design/choose your switch you wish to be root carefully. Usually, you want your big/fast switches to be the root so you don’t have your traffic handicapped at a small/slow switch. It is all depending on how you wish to design it.
3.    Once you identify your VLAN, perform the following to change the priority:
    a.    #configure terminal
        i.    #spanning-tree vlan XXX priority 4096
            1.    Numbers start from 0 and increment in the number 4096 intervals. So example: 0, 4096, 8192, 12288 etc.
        ii.    #exit
    b.    #write
4.    Sometimes this is quick, sometimes this can take a little time for the switches to readjust. Just a few simple commands, but can make a huge difference on the speed of your network.

Reference: https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2960/software/release/12-2_53_se/configuration/guide/2960scg/swstp.html

Configuring LACP EtherChannel on Cisco Switches

1.    First, identify which two interfaces on both devices you will be binding together. Our example we will do TenGigabit 5 and 6 on a Cisco 4500, and Ethernets 7 and 8 on a Nexus 5K.
2.    Once you identified your ports you wish to link together, then you can log into each of the switches you will be working on.
3.    Once you are logged in, first, shut down the interfaces you wish connect. This is Cisco best practice since EtherChannel can cause spanning tree loops if done incorrectly..
    a.    4500 Switch Commands
        i.    #conf t
        ii.    #int range tenGigabit 1/5-6
        iii.    #shut
    b.    Nexus 5K Commands
        i.    #conf t
        ii.    #int ethernet 1/7-8
        iii.    #shut
4.    Now that the interfaces are shut down, we can now continue with the configuration. First, we will do the Nexus 5K
    a.    #conf t (if not already there)
    b.    # int port-channel channel-number
    c.    #description TEST-EtherChannel
    d.    #exit
    e.    # int Ethernet 1/7-8
    f.    #switchport mode trunk
    g.    #(optional) switchport trunk allowed vlan vlan-number
    h.    #channel-group 11 mode active(it will attach to a port channel if already created and matching, if no port channel has been created previously, it will create one for you)
    i.    #exit
5.    Next, we will set up the same thing on the Catalyst 4500X. here, we will just jump straight to the interfaces and set up port-channel directly in the :
    a.    #conf t
    b.    #int range TenGigabit 1/5-6
    c.    #description test-EtherChannel
    d.    #switchport mode trunk
    e.    #channel-group 11 mode active
6.    Your Cisco switches now should be configured and ready to start linking. The last step is to turn on the interfaces. Remember, we shut them down first in order to protect the systems from spanning tree loops. This is especially true when you use the hard coding EtherChannel, but we shut them down anyways for Cisco best practice. Now go into each Cisco switch, select the interfaces in the EtherChannel again, and then turn on the interfaces. The following are the steps:
    a.    Cisco 4500X Example
        i.    #conf t
        ii.    #int range TenGig 1/5-6
        iii.    #no shut
    b.    Cisco Nexus 5K
        i.    #conf t
        ii.    #int Ethernet 1/7-8
        iii.    #no shut
7.    If you noticed, the Cisco Nexus you do not have to select a range for the interfaces. You can just select them. With the Catalayst, you must put in the range in order to select them.
8.    You should start seeing the connections come up. You can do the following to see the status:
    a.    Cisco Nexus 5K: #show interface status
    b.    Cisco Catalyst 4500X: #show ip interface status
   
References:

Cisco Nexus 5K
https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5500/sw/interfaces/6x/b_5500_Interfaces_Config_Guide_Release_6x/b_5500_Interfaces_Config_Guide_Release_602N12_chapter_011.html

Cisco Catalyst 4500X
https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst4500/12-2/3-1-1SG/configuration/guide/config/channel.pdf

Changing/Adding DHCP Relay Nexus 5K

1.    First, you want to verify the DHCP relays in the Nexus 5K with the following command:
    a.    #show ip DHCP relay
2.    Verify the relay address of the IP addresses.
3.    Escalate up to configuration terminal. Then select the interface/VLAN interface you wish to change the DHCP relay address for:
    a.    #conf t
    b.    #int vlan xxx
4.    Now you have the VLAN/interface selected. If the interface already has a DHCP relay, first, remove the old relay address with the no command:
    a.    #no ip dhcp relay address x.x.x.x
5.    Next, you can add the new DHCP relay address to the interface/VLAN:
    a.    #ip dhcp relay address x.x.x.x
6.    Finally, test your device to verify the systems on the network are receiving IPs.