====== Cisco Trunks ====== Nov 2017 \\ \\ THIS PAGE IS UNDER PROGRESS. THIS MESSGAE WILL DISAPPER UPON COMPLETION \\ \\ {{:topologyvlantrunk.jpg?650|}} \\ ---- ==== Introduction ==== In the previous topic regarding [[cisco_vlans_and_trunks_danscourses|Cisco VLANs and Trunks]] there are some videos outlining the theory of using VLANs and Trunks. Here we will look more at a worked example, and see some of the commands. \\ \\ //**Why is using a Trunk port important?**// There are a few reasons for this, but from my perspective it is down to a new product that we have, the T1. The T1 is effectively a group of blades in a box with two switches. Access to the switches, which have a number of ports, is limited to just a few ports on the front panel. This means we really need to be able to group all of our multicasts in to a single source interface, and connect this to the T1. \\ \\ {{ :mfelt1ciscotrunk.jpg?900 |}} \\ \\ Looking at the above diagram, we see an example of some sources on the left (could be encoders, receivers or streaming devices) feeding a cisco switch. The Cisco could have one or more VLANs configured, and we need to get all of these VLANs in to a single interface in our T1. If you only have a single VLAN, then a Trunk port is not required, but in some way it would be a good practice to use a trunk port, as if you needed to add VLANs later, half your work is already done. \\ \\ ---- ==== Example ==== \\ VLANs, while technically the same, can be broken down in to funciton. Some of these are: \\ Default VLAN Native VLAN Data VLAN Management VLAN Voice VLAN \\ I will discuss the meaning of these VLANs later, but for now I want to look at the configuration. ---- ==== Default VLAN ==== \\ As the name suggests, the default VLAN is the VLAN that the interfaces are initially located in. On a Cisco this is VLAN 1. From the Cisco CLI you can use the command show vlan to list the currently configured VLANs. \\ VLAN Name Status Ports ---- -------------------------------- --------- ------------------------------- 1 default active Fa0/1, Fa0/2, Fa0/3, Fa0/4 Fa0/5, Fa0/6, Fa0/7, Fa0/8 Fa0/9, Fa0/10, Fa0/11, Fa0/12 Fa0/13, Fa0/14, Fa0/15, Fa0/16 Fa0/17, Fa0/18, Fa0/19, Fa0/20 Fa0/21, Fa0/22, Fa0/23, Fa0/24 Gig0/1, Gig0/2 1002 fddi-default act/unsup 1003 token-ring-default act/unsup 1004 fddinet-default act/unsup 1005 trnet-default act/unsup Above we can see that VLAN 1 is listed as the default VLAN, this VLAN contains all the ports on the switch, this is how the switch will be configured from new when powered on. \\ \\ ---- ==== Native VLAN ==== \\ \\ \\ \\ ---- ==== notes ==== Default VLAN Native VLAN Data VLAN Management VLAN Voice VLAN Default VLAN is VLAN 1 VLAN Name Status Ports ---- -------------------------------- --------- ------------------------------- 1 default active Fa0/1, Fa0/2, Fa0/3, Fa0/4 Fa0/5, Fa0/6, Fa0/7, Fa0/8 Fa0/9, Fa0/10, Fa0/11, Fa0/12 Fa0/13, Fa0/14, Fa0/15, Fa0/16 Fa0/17, Fa0/18, Fa0/19, Fa0/20 Fa0/21, Fa0/22, Fa0/23, Fa0/24 Gig0/1, Gig0/2 1002 fddi-default act/unsup 1003 token-ring-default act/unsup 1004 fddinet-default act/unsup 1005 trnet-default act/unsup Cannot delete or rename vlan 1 vlan50 name student vlan99 name mgt exit sh vlan see vlan but no ports, need to assign ports. int fa 0/10 switchport mode access switchport access vlan 50 VLAN Name Status Ports ---- -------------------------------- --------- ------------------------------- 1 default active Fa0/1, Fa0/2, Fa0/3, Fa0/4 Fa0/5, Fa0/6, Fa0/7, Fa0/8 Fa0/9, Fa0/11, Fa0/12, Fa0/13 Fa0/14, Fa0/15, Fa0/16, Fa0/17 Fa0/18, Fa0/19, Fa0/20, Fa0/21 Fa0/22, Fa0/23, Fa0/24, Gig0/1 Gig0/2 50 student active Fa0/10 Switch(config-if)#ip address 192.168.99.2 255.255.255.0 Switch(config-if)#no shutdown not using vlan 1 is better for security, as guessing a vlan or interface number is harder. Native VLAN is important for Trunk Ports Interfaces (access ports) are one port per vlan effectivly (but no vlan configured) Trunk Port carries multiple VLANs across a single link (single interface) virtual terminal Switch(config)#line vty 0 15 Switch(config-line)#password cisco Switch(config-line)#login Switch(config)#enable secret cisco Switch(config-if)#switchport trunk encapsulation dot1q Switch(config-if)#switchport mode trunk Switch(config-if)# %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to down %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up Switch(config-if)#switchport trunk allowed vlan 1-99 interface FastEthernet0/1 switchport trunk allowed vlan 1-99 switchport trunk encapsulation dot1q switchport mode trunk port 1 no longer shown: VLAN Name Status Ports ---- -------------------------------- --------- ------------------------------- 1 default active Fa0/2, Fa0/3, Fa0/4, Fa0/5 Fa0/6, Fa0/7, Fa0/8, Fa0/9 Fa0/11, Fa0/12, Fa0/13, Fa0/14 Fa0/15, Fa0/16, Fa0/17, Fa0/18 Fa0/19, Fa0/20, Fa0/21, Fa0/22 Fa0/23, Fa0/24, Gig0/1, Gig0/2 50 student active Fa0/10 1002 fddi-default act/unsup 1003 token-ring-default act/unsup 1004 fddinet-default act/unsup 1005 trnet-default act/unsup Switch#sh interfaces trunk Port Mode Encapsulation Status Native vlan Fa0/1 on 802.1q trunking 1 Port Vlans allowed on trunk Fa0/1 1-99 Port Vlans allowed and active in management domain Fa0/1 1,50 Port Vlans in spanning tree forwarding state and not pruned Fa0/1 1,50 The native vlan defaults to vlan 1 (default vlan) Protocol 802.1q is the trunking protocol that puts tags on packets as they traverse the trunk (vlan tagging) If you have a device that does not support 802.1q, then the switch will put that traffic on the default vlan (if that vlan is allowed in the trunk) (the defaul vlan is vlan 1 unless you changed it) This traffic remains untagged. Switch(config)#vlan 80 Switch(config-vlan)#name native Switch#show interfaces fastEthernet 0/1 switchport Name: Fa0/1 Switchport: Enabled Administrative Mode: trunk Operational Mode: trunk Administrative Trunking Encapsulation: dot1q Operational Trunking Encapsulation: dot1q Negotiation of Trunking: On Access Mode VLAN: 1 (default) Trunking Native Mode VLAN: 1 (default) Voice VLAN: none Administrative private-vlan host-association: none Administrative private-vlan mapping: none Administrative private-vlan trunk native VLAN: none Administrative private-vlan trunk encapsulation: dot1q Administrative private-vlan trunk normal VLANs: none Administrative private-vlan trunk private VLANs: none Operational private-vlan: none Trunking VLANs Enabled: 1-99 Pruning VLANs Enabled: 2-1001 Capture Mode Disabled Capture VLANs Allowed: ALL Protected: false Unknown unicast blocked: disabled Unknown multicast blocked: disabled Appliance trust: none set native vlan Switch(config-if)#switchport trunk native vlan 80 show interfaces fastEthernet 0/1 switchport Name: Fa0/1 Switchport: Enabled Administrative Mode: trunk Operational Mode: trunk Administrative Trunking Encapsulation: dot1q Operational Trunking Encapsulation: dot1q Negotiation of Trunking: On Access Mode VLAN: 1 (default) Trunking Native Mode VLAN: 80 Voice VLAN: none Administrative private-vlan host-association: none Administrative private-vlan mapping: none Administrative private-vlan trunk native VLAN: none Administrative private-vlan trunk encapsulation: dot1q Administrative private-vlan trunk normal VLANs: none Administrative private-vlan trunk private VLANs: none Operational private-vlan: none Trunking VLANs Enabled: 1-99 Pruning VLANs Enabled: 2-1001 Capture Mode Disabled Capture VLANs Allowed: ALL Protected: false Unknown unicast blocked: disabled Unknown multicast blocked: disabled Appliance trust: none Switch#show interfaces trunk Port Mode Encapsulation Status Native vlan Fa0/1 on 802.1q trunking 80 Port Vlans allowed on trunk Fa0/1 1-99 Port Vlans allowed and active in management domain Fa0/1 1,50,80 Port Vlans in spanning tree forwarding state and not pruned Fa0/1 1,50,80 native vlan for backwards compatibility, or non tagged vlan traffic. REMEMBER TO DO THIS ON BOTH SWITCHES. You will see this message after configuring the first switch, on the second switch. %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/1 (1), with Switch FastEthernet0/1 (80). until you configure second switch. (CDP Cisco Discovery Protocol) This message occurs if Spanning Tree protocol is on. You will see an unblock message when second switch is configured. %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking FastEthernet0/1 on VLAN0001. Port consistency restored. do show ip interface br Switch(config)#do sh ip int br Interface IP-Address OK? Method Status Protocol FastEthernet0/1 unassigned YES unset up up FastEthernet0/2 unassigned YES unset down down FastEthernet0/3 unassigned YES unset down down FastEthernet0/4 unassigned YES unset down down FastEthernet0/5 unassigned YES unset up up FastEthernet0/6 unassigned YES unset down down FastEthernet0/7 unassigned YES unset down down FastEthernet0/8 unassigned YES unset down down FastEthernet0/9 unassigned YES unset down down FastEthernet0/10 unassigned YES unset up up FastEthernet0/11 unassigned YES unset down down FastEthernet0/12 unassigned YES unset down down FastEthernet0/13 unassigned YES unset down down FastEthernet0/14 unassigned YES unset down down FastEthernet0/15 unassigned YES unset down down FastEthernet0/16 unassigned YES unset down down FastEthernet0/17 unassigned YES unset down down FastEthernet0/18 unassigned YES unset down down FastEthernet0/19 unassigned YES unset down down FastEthernet0/20 unassigned YES unset down down FastEthernet0/21 unassigned YES unset down down FastEthernet0/22 unassigned YES unset down down FastEthernet0/23 unassigned YES unset down down FastEthernet0/24 unassigned YES unset up up GigabitEthernet0/1 unassigned YES unset down down GigabitEthernet0/2 unassigned YES unset down down Vlan1 unassigned YES unset administratively down down Vlan99 192.168.99.2 YES manual up up