Cisco IOS Notes
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Cisco IOS Notes






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Cisco IOS Notes Cisco IOS Notes Document Transcript

  • 1 1. Changing password using IOS: Host(config)#enable password lever 1 <passwd> Host(config)#enable password level 15 <passwd> To remove password: no enable password 2. Setting IP address: Host(config)# interface vlan 1 Host(config-if)# ip address <ip> <subnet mask> Host(config-if)#ip default-gateway <ip> 3. Cisco Discovery Protocol: CDP Works if ports support SNAP, advertises every 60 sec. Multicast using address: 01:00:0c:cc:cc:cc ( default enable) Host(config-if)# cdp enable Host(config-if)#no cdp enable Host# show cdp interface [type modile/port] Host# show cdp neighbors [type moduel/port] [details] 4. Switch clustering To group up to 16 switches per cluster in order to have a single management switch. Host(config)# cluster enable <cluster name>
  • 2 5. VLAN and Trunking: Static VLAN Dynamic VLAN – Uses VMPS: Vlan Membership Policy Server Usually uses a one-to-one mapping between vlan and subnet (IP). Vlan can designed as:  end-to-end : Give flexibility and mobility. Each VLAN is made available at the access layer in every switch. Follows the 80/20 rule, 80% traffic is local, 20% traffic to cross the network core.  Local VLAN: going away from the 80/20 but using the reverse 20/80, i.e. 80% traffic is to cross the network core, and 20% local. More geographical or local selection. A trunk can transport more than one VLAN though a switch port. VLAN frame identification (tagging): Unique ID, user defined given to each frame on a trunk line. If frame are destined out an access link, the switch removes the tag. Two protocols: ISL and IEEE 802.1q ISL : Inter-switch Link Protocol : Cisco proprietary , adds a 26-byte header and a 4-byte trailer (CRC). The source VLAN has a 10bit VLAN ID (double tagging). IEEE 802.1Q: Adds a 4-byte tag (between source address and type/length fields of an Ethernet frame). The first two bytes are used as a Tag Protocol Identifier (TPID). The first two bytes also always have a value of 0x8100 to signify an 802.1Q tag. The remaining two bytes are used as a Tag Control Information (TCI) field. The TCI information contains a 3-bit priority field, which is used to implement class of service functions in the accompanying 802.1Q/802.1p prioritization standard. One bit of the TCI is a Canonical Format Indicator (CFI), flagging whether the MAC addresses are in canonical format. The last 12 bits are used as a VLAN Identifier (VID) to indicate the source VLAN for the frame. The VID can have values from 0 to 4095, but VLAN 0, 1, and 4095 are reserved. IEEE 802.1Q also introduces the concept of a native VLAN on a trunk. Frames belonging to this VLAN are not encapsulated with tagging information. In the event that an end station is connected to an 802.1Q trunk link, the end station will be able to receive and understand only the native VLAN frames. DTP: Dynamic Trunking Protocol: Cisco proprietary protocol to negotiate trunking mode between two switches (requires a Catalyst Supervisor unit).
  • 3 VTP: VLAN Trunking Protocol: help the management of the campus network. A VTP domain: The switches in a domain share VLAN information with each other in the domain. Switches in different domains do not share information. VTP distributes information about VLAN as well as actions to member switches. Three modes are available for each switch in the network: Server mode: Control VLAN creation and modification. Client mode: Passive and cannot create or modify VLANs. Transparent mode: Is on a stand-alone mode but relays the VTP advertisements (only inversion 2). Revision number: Important as it the number that establish the sequence and thus must be initialized and reset to 0 ( it is stored in NVRAM). There are three ways to do so: 1) clear config all 2) Set mode to transparent then server. 3) Change VTP domain name to bogus name, then change it back to the actual domain name. Configuration: Host(config)# interface interface module/port Host(config-if)# switchport mode trunk Host(config-if)# switchport trunk encapsulation {isl | dot1q} Host(config-if)# switchport trunk allowed vlan remove vlan-list Host(config-if)# switchport trunk allowed vlan add vlan-list Individually, these commands place the switch port into trunking mode, using the encapsulation specified as either isl or dot1q. The last two commands define which VLANs can be trunked over the link. A list of VLANs is first removed from the trunk because all VLANs (1–1005) are trunked by default. Then, a list of VLANs can be added back into the trunk. To view the trunking status on a switch port, use: show interface int mod/port switchport To configure a VTP Management Domain: Host# vlan database Host(vlan)# vtp domain <domain-name> Host(vlan)#vtp v2-mode Host(vlan)#vtp {server | client | transparent } Host(vlan)#vtp password <password>
  • 4 VTP Pruning: Switches forward traffic to all available ports in case the destination is unknown or forgotten (unknown unicast). Trunk ports are also included in that process, unless the command “ clear trunk “ is issued to remove those specific VLANs from the trunk. In general, trunk lines are managed by the VTP. If a switch is connected to another by a trunk but doesn’t have a port on a specific VLAN, then traffic destined to that VLAN should not be forwarded to that switch. This process is called pruning (similar to that described in class concerning the Spanning Tree Protocol, when the port was on a blocking mode). Remember only VLAN 2-1000 are eligible for pruning. To enable pruning, issue the command “ vtp pruning “ from the VLAN database. Summary commands: Create VLAN vlan database vlan vlan-num name vlan-name Assign port to VLAN interface interface module/number switchport mode access switchport access vlan vlan-num Display VLANs show vlan Configure trunk interface interface mod/port switchport mode trunk switchport trunk encapsulation {isl | dot1q} switchport trunk allowed vlan remove vlan-list switchport trunk allowed vlan add vlan-list Display trunks show interface mod/num switchport Configure VTP domain vlan database vtp domain domain-name Configure VTP mode vlan database vtp domain domain-name vtp {server | client | transparent} vtp password password Configure VTP version vlan database vtp v2-mode Display VTP status show vtp status show vtp counters VTP pruning vtp pruning