Tag Archives: CCNA

Prefix-Lists Hacking.

ip prefix-list A permit ge 32 The above statement will match only hosts. ip prefix-list B permit ge 17 The above statement will match Any subnet in a class B address space. ip prefix-list C permit le 32 The above statement will match all routes. ip prefix-list D permit The above statement will match… Read More »

Day-34: Voice VLAN.

A voice VLAN is a VLAN ( virtual local area network) that is specifically allocated for the user’s voice data as we all know the VoIP traffic is very sensitive and VOIP traffic can deal with the delay, Bandwidth congestion, etc. The reason we need Voice VLAN is to prioritize that traffic after separating them. Once you will… Read More »

Day-33: Port Security.

Port security to filter traffic that is destined to or received from a specific host that is based on the host MAC address. Port Security feature remembers the Ethernet MAC address connected to the switch port and allows only that MAC address to communicate on that port. If any other MAC address tries to communicate through the port,… Read More »

Day-32: DTP(Dynamic Trunking Protocol).

DTP is a Cisco proprietary protocol that is automatically enabled on Catalyst 2960 and Catalyst 3560 Series switches. Switches from other vendors do not support DTP. DTP manages trunk negotiation only if the port on the neighbor switch is configured in a trunk mode that supports DTP. There are 2 dynamic modes available for the switchport mode command:… Read More »

Day-31: Native Vlans.

The major difference between a regular VLAN and the native VLAN is that frames from/to the native VLAN are carried untagged. The native VLAN is the one into which untagged traffic will be put when it’s received on a trunk port. This makes it possible for your VLAN to support legacy devices or devices that don’t tag their… Read More »

Day-30: ISL & 802.1Q Encapsulation.

ISL is a Cisco proprietary protocol and it Supports up to 1000 VLANs. ISL adds a 26-byte header and a 4-byte FCS (frame check sequence) is inserted. Hence a total of 30 Bytes of overhead so ISL is less preferred in networks because of its high overhead value which is added to each Ethernet frame. In ISL, the… Read More »

Day-29: VLAN Trunking.

The trunk port basically used to connect between switches. It carries traffic on one or more VLANs on the same physical links. Trunk ports are called tagged ports. Can have two or more VLANs configured. Can carry multiple VLAN information. By default, all the VLAN traffic is allowed from a trunk port. The trunk is basically carrying the… Read More »

Day-28: VLAN (Virtual local area networks)

VLANs define broadcast domains in a Layer 2 network. A broadcast domain is the set of all devices that will receive broadcast frames originating from any device within the set. Broadcast domains are typically bounded by routers because routers do not forward broadcast frames. Layer 2 switches create broadcast domains based on the configuration of the switch. Switches… Read More »

Day-27:LLDP(Link Layer Discovery Protocol )

LLDP is an Open standard protocol, equivalent to CDP Defined in IEEE 802.1ab Media Endpoint Discovery (MED) is an LLDP enhancement for Voice over IP (VoIP) applications. Limited to only 802.1 media types (i.e. Ethernet…but not WAN interfaces) CDP and LLDP can be operational on the same interface. LLDP uses attributes that contain type, length, and value descriptions(TLV… Read More »