Currently browsing category

1 Layer 2 Technologies

MTU 101

MTU stands for Maximum Transmission Unit. This is the amount of data that can be transmitted by one protocol. MTU is used at every layer of the OSI stack, but it’s value is closely related to the layer/protocol. 1. On a router 1.1 Layer 2 – mtu On a router, …

PPP Authentication – EAP

1. One way authentication 1.1 EAP Server (Authenticator) PPP will require the use of a Radius. However, you can use the local usernames if you configure: Remember to configure the username and password that the client will use: 1.2 EAP Client (Authenticating) 2. Two way authentication On R1: On R2:

Routing over Frame Relay

1. Topologies 1.1 Full Mesh The simplest Frame Relay topology is the Full Mesh topology, where each router has a dedicated virtual circuit to another router. Unfortunately this design is rarely found in real life because each additional circuit costs. Of course, having so many circuits available makes it easy …

Bridging on a router

1. Bridging Transparent Bridging is the default operational mode of switches. They bridge between interfaces and switch between them without modifying any data in the frames. Routing is the default operation mode of routers. They route between interfaces, and when doing this they modify the packets (Source and Destination MAC, …

EtherChannel 101

An etherchannel is a logical port that consists of multiple links bundled into a single logical link. To have a working etherchannel you must use static config or a negotiation protocol (LACP or PAgP). All ports in an EtherChannel must operate at the same speed and duplex. When an EtherChannel …

VLANs

1. Supported VLANs Supported VLANs: 1-4094 Optional parameters: To verify: 1.1 Normal Range vs Extended Range Normal Range VLANs: 1-1005* – Supported by VTP v1,v2,v3 in all modes. Extended Range VLANs: 1006-4094 – Only supported in Transparent mode by VTPv1 and v2, and in all modes by VTP v3. * …

Private VLANs

Private VLANs partitions a regular VLAN domain into subdomains. Such a subdomain is created when a primary VLAN is paired with a secondary VLAN. Only a switch in VTP Transparent mode supports Private VLANs 1. Primary VLAN To set a VLAN as Primary VLAN, use: After the secondary VLANs are …

VTP 101

1. How it works VTP (VLAN Trunking Protocol) is used to advertise VLAN information between connected switches in a network. VTP messages are sent only on trunk ports. VTP advertises the VLAN_ID, VLAN_NAME, VLAN_TYPE and VLAN_STATE information for each VLAN. VTP doesn’t send any information regarding port assignment to VLANs. …

802.1s – MSTP

The number of STP or RSTP instances that can run on a switch is limited. It is usually enough for most implementations but if you need to run STP on more VLANs, then MSTP is the solution. MSTP maps multiple VLANs to the same STP instance. Even when PVST or …

802.1w – RSTP

Rapid Spanning Tree is an updated version of the original Spanning Tree protocol, standardized as 802.1w. It includes many of the Cisco proprietary features of PVST+. RSTP is backwards compatible with 802.1d STP but it has a few new features. To enable RSTP, use: 1. New features in RSTP 1.1 …