An introduction to Point-to-Point Protocol

The big picture PPP is a layer 2 WAN technology that is designed to establish connection between two nodes over a variety of network mediums. Features 1. It has built-in error detection. 2. Monitoring the quality of the link before sending frames. 3. Capability to encapsulate frames and carry them over various layer2 WAN technologies … Continue reading An introduction to Point-to-Point Protocol →

Frame relay: Multilink point to point frame relay

Reference: http://www.cisco.com/en/US/docs/ios/12_2s/feature/guide/fs_mfr.html Multilink Frame Relay (FRF.16.1) 1. This technology aggregates multiple number of physical serial interfaces into one bundle. a. This provides link redundancy i.e. if a physical link of a bundle has failed, the frame relay link will still be available. b. This also provides bandwidth aggregation from multiple serial interfaces. (See http://www.cisco.com/en/US/docs/ios/12_2s/feature/guide/fs_mfr.html#wp1054102) 2. The aggregated … Continue reading Frame relay: Multilink point to point frame relay →

Frame-relay: Inverse ARP

Frame relay is a packet switching technology that emulates like a switch. Switch uses ARP broadcast to find out the mac address of the host so that switch can forward the frame to the destined switch port. Frame relay however does not have broadcast ability, it uses encapsulation technique either Cisco or IETF encapsulation format. … Continue reading Frame-relay: Inverse ARP →

Spanning Tree Protocol (802.1D)

This protocol prevents bridging loop created by redundant links within switch network. STP calculation will make switch/es block its own port so that the switch path is one straight line and not a loop. This is perhaps the most confusing concept in switch, it is not extremely difficult but many terminologies and the method on … Continue reading Spanning Tree Protocol (802.1D) →

Catalyst Switch: No trunks is formed

I have connected two Cisco Catalyst 3560 switches together by a pair of fibre cables. No trunk was formed. The default interface configuration for Catalyst 3560 is dynamic auto, in Catalyst 3550 the default was dynamic desirable. Dynamic desirable is actively negotiating a trunk with another cisco catalyst switch, whereas dynamic auto is passively waiting … Continue reading Catalyst Switch: No trunks is formed →

Tshoot: A network was not shown in OSPFv3 routing table

Reference topology Refer to IPv6 Layer 3 topology. Reference explanation. While I was doing IPv6 redistribution from ripng to OSPFv3, I found that OSPFv3 routing table did not include the 2026::2:/122 network which is in the RIPng domain between DSW1 and R4. DSW1 however has all the RIPng external routes but cannot ping to 2026::1:/122 … Continue reading Tshoot: A network was not shown in OSPFv3 routing table →

EIGRP: Bandwidth Part2

R1#sh interfaces serial 0/0 Serial0/0 is up, line protocol is up Hardware is PowerQUICC Serial Description: This is a DCE to R2 Internet address is 10.0.1.1/24 MTU 1500 bytes, BW 1544 Kbit/sec, DLY 20000 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation HDLC, loopback not set Keepalive set (10 sec) Last input 00:00:06, output 00:00:05, … Continue reading EIGRP: Bandwidth Part2 →

EIGRP: Configuration and verification part1.1

*Mar 2 11:52:53.472: EIGRP: Received HELLO on Loopback1 nbr 10.1.1.1 *Mar 2 11:52:53.472: AS 100, Flags 0x0, Seq 0/0 idbQ 0/0 *Mar 2 11:52:53.472: EIGRP: Packet from ourselves ignored I made R1 advertise the route of the loopback1 interface, hello from loopback1 is ignored. R1#sh ip eigrp interfaces 100 IP-EIGRP interfaces for process 100 Xmit … Continue reading EIGRP: Configuration and verification part1.1 →

EIGRP: Configuration and verification Part1

Scenario: You are tasked to configure EIGRP routing among various departments. Loopback1 of R1 is Engineering, loopback2 of R2 is Marketing, loopback3 of R3 is Sales. All physical connections have already been installed as shown in this logical network diagram. You do not need to configure anything on the switch. The switch has a localized … Continue reading EIGRP: Configuration and verification Part1 →