Posts in 2013
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GRE Tunnel used as a OSPF Virtual-Link
Wednesday, May 01, 2013 in Cisco Networking
GRE - Generic Routing Encapsulation, is a method of tunneling data from one router to another. Packets of one routing protocol - PASSANGER PROTOCOL are being encapsulated into another routing protocol - TRANSPORT PROTOCOL. In this example there is a …
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OFPF Cost Tuning
Wednesday, May 01, 2013 in Cisco Networking
NLRI - Network Layer Reachability Information OSPF routes are mainly classified based on their metric, where the Metric and Cost are calculated based only on the Link Bandwidth. Cost = 100/(BW[Mbps]) There are two things you could play with here: 1. …
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OSPF Advanced Virtual Link configuration: Multiple Virtual-Link
Wednesday, May 01, 2013 in Cisco Networking
At this level I suppose you know how to configure the Virtual Link, and what is it’s purpose. Let’s get some deeper into clearing out some doubts. 1. What happens with the OSPF Neighbors, and how do I check the Virtual Link? Configure …
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OSPF Authentication
Wednesday, May 01, 2013 in Cisco Networking
OSPF supports two types of Authentication: 1. Plain Text (64-bit Password) ** (config-if)#ip ospf authentication-key ^&*(^*&&%** 2. MD5 (ID + 128-bit Password): ** (config-if)#ip ospf message-digest-key 1 MD5 ^&*^&^*** You can …
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EIGRP STUB
Sunday, April 28, 2013 in Cisco Networking
First a heads up - it’s a bit complicated because there are just too many details… Subjective impression! The command is rather straight forward: Cisqueros_1(config-router)#eigrp stub connected [connected | summary | static | …
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EIGRP Authentication and some EIGRP "tuning" options
Sunday, April 28, 2013 in Cisco Networking
EIGRP Authentication Like in OSPF - the configuration is done in the Interface Configuration mode. Unlike OSPF - EIGRP supports only MD5 authentication. Set the mode to MD5, even though it’s the default mode on most devices. This is an example …
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EIGRP Unequal Load Balancing - "variance" command
Sunday, April 28, 2013 in Cisco Networking
VARIANCE Command Variance is a EIGRP feature that enables UNEQUAL load balancing. The only condition that needs to be met is: Paths need to be in the routing table and MEAT THE FEASIBILITY CONDITION! (Routes ADVERTISED Distance must be lower then the …
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EIGRP: Route Summarization
Saturday, April 27, 2013 in Cisco Networking
The EIGRP route summarization is done exactly the same like RIP summarization, which makes sense because both protocols have the Distance Vector nature. It can also be done on ANY of the routers within the same EIGRP process, unlike the Link State …
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EIGRP: Timers, k-values, "neighbor" command
Saturday, April 27, 2013 in Cisco Networking
EIGRP Timers The EIGRP timers are configured (a bit non-intuitive commands from my point of view) on the interface towards the EIGRP neighbor: Set the Hello timer for the EIGRP 100 process: (config-if)#ip hello-interval eigrp 100 30 Set the Dead …
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RIP: Offset Lists and Update Control
Friday, April 26, 2013 in Cisco Networking
RIP offset list - used to INCREASE the Hop Count. To implement: - define the ACL defining the relevant routes - set the Hop Count to be increased (by 13 in this case): (config-router)#offset-list ACCESS_LIST out 13 Fa0/0 !!! Offset Lists work only …