Month: May 2015

Router-to-Router VPN in a GRE Tunnel

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In this article I’m going to show you how you can create a VPN connection with RSA keys. We need to take several steps. Although there may be better solutions to create an encrypted tunnel, this one is widely supported on most routers.
For this scenario I use two 7200 series routers in GNS3 v1.VPN_GRE

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Using Stateful NAT with HSRP

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In this article, I add Statefull NAT to my previous MHSRP configuration. When I have 2 or more router in a subnet I can configure them for Hot Standby Router Configuration (HSRP) to achieve router redundancy or next hop redundancy.
If I add NAT to one of the routers, I will need to enable NAT on all the other routers as well. The problem is, when the active router fails, the other router takes over but it has no information about the translations on the previously active router. So there should be some way to synchronize the NAT translation table between the routers and this is what stateful NAT is about.

HSRP Read the rest of this entry »

Filtering LSAs and Routes in OSPF

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In this section I want to examine different filtering mechanisms in OSPF. I have a simple topology here and all areas have direct access to are 0.
Note that I perform most (but not all) of the filterings on ABRs.OSPF_FILTERING Read the rest of this entry »

Frame-Relay Traffic-Shaping (FRTS)

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So far, I have discussed some of QoS features. Here, I discuss FRTS.FRTS

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IP and IPv6 Conversions

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Since a lot of students have problem with converting binary, decimal and hexadecimal into each other, here is a four-part video to help you get the idea. Enjoy and share!
1: Converting binary to Decimal: http://www.youtube.com/watch?v=4ij5Ihp1Tfs
2: Converting Decimal to Binary: http://www.youtube.com/watch?v=SjQdNUmFoow
3: Hex to Decimal and Vice Versa: http://www.youtube.com/watch?v=LmLe_jRpZ1M
4: Hex to Binary and Vice Versa: http://www.youtube.com/watch?v=uQZVRzp5T-8

VRRP and GLBP

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In previous section I showed you how to configure HSRP on two or more routers. In this section I am going to show you how to configure VRRP and the newer Cisco proprietary protocol GLBP.

HSRP Read the rest of this entry »

Dynamic Multi-point VPN (DMVPN) Video Tutorial

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Here is a two-part video tutorial on DMVPN. I hope you enjoy it.
Don’t forget to subscribe (if you haven’t already) and also press the like button!

Weighted Random Early Detection (WRED)

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The topology is the same as before.WFQ

Old School

We have an old syntax and a new syntax for WRED. In old syntax we applied WRED to all queues in an interface. We could not distinguish between classes but we could read CoS values and configure different parameters for them. Here is a simple example: Read the rest of this entry »

HSRP and MHSRP on Cisco Routers

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In this article I am going to show you how Router Redundancy (First Hop Redundancy Protocols) can help us use multiple connections to other subnets or internet transparently.
You know that (without extra software) devices can be configured with only one default gateway and if that gateway fails for some reason, devices cannot reach to other subnets.

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QoS: Bandwidth command

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In previous article I used class-maps to classify flows and then I used marking (as close as possible to the source of the flow).
Now I want to apply some policing or shaping to my traffic on a link that is not fast enough to carry all our traffic. After all, we need QoS to control the usage of our limited resources (here, bandwidth).

WFQ Read the rest of this entry »