As we knew, when we want to advertise a network in BGP we have to type the exact network and subnet mask of that network or it will not be placed into the BGP table. But with “auto-summary” command, we can advertise the classful network of our network if we have this classful or a subnet of this network in our routing table. Let’s have a small lab with the topology below:
We will use this topology in this lab:
Purpose of this lab
The purpose of this lab is to check which path R4 will choose to reach 10.1.1.0/24 (located on R1) as there are two paths:
+ The optimal path: R4 -> R2 -> R1
+ The other path: R4 -> R5 -> R3 -> R2 -> R1
In this article we will discuss about HSRP and do a lab on it.
Quick reminder about HSRP
+ Hot Standby Router Protocol (HSRP) is a Cisco proprietary protocol.
+ With HSRP, two or more devices support a virtual router with a fictitious MAC address and unique IP address
+ Hosts use this IP address as their default gateway and the MAC address for the Layer 2 header
+ The virtual router’s MAC address is 0000.0c07.ACxx , in which xx is the HSRP group. Multiple groups (virtual routers) are allowed.
+ The Active router forwards traffic. The Standby router is backup and monitors periodic hellos (multicast to 224.0.0.2,
UDP port 1985) to detect a failure of the active router.
+ The active router is chosen because it has the highest HSRP priority (default priority is 100). In case of a tie, the router
with the highest configured IP address wins the election
+ A new router with a higher priority does not cause an election unless it is configured to preempt.
HSRP States
+ Initial: HSRP is not running.
+ Learn: The router does not know the virtual IP address and is waiting to hear from the active router.
+ Listen: The router knows the IP and MAC of the virtual router, but it is not the active or standby router.
+ Speak: Router sends periodic HSRP hellos and participates in the election of the active router.
+ Standby: Router monitors hellos from active router and assumes responsibility if active router fails.
+ Active:Router forwards packets on behalf of the virtual router.
Load balancing traffic across two uplinks to two HSRP routers with a single HSRP group is not possible. The trick is to use two
HSRP groups:
+ One group assigns an active router to one switch.
+ The other group assigns another active router to the other switch.
(Reference: SWITCH official Certification Guide)
That is all for the boring HSRP theory, let do a lab to understand more about HSRP! We will use the topology below for this lab:
In this lab we will try to run a Frame Relay topology same as the one posted in TSHOOT demo ticket. The logical and physical topologies of this lab are shown below:
Logical topology:
Tasks in this lab:
+ Configure static mappings on R1 and R4.
+ Configure point-to-point subinterface on R2 & R3.
+ All routers must be able to ping themselves.
In the previous Frame Relay Point-to-Point Subinterface lab we have set up Layer 2 connection via Frame Relay but only adjacent routers can ping each other. For example R1 can ping R2 and R2 and ping R3 but R1 cannot ping R3. This is because R2 connects with R1 and R3 via point-to-point interfaces and they use separate subnets. In this lab we will use EIGRP to advertise these routes so that “remote” routers can ping each other.
IOS used in this lab: c3640-jk9s-mz.124-16.bin
Tasks for this lab:
+ Configure EIGRP so that R1, R2, R3 and R4 can see and ping each other
+ Configure default route on R1 to 209.65.200.226 of R6
+ Advertise that default route to other routers via EIGRP so that every router can go to the Internet
In this article we will discuss about the configuration on the switches of the TSHOOT Demo ticket. We post the topology here for your reference.
Layer2/3 topology
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