EIGRP - cbtv3 VID 40 - 41 - 42 - 43 - lab base configuration Flashcards
Content : 1 ) Setting up EIGRP on all routes in same autonomous system 2) Auto summarisation and impact 3) Manual summary for more specific routes 4) Equal cost load balancing 5) Modify bandwidth and enable unequal cost load balancing 6) Modify hellos timers for speedy failover
after starting Eigrp command If we add the command - > network 172.16.1.0 How will this show up on the routing table and why ?
how do we make a specific host look like a host not summarized ?
this will enter the routes as classfull, even if we type host address it will auto summaries.
E.g > network 172.16.1.0 will be come 172.16.0.0 (auto summarized)
To over come this we have to use wild card subnet, similar to ospf (0.0.0.0)
Auto-summarisation is enabled by default.
Why auto summary on EIGRP ?
Answer:
If - 172.16.4.0/24 and all its specific routes cross over to a different network e.g 192.168.4.0/24 than
EIGRP will auto-summarise the route to 172.16.0.0/23.
This is to ease the routing update to other networks.
Why is there a null0 (zero) ?
If router “egg” has 3 network (10.1.0.1-3) connected to it and advertises it to the head office via a serial link.
The head office can send a packet for 10.1.0.1 and the network will receive it.
But if head office send a packet for 10.50.0.1 - what will happen ?
Egg router will normally send it to its default route, out into the internet. This is a security breach. Sharing internal packet out into the internet.
A: This is why EIGRP has put in the routing table a 10.0.0.0 to null0.
Meaning it the 10.50.0.1 does not match the specific route in the table it will bin that packet, this maintains security by not revealing internal route to the internet via the default route.
This backs up the rule of specificity that routes are prioritised if they are more specific.
How to stop auto summary ?
(How to configure no auto)
> router EIGRP 90
no auto-summary
Why do we want to turn off auto-summary ?
Specific routes advertised are better then having summary routes advertised.
It prevents loops
Give control to us the admin to control traffic flow
How to configure auto summary
In interface
> int s1/0
> ip summary-address EIGRP 90 10.0.0.0 255.255.252.0
This will only advertise these summary route down that specific interface only.
If we want it on other interface we have to do it on each interface
Advertising summary route is done on global or interface ?
Does it advertise globally or just on that interface ?
In interface
> int s1/0
> ip summary-address EIGRP 90 10.0.0.0 255.255.252.0
This will only advertise these summary route down that specific interface only.
If we want it on other interface we have to do it on each interface
How do we set up Equal cost load balancing on EiGRP ?
equal cost load balancing is on by default.
We have to make sure the Bandwidth and cost are the same. meaning everything is the same as the current route.
(( (NEED to Check) Sometime we might have to clear the Eigrp neighbor relation - (if possible just for that relationship. To re enter the new route.))
What is un-equal cost load balancing ?
Sharing packet to the same destination via two path which have different speed(Cost)
Why is Unequal cost load balancing need configuring ?
- equal cost load balancing is on by default.
Enabling unequal cost load balancing is needed because of the default setting. ((bandwidth is uneven) needs to be enabled)
How to clear EIGRP neighbour?
# > clear ip EIGRP neighbour > clear ip route would do the same also
Why Clear EiGRP neighbor ?
If we had 2 link EIGRP was load balancing on, EIGRP would only remember the bandwidth it started with. Meaning if we after change the bandwidth on one of the links we would have to re-form the EIGRP neighbour afresh for EIGRP to detect the new bandwidth
How to configure unequal cost load balancing
#> router EIGRP 90 > variance 2 > Variance ? it shows : metric variance multiplier
What is variance multiplier ?
and how is it used in the ‘un-equal cos load balancing’ ?
The best path cost 100!
So variance 2 means 100 x 2 = 200
meaning this is twice as slow as the best path
What this command does is :
It will enter a 2nd route that cost 200 into the routing table along with the primary.
So - you have 1 fast route and a 2nd route that is 2 times slower
If we put Variance 3 it will do the same but for 3 times slower the amount of the primary.
Show ip route : will show both routes to that destination on the same line
How to configure hello & dead timer at the same time?
> int s1/1 > ip hello-interval EIGRP-90 1(dead) cmd meaning > ip hellow-interval eigrp (Autonomus system number), ( Hello/dead timer)
How to check hello and dead timers?
Hello timer
> Show ip EIGRP interface details s1/1
How to configure Bandwidth and Delay on Eigrp ?
By default EIGRP uses bandwidth and delay. Which is k1 & k3.
These are changed under interface > int fa0/0 > bandwidth ..... > delay .....
