cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
376
Views
50
Helpful
22
Replies

summarization

alsayed
Beginner
Beginner

Hello Experts!

i Have 1 CORE 6507 SUP-720 and other 3 Sites in every site we have 6509-sup2.EIGRP Is a the Routing Protocole.i Need to perform summarization;this summarization should be done toward the core or from the core toward DSs

10xs

22 Replies 22

mohammedmahmoud
Advisor
Advisor

Hi,

To configure a summary aggregate address , use the "ip summary-address eigrp as-number network-address subnet-mask" command in interface configuration mode

interface ethernet 0

ip summary-address eigrp 109 192.168.0.0 255.255.0.0 --> Note that the subnet mask here is not written as wildcard

The router will advertise the summarized route only to its neighbor through this interface, while adding the summarized route to its null interface in its routing table and keeping the more specific route to be used when the neighbor routed packets arrived in order to be used.

NOTE: EIGRP summary routes are given an administrative distance value of 5 by default, can be changed in the summary command.

NOTE: The more specific route needs to be in the routing table for the summary route to be originated.

HTH, please rate all helpful posts,

Mohammed Mahmoud.

Hi mohammedmahmoud!

10xs for ur reply;the summarization FROM THE CORE TOWARD THE DSs Or From the DSs toward the Core

hi,

You should do the summarization from the DS towards the Core.

HTH, please do rate all helpful replies,

Mohammed Mahmoud.

HI mohammedmahmoud!

Kindly check attached file;so what this config does;sumarization from the CORE Toward the DSs

CORE!

Interface Portchannel200

descr connection to DS1

ip address 192.168.200.1 255.255.255.252

ip summary-address eigrp 1 10.250.0.0

!

Interface Portchannel100

descr connection to DS2

ip address 192.168.200.37 255.255.255.252

ip summary-address eigrp 1 10.250.0.0

!

Interface Portchannel1

descr connection to DS3

ip address 192.168.200.29 255.255.255.252

ip summary-address eigrp 1 10.200.0.0

!

***************************

CORE:Network:10.100.0.0 *

DS1: Network:10.200.0.0 *

DS2: Network:10.200.0.0 *

DS3: Network:10.250.0.0 *

***************************

this config work perfect but i didn't undesstand why the Summary from the CORE Towards the DSs.plz explain

Hi,

For the best practice you should do the summarization from the DS towards the Core, may be in your case there was a special issue to be considered, may be due to the direct link between DS1 and DS2.

HTH,

Mohammed Mahmoud.

Hi!

can u expain in wich cases we will sumarize from the CORE To the DSs

HI Ali

the config is missing subnet mask in the

ip summary-address eigrp 1 10.200.0.0 (subnet mask)

Thanks

Mahmood

also at the routing table i have seen a default route(s*) to to a null interface;from where came to the routing table/what its role does

10xs

Hi Ali,

When doing EIGRP summarization using this command, the router adds a summary route to null in its routing table automatically and advertise this route, but when the packet to be routed arrives at the router it is routed via the more specific route rather than this null route. (note that the route won't be summarized in the first place unless the more specific route was there).

HTH, please do rate helpful replies,

Mohammed Mahmoud.

Hi Mahmoud !

just 1 thing:can u expain in wich cases we will sumarize from the CORE To the DSs

10xs

Well if you can look at in a logical way. Your core router would have more routes, routes from external routers, you probably could have a ton of information there, but you would for your distribution switches which may have lesser processing power to have lesser overheads when trying to reach external routes. For reaching any of your external routes or destination a simple default route (summarizes everything) would be just enough on your distribution. Your core could do more specific routing once the packet is recieved there.

-Hoogen

Do rate if this helps :)

Hi,

As a best practice we do summarize from the distribution layer into the core via summary-address, summarization within the core is unnecessary. Because each distribution layer router is sending only summary information to the core, it is probably unnecessary to further summarize between core routers. However sometimes it is useful to summarize between core routers, or between the core and the distribution to minimize routing tables more, especially when the distribution routers are not that powerful.

HTH,

Mohammed Mahmoud.

Hi !

so i want to add another DS(DS4)the Network WOULD BE 10.150.0.0.noW from the Core Side wich summary should i send to the DS4 via the New L3 port-channel connected to the DS4 Based on my Attached DIAGRAMs

10XS

Ali,

Attachment is missing.

-amit singh

Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community:

Recognize Your Peers