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Route Summarization & Autosummarization?
DerekAustin26
Member Posts: 275
in CCNA & CCENT
My Sources:
Per CCNA ICND2 Wendell ODOM,
Per CCNA Sybex Studyguide Todd Lammle
Per CCNA study guide by McGraw Hill
And some googling....
I cannot find the clear difference between Route Summarization & Autosummarization...
What is the difference???
Per CCNA ICND2 Wendell ODOM,
Per CCNA Sybex Studyguide Todd Lammle
Per CCNA study guide by McGraw Hill
And some googling....
I cannot find the clear difference between Route Summarization & Autosummarization...
What is the difference???
Comments
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Optionsdairou18 Member Posts: 34 ■■□□□□□□□□Autosummarization is when a routing protocol (EIGRP for example) automatically summarizes the address at the classful boundry. I believe Route summarization means you are going to manually summarize yourself and you dont necessarily have to summarize at the classful boundry.
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Optionstypesh Member Posts: 168See Page 218 - 221 in your ICND2 Book (and Page 215 "Route Summarization Strategies"). It's explained quite well in that section.
Autosummarization happens at the classfull boundary.
For example (on P. 219 of the Odom Book), Seville is connected to
10.3.4.0
10.3.5.0
10.3.6.0
10.3.7.0
When Seville advertises these routes to Albuquerque over their common 172.16.3.0 link, Seville advertises 10.0.0.0, meaning the entire 10.0.0.0 /8 range.
With manual summarization you can create a summary route that more closely fits the subnets that are actually connected to Seville. Seville does not have the entire 10.0.0.0 /8 network behind it- just the subnets mentioned above. With manual summarization you can choose the summary to be advertised instead of having the router summarize at the classfull boundary.
For example, the same subnets can be advertised as 10.3.4.0 255.255.252.0 which really means 10.3.4.0 - 10.3.7.255.
With Autosummary, Seville tells Albuquerque "I know of the entire 10.0.0.0 network." However when using manual summarization, Seville says "I know about 10.3.4.0 /22." -
Optionsnotgoing2fail Member Posts: 1,138See Page 218 - 221 in your ICND2 Book (and Page 215 "Route Summarization Strategies"). It's explained quite well in that section.
Autosummarization happens at the classfull boundary.
For example (on P. 219 of the Odom Book), Seville is connected to
10.3.4.0
10.3.5.0
10.3.6.0
10.3.7.0
When Seville advertises these routes to Albuquerque over their common 172.16.3.0 link, Seville advertises 10.0.0.0, meaning the entire 10.0.0.0 /8 range.
With manual summarization you can create a summary route that more closely fits the subnets that are actually connected to Seville. Seville does not have the entire 10.0.0.0 /8 network behind it- just the subnets mentioned above. With manual summarization you can choose the summary to be advertised instead of having the router summarize at the classfull boundary.
For example, the same subnets can be advertised as 10.3.4.0 255.255.252.0 which really means 10.3.4.0 - 10.3.7.255.
With Autosummary, Seville tells Albuquerque "I know of the entire 10.0.0.0 network." However when using manual summarization, Seville says "I know about 10.3.4.0 /22."
That's a pretty good job explaining the difference. Should clear up any confusion anyone has...
It's a pretty good question... -
OptionsDerekAustin26 Member Posts: 275See Page 218 - 221 in your ICND2 Book (and Page 215 "Route Summarization Strategies"). It's explained quite well in that section.
Autosummarization happens at the classfull boundary.
For example (on P. 219 of the Odom Book), Seville is connected to
10.3.4.0
10.3.5.0
10.3.6.0
10.3.7.0
When Seville advertises these routes to Albuquerque over their common 172.16.3.0 link, Seville advertises 10.0.0.0, meaning the entire 10.0.0.0 /8 range.
With manual summarization you can create a summary route that more closely fits the subnets that are actually connected to Seville. Seville does not have the entire 10.0.0.0 /8 network behind it- just the subnets mentioned above. With manual summarization you can choose the summary to be advertised instead of having the router summarize at the classfull boundary.
For example, the same subnets can be advertised as 10.3.4.0 255.255.252.0 which really means 10.3.4.0 - 10.3.7.255.
With Autosummary, Seville tells Albuquerque "I know of the entire 10.0.0.0 network." However when using manual summarization, Seville says "I know about 10.3.4.0 /22."
Very nicely explained! Now that chapter explains how to configure/enable Route Summarization but it doesnt show us how to configure/enable Autosummarization....
How do you configure Autosummarization? -
Optionstypesh Member Posts: 168DerekAustin26 wrote: »Very nicely explained! Now that chapter explains how to configure/enable Route Summarization but it doesnt show us how to configure/enable Autosummarization....
How do you configure Autosummarization?
For RIPv2: Cisco IOS IP Command*Reference, Volume 2*of 3: Routing Protocols, Release*12.2 - RIP Commands [Cisco IOS Software Releases 12.2 Mainline] - Cisco Systems
For EIGRP: Cisco IOS Release 12.0 Network Protocols Command Reference, Part 1 - EIGRP Commands - Cisco Systems
Autosummary is on by default for RIPv2 and EIGRP. -
Optionstypesh Member Posts: 168DerekAustin26 wrote: »And RIPv1
Correct. However you cannot manually summarize with v1. -
Optionsnotgoing2fail Member Posts: 1,138Correct. However you cannot manually summarize with v1.
Yeah, I hope people are aware enough to know that RIPv1 is nothing but classfull...so that in itself is autosummarization!!! -
OptionsDerekAustin26 Member Posts: 275For RIPv2: Cisco IOS IP Command*Reference, Volume 2*of 3: Routing Protocols, Release*12.2 - RIP Commands [Cisco IOS Software Releases 12.2 Mainline] - Cisco Systems
For EIGRP: Cisco IOS Release 12.0 Network Protocols Command Reference, Part 1 - EIGRP Commands - Cisco Systems
Autosummary is on by default for RIPv2 and EIGRP.
Okay so I tested this out on my virtual lab.
I setup 2 routers
On the 1st router I had 2 subnets. 10.2.1.0 & 10.2.2.0 (both with 255.255.255.0 as the mask)
I configured rip on both the routers and setup the serial line and everything.
When i was done, I went to Router 2 and entered "sho ip route"
instead of showing the default autosummarization of "10.2.0.0" via the s 0/0 port it learned the routes from.. It showed both routes learned from Router 1's IP address..
Now if autosummarization were on by default with RIPv1, why didnt it show just 10.2.0.0 instead? I dont understand... -
Optionstypesh Member Posts: 168DerekAustin26 wrote: »Okay so I tested this out on my virtual lab.
I setup 2 routers
On the 1st router I had 2 subnets. 10.2.1.0 & 10.2.2.0 (both with 255.255.255.0 as the mask)
I configured rip on both the routers and setup the serial line and everything.
When i was done, I went to Router 2 and entered "sho ip route"
instead of showing the default autosummarization of "10.2.0.0" via the s 0/0 port it learned the routes from.. It showed both routes learned from Router 1's IP address..
Now if autosummarization were on by default with RIPv1, why didnt it show just 10.2.0.0 instead? I dont understand...
What is the subnet of the link between the 2 Routers?
Is it 10.x.x.x /24? -
Optionsalan2308 Member Posts: 1,854 ■■■■■■■■□□DerekAustin26 wrote: »Okay so I tested this out on my virtual lab.
I setup 2 routers
On the 1st router I had 2 subnets. 10.2.1.0 & 10.2.2.0 (both with 255.255.255.0 as the mask)
I configured rip on both the routers and setup the serial line and everything.
When i was done, I went to Router 2 and entered "sho ip route"
instead of showing the default autosummarization of "10.2.0.0" via the s 0/0 port it learned the routes from.. It showed both routes learned from Router 1's IP address..
Now if autosummarization were on by default with RIPv1, why didnt it show just 10.2.0.0 instead? I dont understand...
Even though RIPv1 is a classful protocol, if you have any connected networks within the classful boundary (10.0.0.0/8 in this case), the router will assume that same subnet mask for all routes within that classful boundary. Does router 2 have anything directly connected to a network within 10.x.x.x?
And the summarization would be 10.0.0.0, not 10.2.0.0. The 10.x.x.x network is Class A. -
OptionsDerekAustin26 Member Posts: 275Even though RIPv1 is a classful protocol, if you have any connected networks within the classful boundary (10.0.0.0/8 in this case), the router will assume that same subnet mask for all routes within that classful boundary. Does router 2 have anything directly connected to a network within 10.x.x.x?
And the summarization would be 10.0.0.0, not 10.2.0.0. The 10.x.x.x network is Class A.
The network is simple.
Its router 1 with 2 subnets attached to it's fastethernet lan ports and then Router 2 is connected to it's Serial 0/0 port. Nothing else is attached to Router 2.
But still... According to the book, autosummarization is on by default for RIPv1. And I did not see any "autosummarization" going on.. -
OptionsDerekAustin26 Member Posts: 275What is the subnet of the link between the 2 Routers?
Is it 10.x.x.x /24?
It's 10.1.1.0 - Router 1 is 10.1.1.1 & Router 2 is 10.1.1.2
Mask is 255.255.255.0 -
Optionstypesh Member Posts: 168You wont see the Autosummarization because you have set it up as a Contiguous Network.
Since the link between R1 and R2 are of 10.x.x.x /24, R1 will advertise the individual subnets. R2 assumes that the subnets described in R1s updates use the same /24 mask since R2 has an interface in the same classfull (10.x.x.x) network.
Set the link between R1 and R2 to be 172.16.1.0/24.
Also turn on debug ip rip and have a look at the entries. -
OptionsDerekAustin26 Member Posts: 275You wont see the Autosummarization because you have set it up as a Contiguous Network.
Since the link between R1 and R2 are of 10.x.x.x /24, R1 will advertise the individual subnets. R2 assumes that the subnets described in R1s updates use the same /24 mask since R2 has an interface in the same classfull (10.x.x.x) network.
Set the link between R1 and R2 to be 172.16.1.0/24.
Also turn on debug ip rip and have a look at the entries.
okay well I did that. And when I do the "sho ip route" on R2 - it still shows the 2 routes as 10.2.1.0 & 10.2.2.0 from S0 of R1
It's not "Autosummarizing" them as 10.2.0.0 - Whats wrong? -
Optionstypesh Member Posts: 168This is what you're looking for:And the summarization would be 10.0.0.0, not 10.2.0.0. The 10.x.x.x network is Class A.
What is your output for debug ip rip on R2?
Post your config for R1 and R2. -
OptionsDerekAustin26 Member Posts: 275This is what you're looking for:
What is your output for debug ip rip on R2?
Post your config for R1 and R2.
ROUTER 1
Router>en
Router#sho ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O- OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default
U - per-user static route, o - ODR, P - periodic downloaded static route
T - traffic engineered route
Gateway of last resort is not set
172.16.0.0/24 is subnetted, 1 subnets
C 172.16.1.0 is directly connected, Serial0/0
10.0.0.0/24 is subnetted, 2 subnets
C 10.2.1.0 is directly connected, FastEthernet0/0
C 10.2.2.0 is directly connected, FastEthernet0/1
Router#
ROUTER 2
Router Con0 is now available
Press RETURN to get started!
Router>en
Router#sho ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O- OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default
U - per-user static route, o - ODR, P - periodic downloaded static route
T - traffic engineered route
Gateway of last resort is not set
172.16.0.0/24 is subnetted, 1 subnets
C 172.16.1.0 is directly connected, Serial0/0
10.0.0.0/24 is subnetted, 2 subnets
R 10.2.1.0 [120/1] via 172.16.1.1, 00:00:12, Serial0/0
R 10.2.2.0 [120/1] via 172.16.1.1, 00:00:12, Serial0/0
Router# -
OptionsDerekAustin26 Member Posts: 275This is what you're looking for:
What is your output for debug ip rip on R2?
Post your config for R1 and R2.
Router 1 Config
Router Con0 is now available
Press RETURN to get started!
Router>en
Router#sho run
Building configuration...
Current configuration : 625 bytes
!
version 12.2
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Router
!
!
!
ip subnet-zero
!
!
!
!
!
interface FastEthernet0/0
ip address 10.2.1.1 255.255.255.0
no ip directed-broadcast
!
interface Serial0/0
ip address 172.16.1.1 255.255.255.0
no ip directed-broadcast
clockrate 64000
!
interface FastEthernet0/1
ip address 10.2.2.1 255.255.255.0
no ip directed-broadcast
!
interface Serial0/1
no ip address
no ip directed-broadcast
shutdown
!
router rip
network 10.0.0.0
network 172.16.0.0
network 192.168.1.0
!
!
ip classless
no ip http server
!
!
!
line con 0
line aux 0
line vty 0 4
login
!
end
Router# -
OptionsDerekAustin26 Member Posts: 275This is what you're looking for:
What is your output for debug ip rip on R2?
Post your config for R1 and R2.
ROUTER 2 CONFIG
Router Con0 is now available
Press RETURN to get started!
Router>en
Router#sho run
Building configuration...
Current configuration : 625 bytes
!
version 12.2
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Router
!
!
!
ip subnet-zero
!
!
!
!
!
interface FastEthernet0/0
no ip address
no ip directed-broadcast
shutdown
!
interface Serial0/0
ip address 172.16.1.2 255.255.255.0
no ip directed-broadcast
!
interface FastEthernet0/1
no ip address
no ip directed-broadcast
shutdown
!
interface Serial0/1
no ip address
no ip directed-broadcast
shutdown
!
router rip
network 10.0.0.0
network 172.16.0.0
network 192.168.1.0
!
!
ip classless
no ip http server
!
!
!
line con 0
line aux 0
line vty 0 4
login
!
end
Router# -
Optionstypesh Member Posts: 168Post your debug output.
Did you try running clear ip route * on R2? -
OptionsDerekAustin26 Member Posts: 275Post your debug output.
Did you try running clear ip route * on R2?
Router 2 Debug
Router>en
Router#debug ip rip
RIP protocol debugging is on
Router#
*Jun 27 22:01:08.078: RIP: sending v1 update to 255.255.255.255 via Serial0/0 (172.16.1.2)
*Jun 27 22:01:08.078: RIP: build update entries
*Jun 27 22:01:08.078: subnet 10.2.1.0 metric 2
*Jun 27 22:01:08.078: subnet 10.2.2.0 metric 2 -
OptionsDerekAustin26 Member Posts: 275Post your debug output.
Did you try running clear ip route * on R2?
Router 1 Debug
Router Con0 is now available
Press RETURN to get started!
Router>en
Router#debug ip rip
RIP protocol debugging is on
Router#
*Jun 27 22:02:08.078: RIP: received v1 update from 172.16.1.2 on Serial0/0
*Jun 27 22:02:08.078: 10.2.1.0 in 2 hops
*Jun 27 22:02:08.078: 10.2.2.0 in 2 hops
*Jun 27 22:02:08.078: 172.16.1.0 in 1 hops
*Jun 27 22:02:09.906: RIP: sending v1 update to 255.255.255.255 via Serial0/0 (172.16.1.1)
*Jun 27 22:02:09.906: RIP: build update entries
*Jun 27 22:02:09.906: subnet 10.2.1.0 metric 1
*Jun 27 22:02:09.906: subnet 10.2.2.0 metric 1
*Jun 27 22:02:09.906: subnet 10.2.1.0 metric 1
*Jun 27 22:02:09.906: subnet 10.2.2.0 metric 1
*Jun 27 22:02:09.906: RIP: sending v1 update to 255.255.255.255 via FastEthernet0/0 (10.2.1.1)
*Jun 27 22:02:09.906: RIP: build update entries
*Jun 27 22:02:09.906: subnet 10.2.2.0 metric 1
*Jun 27 22:02:09.906: subnet 10.2.2.0 metric 1
*Jun 27 22:02:09.906: subnet 172.16.1.0 metric 1
*Jun 27 22:02:09.921: RIP: sending v1 update to 255.255.255.255 via FastEthernet0/1 (10.2.2.1)
*Jun 27 22:02:09.921: RIP: build update entries
*Jun 27 22:02:09.921: subnet 10.2.1.0 metric 1
*Jun 27 22:02:09.921: subnet 10.2.1.0 metric 1
*Jun 27 22:02:09.921: subnet 172.16.1.0 metric 1 -
Optionsalan2308 Member Posts: 1,854 ■■■■■■■■□□DerekAustin26 wrote: »It's 10.1.1.0 - Router 1 is 10.1.1.1 & Router 2 is 10.1.1.2
Mask is 255.255.255.0
But your configs and debug say the link is 172.16.1.0. Did you change them? Then you may need to restart the RIP processes. Reloading both routers will do the trick. Then you should see something more in tune with what you're expecting. -
Optionstypesh Member Posts: 168But your configs and debug say the link is 172.16.1.0. Did you change them? Then you may need to restart the RIP processes. Reloading both routers will do the trick. Then you should see something more in tune with what you're expecting.
Oh I told him to put 172.16.1.0/24 between R1 and R2 so to avoid the contiguous set-up. -
OptionsDerekAustin26 Member Posts: 275But your configs and debug say the link is 172.16.1.0. Did you change them? Then you may need to restart the RIP processes. Reloading both routers will do the trick. Then you should see something more in tune with what you're expecting.
I reloaded both. Still no cigar.. Same thing. -
Optionstypesh Member Posts: 168DerekAustin26 wrote: »Router 2 Debug
Router>en
Router#debug ip rip
RIP protocol debugging is on
Router#
*Jun 27 22:01:08.078: RIP: sending v1 update to 255.255.255.255 via Serial0/0 (172.16.1.2)
*Jun 27 22:01:08.078: RIP: build update entries
*Jun 27 22:01:08.078: subnet 10.2.1.0 metric 2
*Jun 27 22:01:08.078: subnet 10.2.2.0 metric 2
This is odd...
R2 is advertising these subnets back to R1, yet R2's doesn't appear to have turned off split-horizon... -
Optionsalan2308 Member Posts: 1,854 ■■■■■■■■□□Something just isn't right here. Here's what I just labbed up. RIPv1 with 10.0.0.0 and 192.168.1.0 in the process for R1:
R1:
eth0/0 10.1.0.1/24
eth0/1 10.2.0.1/24
s0/0/0 192.168.1.1/24
R2:
s0/0/0 192.168.1.2/24
on R2:
Router2#sh ip route
<snip>
R 10.0.0.0/8 [120/1] via 192.168.1.1, 00:00:08, Serial0/0/0
C 192.168.1.0/24 is directly connected, Serial0/0/0
Router2#debug ip rip
received v1 update from 192.168.1.1 on Serial0/0/0
10.0.0.0 in 1 hops
on R1:
Router1#debug ip rip
RIP: sending v1 update to 255.255.255.255 via Serial0/0/0 (192.168.1.1)
RIP: build update entries
network 10.0.0.0 metric 1
This is roughly what you should be seeing. In cases like this, I usually just wipe the routers and start over again. -
OptionsDerekAustin26 Member Posts: 275Something just isn't right here. Here's what I just labbed up. RIPv1 with 10.0.0.0 and 192.168.1.0 in the process for R1:
R1:
eth0/0 10.1.0.1/24
eth0/1 10.2.0.1/24
s0/0/0 192.168.1.1/24
R2:
s0/0/0 192.168.1.2/24
on R2:
Router2#sh ip route
<snip>
R 10.0.0.0/8 [120/1] via 192.168.1.1, 00:00:08, Serial0/0/0
C 192.168.1.0/24 is directly connected, Serial0/0/0
Router2#debug ip rip
received v1 update from 192.168.1.1 on Serial0/0/0
10.0.0.0 in 1 hops
on R1:
Router1#debug ip rip
RIP: sending v1 update to 255.255.255.255 via Serial0/0/0 (192.168.1.1)
RIP: build update entries
network 10.0.0.0 metric 1
This is roughly what you should be seeing. In cases like this, I usually just wipe the routers and start over again.
Try changing your 3rd octets for your ethernet subnets to a 1 or 2 and see what happens