Route Summarization & Autosummarization?

DerekAustin26DerekAustin26 Posts: 275Member
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???
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Comments

  • dairou18dairou18 Posts: 34Member ■■□□□□□□□□
    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.
  • typeshtypesh Posts: 168Member
    See 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."
  • notgoing2failnotgoing2fail Posts: 1,138Member
    typesh wrote: »
    See 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...
  • DerekAustin26DerekAustin26 Posts: 275Member
    typesh wrote: »
    See 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?
  • typeshtypesh Posts: 168Member
    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.
  • DerekAustin26DerekAustin26 Posts: 275Member
    typesh wrote: »
    Autosummary is on by default for RIPv2 and EIGRP.

    And RIPv1
  • typeshtypesh Posts: 168Member
    And RIPv1

    Correct. However you cannot manually summarize with v1.
  • notgoing2failnotgoing2fail Posts: 1,138Member
    typesh wrote: »
    Correct. 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!!!
  • DerekAustin26DerekAustin26 Posts: 275Member
    typesh 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...
  • typeshtypesh Posts: 168Member
    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?
  • alan2308alan2308 Senior Member Ann Arbor, MIPosts: 1,854Member ■■■■■■■■□□
    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.
  • DerekAustin26DerekAustin26 Posts: 275Member
    It's 10.1.1.0 - Router 1 is 10.1.1.1 & Router 2 is 10.1.1.2
  • DerekAustin26DerekAustin26 Posts: 275Member
    alan2308 wrote: »
    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.

    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..
  • DerekAustin26DerekAustin26 Posts: 275Member
    typesh wrote: »
    What 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
  • typeshtypesh Posts: 168Member
    You 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.
  • DerekAustin26DerekAustin26 Posts: 275Member
    typesh wrote: »
    You 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?
  • typeshtypesh Posts: 168Member
    This is what you're looking for:
    alan2308 wrote: »
    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.
  • DerekAustin26DerekAustin26 Posts: 275Member
    typesh wrote: »
    This 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#
  • DerekAustin26DerekAustin26 Posts: 275Member
    typesh wrote: »
    This 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#
  • DerekAustin26DerekAustin26 Posts: 275Member
    typesh wrote: »
    This 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#
  • typeshtypesh Posts: 168Member
    Post your debug output.

    Did you try running clear ip route * on R2?
  • DerekAustin26DerekAustin26 Posts: 275Member
    did not clear ip route no..
  • DerekAustin26DerekAustin26 Posts: 275Member
    typesh wrote: »
    Post 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
  • DerekAustin26DerekAustin26 Posts: 275Member
    typesh wrote: »
    Post 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
  • alan2308alan2308 Senior Member Ann Arbor, MIPosts: 1,854Member ■■■■■■■■□□
    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.
  • typeshtypesh Posts: 168Member
    alan2308 wrote: »
    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.

    Oh I told him to put 172.16.1.0/24 between R1 and R2 so to avoid the contiguous set-up.
  • DerekAustin26DerekAustin26 Posts: 275Member
    alan2308 wrote: »
    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.

    I reloaded both. Still no cigar.. Same thing.
  • typeshtypesh Posts: 168Member
    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...
  • alan2308alan2308 Senior Member Ann Arbor, MIPosts: 1,854Member ■■■■■■■■□□
    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.
  • DerekAustin26DerekAustin26 Posts: 275Member
    alan2308 wrote: »
    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.

    Try changing your 3rd octets for your ethernet subnets to a 1 or 2 and see what happens
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