Comments on: Route Summarization http://ciscotips.wordpress.com/2006/05/12/route-summarization/ Make life easy for Cisco Engineers Sat, 02 Jan 2010 05:56:13 +0000 http://wordpress.com/ hourly 1 By: JB http://ciscotips.wordpress.com/2006/05/12/route-summarization/#comment-3580 JB Thu, 08 Oct 2009 16:40:42 +0000 https://ciscotips.wordpress.com/2006/05/12/route-summarization/#comment-3580 Because the first 6 digits (including leading zeros) in the first octet are all the same for each network (8,9,10,11), the mask would be 11111100.00000000.00000000.00000000 or 252.0.0.0 Because the first 6 digits (including leading zeros) in the first octet are all the same for each network (8,9,10,11), the mask would be

11111100.00000000.00000000.00000000 or
252.0.0.0

]]> By: amit http://ciscotips.wordpress.com/2006/05/12/route-summarization/#comment-3564 amit Wed, 02 Sep 2009 05:40:50 +0000 https://ciscotips.wordpress.com/2006/05/12/route-summarization/#comment-3564 is root summarization and supernetting same???? if not then why???? is root summarization and supernetting same????

if not then why????

]]> By: Shyam kumar Pundir http://ciscotips.wordpress.com/2006/05/12/route-summarization/#comment-3390 Shyam kumar Pundir Thu, 25 Sep 2008 06:44:05 +0000 https://ciscotips.wordpress.com/2006/05/12/route-summarization/#comment-3390 What is route summerization and how is work on routing protocol. What is route summerization and how is work on routing protocol.

]]> By: faisal http://ciscotips.wordpress.com/2006/05/12/route-summarization/#comment-3361 faisal Tue, 08 Jul 2008 08:52:51 +0000 https://ciscotips.wordpress.com/2006/05/12/route-summarization/#comment-3361 kindly favour me to understand the summerization of rputer IP kindly favour me to understand the summerization of rputer IP

]]> By: Mike Shafer http://ciscotips.wordpress.com/2006/05/12/route-summarization/#comment-3350 Mike Shafer Mon, 26 May 2008 19:50:13 +0000 https://ciscotips.wordpress.com/2006/05/12/route-summarization/#comment-3350 To continue on the above it appears that it's a RIP thing in not allowing summarization less than the classful boundary. I took my above configuration and changed it over to EIGRP and all worked just dandy! That is I was able to summarize the Class A addresses on the S1/0 interface using: p1R7(config-if)#ip summary-address eigrp 100 8.0.0.0 252.0.0.0 and the routes were summarized on the routing table on R21 as expected showing: D 8.0.0.0/6 [90/2323456] via 172.16.1.2, 00:00:15, Serial0 If anyone knows how to accomplish this using RIP v2 I would appreciate you're letting me know. I'm taking the BSCI exam in the near future and it's *my* $150 down the drain if I crash and burn! :) Cheers! MS To continue on the above it appears that it’s a RIP thing in not allowing summarization less than the classful boundary.

I took my above configuration and changed it over to EIGRP and all worked just dandy! That is I was able to summarize the Class A addresses on the S1/0 interface using:

p1R7(config-if)#ip summary-address eigrp 100 8.0.0.0 252.0.0.0

and the routes were summarized on the routing table on R21 as expected showing:

D 8.0.0.0/6 [90/2323456] via 172.16.1.2, 00:00:15, Serial0

If anyone knows how to accomplish this using RIP v2 I would appreciate you’re letting me know. I’m taking the BSCI exam in the near future and it’s *my* $150 down the drain if I crash and burn! :)

Cheers!

MS

]]> By: Mike Shafer http://ciscotips.wordpress.com/2006/05/12/route-summarization/#comment-3349 Mike Shafer Mon, 26 May 2008 18:39:55 +0000 https://ciscotips.wordpress.com/2006/05/12/route-summarization/#comment-3349 Small Correction: (this should not be on R4) If I redo this using p1R4(config-if)#ip summary-address rip 8.0.0.0 255.0.0.0 Should read: (but on R7) If I redo this using p1R7(config-if)#ip summary-address rip 8.0.0.0 255.0.0.0 Small Correction: (this should not be on R4)
If I redo this using
p1R4(config-if)#ip summary-address rip 8.0.0.0 255.0.0.0

Should read: (but on R7)
If I redo this using
p1R7(config-if)#ip summary-address rip 8.0.0.0 255.0.0.0

]]> By: Mike Shafer http://ciscotips.wordpress.com/2006/05/12/route-summarization/#comment-3348 Mike Shafer Mon, 26 May 2008 18:33:29 +0000 https://ciscotips.wordpress.com/2006/05/12/route-summarization/#comment-3348 Hi, Curious as to what I'm missing here as I set up a simulation of this in my lab. I have a router 7 (3640-ios 12.4) configured with 4 Ethernet interfaces with each connecting to a corresponding Ethernet interface on another router (routers 1-4) for five routers total. For simplicity all routers are running router rip no auto vers 2 net 192.168.0.0 net xxxx (as appropriate for the ip of lo0) and router R7 has the addition of net 172.16.0.0 to handle the serial connection to R21 On routers 1-4 I configured loopback0 as R1: 8.8.8.8/8 R2: 9.9.9.9/8 R3: 10.10.10.10/8 R4: 11.11.11.11/8 I then have S1/0 (IP 172.16.1.2/30) on R7 acting as the outbound connection to S0 (IP 172.16.1.1/30) on my primary router (R21) that connects to my LAN and is the gateway router to the firewall and Internet. I have the routers R1-R4 divided as various subnets of the address space 192.168.0.0/24. When I summarize this on the S1/0 interface as: #ip summary-address rip 192.168.0.0 255.255.255.0 it acts as expected and the routing table on R21 shows R 192.168.0.0/24 [120/1] via 172.16.1.2, 00:00:09, Serial0 and all the various subnetted interfaces can be successfully pinged from R21. However: If I also try to summarize the loopback interfaces on S1/0 I get: p1R4(config-if)#ip summary-address rip 8.0.0.0 252.0.0.0 Summary mask must be greater or equal to major net If I redo this using p1R4(config-if)#ip summary-address rip 8.0.0.0 255.0.0.0 the router is happy but of course this doesn't summarize the address space of 8.0.0.0/8-11.0.0.0/8 What am I missing/need to change to get this working? TIA! Cheers! Mike Shafer Hi,

Curious as to what I’m missing here as I set up a simulation of this in my lab. I have a router 7 (3640-ios 12.4) configured with 4 Ethernet interfaces with each connecting to a corresponding Ethernet interface on another router (routers 1-4) for five routers total.

For simplicity all routers are running
router rip
no auto
vers 2
net 192.168.0.0
net xxxx (as appropriate for the ip of lo0)

and router R7 has the addition of
net 172.16.0.0 to handle the serial connection to R21

On routers 1-4 I configured loopback0 as
R1: 8.8.8.8/8
R2: 9.9.9.9/8
R3: 10.10.10.10/8
R4: 11.11.11.11/8

I then have S1/0 (IP 172.16.1.2/30) on R7 acting as the outbound connection to S0 (IP 172.16.1.1/30) on my primary router (R21) that connects to my LAN and is the gateway router to the firewall and Internet.

I have the routers R1-R4 divided as various subnets of the address space 192.168.0.0/24. When I summarize this on the S1/0 interface as: #ip summary-address rip 192.168.0.0 255.255.255.0

it acts as expected and the routing table on R21 shows

R 192.168.0.0/24 [120/1] via 172.16.1.2, 00:00:09, Serial0

and all the various subnetted interfaces can be successfully pinged from R21.

However:
If I also try to summarize the loopback interfaces on S1/0 I get:
p1R4(config-if)#ip summary-address rip 8.0.0.0 252.0.0.0
Summary mask must be greater or equal to major net

If I redo this using
p1R4(config-if)#ip summary-address rip 8.0.0.0 255.0.0.0

the router is happy but of course this doesn’t summarize the address space of 8.0.0.0/8-11.0.0.0/8

What am I missing/need to change to get this working?

TIA!

Cheers!

Mike Shafer

]]> By: Jesse http://ciscotips.wordpress.com/2006/05/12/route-summarization/#comment-3309 Jesse Thu, 20 Mar 2008 21:41:34 +0000 https://ciscotips.wordpress.com/2006/05/12/route-summarization/#comment-3309 Josef, 252.0.0.0 is the correct mask. If you used 248.0.0.0, it would also include the networks 12.0.0.0/8, 13.0.0.0/8, 14.0.0.0/8, and 15.0.0.0/8. Josef,
252.0.0.0 is the correct mask. If you used 248.0.0.0, it would also include the networks 12.0.0.0/8, 13.0.0.0/8, 14.0.0.0/8, and 15.0.0.0/8.

]]> By: Joao Costa http://ciscotips.wordpress.com/2006/05/12/route-summarization/#comment-3283 Joao Costa Tue, 05 Feb 2008 01:26:46 +0000 https://ciscotips.wordpress.com/2006/05/12/route-summarization/#comment-3283 There is a tutorial on how to get summary routes at http://searchwarp.com/swa45047.htm There is a tutorial on how to get summary routes at http://searchwarp.com/swa45047.htm

]]> By: Josef http://ciscotips.wordpress.com/2006/05/12/route-summarization/#comment-3274 Josef Wed, 23 Jan 2008 16:20:31 +0000 https://ciscotips.wordpress.com/2006/05/12/route-summarization/#comment-3274 In the first paragraph, wouldn't the route mask be 248.0.0.0? In the first paragraph, wouldn’t the route mask be 248.0.0.0?

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