RIP summary-address.

Hi all,

Using the "ip summary-address rip <network> <subnet-mask>" the documentation states that only one summary per major network per interface is allowed. However I am able to do more than one, and they get advertised as well...

Got two interfaces:
172.16.23.1/30
172.16.24.1/30

I can then do:

ip summary-address rip 172.16.24.0 255.255.255.0
ip summary-address rip 172.16.23.0 255.255.255.0

And it works. I should only be able to summarize once, because of the same major net.

Any ideas?

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Comments

EdTheLad

kpjungle wrote: »

Any ideas?

Contact your local Cisco representative and off to buy them a beer for fixing an ios limitation.Better yet, just buy me a beer!

APA

try this

ip summary-address rip 172.16.23.0 255.255.254.0 - this covers .23 & .24

I believe you are specifying two seperate major /24 networks hence why it is advertising it..... You aren't by any chance confusing the term classful network with major network are you? Please explain what you think the router should be advertising.

Can you post you full config so we can see how and where you are applying the summary statements.

APA

EdTheLad wrote: »

Contact your local Cisco representative and off to buy them a beer for fixing an ios limitation.Better yet, just buy me a beer!

Beer for me as well?

BennyLava

I have noticed this as well, just another of the many mistakes in Cisco documentation. If you compare this article on RIP summary addresses:

IP Summary Address for RIPv2 - Cisco Systems

with the 12.4 config guide:

Cisco IOS IP Routing Protocols Configuration Guide, Release 12.4 - Configuring Routing Information Protocol [Cisco IOS Software Releases 12.4 Mainline] - Cisco Systems

it almost looks like they copy/pasted something 10 years old and expected the whole thing to still be accurate

kpjungle

APA wrote: »

try this

ip summary-address rip 172.16.23.0 255.255.254.0 - this covers .23 & .24

I believe you are specifying two seperate major /24 networks hence why it is advertising it..... You aren't by any chance confusing the term classful network with major network are you? Please explain what you think the router should be advertising.

Can you post you full config so we can see how and where you are applying the summary statements.

No, the major net is 172.16.0.0.

Heres a quote:

"The following example is illegal, because both addresses to be summarized have the same major net. Each route summarization on an interface must have a unique major net, whether or not the addresses have unique address masks. int E1

...

ip summary-address rip 10.1.0.0 255.255.0.0

ip summary-address rip 10.2.0.0 255.255.255.0"

Hope its okay to quote this, otherwise please moderate mr. moderator

IP Summary Address for RIPv2 - Cisco Systems

APA

kpjungle wrote: »

No, the major net is 172.16.0.0.

Heres a quote:

"The following example is illegal, because both addresses to be summarized have the same major net. Each route summarization on an interface must have a unique major net, whether or not the addresses have unique address masks. int E1

...

ip summary-address rip 10.1.0.0 255.255.0.0

ip summary-address rip 10.2.0.0 255.255.255.0"

Hope its okay to quote this, otherwise please moderate mr. moderator

IP Summary Address for RIPv2 - Cisco Systems

That's the classful net you are talking about.... 172.16.0.0/12

I didn't think summary statements worked on that basis , also RIPv2 supporting classless routing...

So hence why I identified the major net's as being /24's on this occasion because your /30's belong to the /24 summary statements.... Which is why I wanted you to try and summarize with 172.16.23.0/23 and 172.16.24.0/24 then see which one gets advertised as you have .24 covered in the /23 and also by the /24... this should meet the rule...

Don't get to play with RIP much at all... so I wouldn't mind finding out if this is definitely a typo in Cisco Docs or whether RIPv2 ignores the classful net's

EdTheLad

APA wrote: »

That's the classful net you are talking about.... 172.16.0.0/12

I didn't think summary statements worked on that basis , also RIPv2 supporting classless routing...

So hence why I identified the major net's as being /24's on this occasion because your /30's belong to the /24 summary statements.... Which is why I wanted you to try and summarize with 172.16.23.0/23 and 172.16.24.0/24 then see which one gets advertised as you have .24 covered in the /23 and also by the /24... this should meet the rule...

Don't get to play with RIP much at all... so I wouldn't mind finding out if this is definitely a typo in Cisco Docs or whether RIPv2 ignores the classful net's

You gotta get your terminology straight, the major net is the "major classful boundary".If you want to see if multiple summaries per interface with the same major is possible , lab it up, it will take about 2 mins to check.
I've found so many cisco doc errors its not funny, there are too many platforms and too many IOS releases for you to be able to rely on cisco docs 100%.

APA

EdTheLad wrote: »

You gotta get your terminology straight, the major net is the "major classful boundary".If you want to see if multiple summaries per interface with the same major is possible , lab it up, it will take about 2 mins to check.
I've found so many cisco doc errors its not funny, there are too many platforms and too many IOS releases for you to be able to rely on cisco docs 100%.

Ed, I understand the terminology....

My point was that using a classless routing protocol... should negate your need to worry bout classful boundaries right... unless using 'auto summarization'

So will the summary statement still abide by classful rules when it shouldn't or will it just advertise the network that you specify in the summary statement thinking this is the major network(thinking classless here)......

I agree on the cisco doc errors as well..... but as I said I don't use RIP much at all so I would like to identify if it is indeed another one of those 'delightful' Cisco doc errors.....

If I get some time amongst my BGP studies this weekend, I'll lab this up and come back with my findings..... I know I've used multiple summary statements with eigrp on a single interface... however never with RIP.

EdTheLad

The rule had nothing to do with classless or classful, the rules stated you can only summarize once per major network.You can only manual summarize ripv2, so this whole discussion has been based on a classless protocol.
When discussing major network numbers this does not indicate a reference to classful routing.A major network is a major network weather its classful or classless, hence why i said go get to grips with the terminology.

APA

Like I said... I'll lab it up..

I don't think I'm doing a good job explaining how 'I think RIPv2 is interpreting the summary statement' which contradicts the Cisco docs...... However as you've pointed out it's probably just the Cisco docs totally incorrect on this part....