Interesting, I guess that there is still a call out there to use RIP.
Otherwise, why would Cisco continue to make enhancements?
Good stuff to know.
Tony M.
#6172
----- Original Message -----
From: Chuck Larrieu
To:
Sent: Tuesday, July 24, 2001 8:08 PM
Subject: FW: IP Summary-address RIP [7:13699]
> I posted the following to the CCIE list and received no comment
whatsoever.
> apparently if a topic isn't directly related to any of the practice labs,
or
> is not perceived as being necessary to pass the Lab, no one is interested.
>
> since I know the folks on this list like to learn things, I thought I'd
post
> here
>
> -----Original Message-----
> From: Chuck Larrieu [mailto:[EMAIL PROTECTED]]
> Sent: Monday, July 23, 2001 10:10 PM
> To: CCIE_Lab Groupstudy List
> Subject: IP Summary-address RIP
>
>
> ran into this one while digging around CCO
>
> IP summary-address rip network mask
>
> this command is new to IOS 12.1
>
> it is an interface command, and ip split-horizon must be disabled for it
to
> work.
>
>
http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/ip_c
> /ipcprt2/1cdrip.htm#xtocid1773719
> watch the word wrap
>
> From CCO:
>
> Example 1: Correct Configuration
>
> The following example shows how the ip summary-address rip command works
> with autosummary addressing in RIP. In the example, the major network is
> 10.0.0.0. The summary address 10.2.0.0 overrides the autosummary address
of
> 10.0.0.0, so that 10.2.0.0 is advertised out interface e1 and 10.0.0.0 is
> not advertised.
> --------------------------------------------------------------------------
--
> ----
> Note If split horizon is enabled, neither autosummary nor interface
> summary addresses (those configured with the ip summary-address rip
command)
> are advertised.
> --------------------------------------------------------------------------
--
> ----
> router rip
> router int e1
> ip address 10.1.1.1 255.255.255.0
> (config-if)# ip summary-address rip 10.2.0.0 255.255.0.0
> no ip split-horizon
>
> router rip
> network 10.0.0.0
>
> [end of CCO quote]
>
> finally got this one to work. the doc CD omits the requirement that the
> sender must be a RIPv2 speaker. which makes sense, if you stop and think
> about it. sample configs below my signature.
>
> I got to wondering about the no ip split-horizon requirement on the
> interface where the summary takes place. if the RIP process receives the
> summarization information from an interface, then I guess it considers
> advertising that summary back out that address as a violation of split
> horizon. make sense? I can't think of any other reason for the
requirement.
>
> leads to some interesting possibilities. for example, suppose you have
some
> kind of RLAN private network, with lots of home user DSL lines aggregated
> into an ATM DS3 at the core. you want to conserve address space by
> allocating /29's to the home office users, but your RIP network requires a
> mask of /24.
>
> don't laugh, guys, I have a customer with exactly this situation :->
>
> you can advertise a /24 summary into your rip network. Cisco routers by
> default listen to RIPv2 advertisements, even if they are RIPv1 routers. So
> the RIPv2 advertisements will be accepted and placed into the routing
table.
> I don't know if this is true with other vendor's products.
>
> there are obviously some pitfalls. with split horizon disabled, one must
be
> aware of the implications. I have not yet tried various flavors of route
> maps or distribute lists to limit what goes out. also, one must take care
> that the RIPv1 routers are able to readvertise the summarized route.
> Assuming, as in the case I have mentioned, the RIPv1 router has only /24's
> on its attached interfaces, this should be OK. just something to be aware
> of.
>
> in terms of CCIE lab applicability, I suppose this can be one more tool in
> your arsenal. but only if your pod features 12.1 or better.
>
> Chuck
>
> interface Loopback0
> ip address 10.1.1.1 255.255.255.248
> !
> interface Loopback1
> ip address 10.1.1.9 255.255.255.248
> !
> interface Loopback2
> ip address 10.1.1.17 255.255.255.248
> !
> interface Loopback3
> ip address 10.1.1.25 255.255.255.248
> !
> interface Loopback4
> ip address 10.1.1.33 255.255.255.248
> !
> interface Ethernet0
> ip address 190.190.99.3 255.255.255.0
> no ip split-horizon
> ip summary-address rip 10.1.1.0 255.255.255.0
>
> interface Serial1
> ip address 190.190.23.3 255.255.255.0
> no ip split-horizon
> ip summary-address rip 10.1.0.0 255.255.0.0
> clockrate 2000000
> !
> router rip
> version 2
> passive-interface Loopback0
> passive-interface Loopback1
> passive-interface Loopback2
> passive-interface Loopback3
> passive-interface Loopback4
> network 10.0.0.0
> network 190.190.0.0
> no auto-summary
>
> another router:
>
> I 171.171.0.0/16 [100/9076] via 190.190.23.3, 00:01:10, Serial1
> S 100.0.0.0/8 is directly connected, Serial1
> 190.190.0.0/24 is subnetted, 2 subnets
> C 190.190.23.0 is directly connected, Serial1
> I 190.190.99.0 [100/8576] via 190.190.23.3, 00:01:10, Serial1
> 10.0.0.0/16 is subnetted, 1 subnets
> R 10.1.0.0 [120/1] via 190.190.23.3, 00:00:03, Serial1
>
> note the summarized route 10.1.0.0/16 ( from serial 1 above )
>
> another router:
>
> C 171.171.0.0/16 is directly connected, Loopback0
> 190.190.0.0/24 is subnetted, 2 subnets
> I 190.190.23.0 [100/8576] via 190.190.99.3, 00:01:09, Ethernet0
> C 190.190.99.0 is directly connected, Ethernet0
> 10.0.0.0/24 is subnetted, 1 subnets
> R 10.1.1.0 [120/1] via 190.190.99.3, 00:00:22, Ethernet0
>
> note the summarized route as a /24 ( from the ethernet interface above )
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=13705&t=13699
--------------------------------------------------
FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
