From: CCIE unnumbered (ccie.unnumbered@gmail.com)
Date: Mon Sep 22 2008 - 12:50:25 ART
Thank you for all the responses!
Huan Pham wrote:
> Hi Paul,
>
> You're correct about the behaviour of static route and network statement
> in EIGRP! I did not know that EIGRP (and RIP as you said) treated Static
> Routes that point to a connected interface similar as as Connected
> Interfaces! Very interesting behaviour! I labbed up a simple scenario
> and the behaviour is exactly as you said (although it is irrelevant to
> the example in Doc CD, as the static routes in the Doc CD use next hop
> IP address, instead of outgoing interfaces). However, I could not find
> this behaviour documented anywhere yet. Could you pls give me any
> pointer. Thanks.
>
> Thanks again for bringing this behaviour into my attention. This is what
> we benifit from taking part in discussion of the high quality mailing
> list such as GroupStudy.
>
>
> R2#sh ip int brief | ex unass
> Interface IP-Address OK? Method Status
> Protocol
> Serial1/1 23.0.0.2 YES manual up
> up
> R2#sh run
> router eigrp 100
> network 10.10.10.0 0.0.0.255
> network 23.0.0.2 0.0.0.0
> no auto-summary
>
> ip route 10.10.10.0 255.255.255.0 Null0
>
> R3#sh ip route eigrp
> 10.0.0.0/24 is subnetted, 1 subnets
> D 10.10.10.0 [90/2169856] via 23.0.0.2, 00:06:38, Serial1/3
>
>
>
>
>
>
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> paul cosgrove
> Sent: Sunday, 21 September 2008 10:20 PM
> To: Huan Pham
> Cc: Gary Duncanson; Cisco certification; ccie.unnumbered@gmail.com
> Subject: Re: Cisco DOCS confusion
>
> Hi Huan,
>
> You mentioned that 'network 0.0.0.0' with a static default route is a
> special case, but actually the same behaviour is seen for any static
> route pointing to a connected interface. Static routes pointing to
> connected interfaces are treated like connected interfaces themselves by
> EIGRP and RIP. If there is a matching network statement they will be
> advertised. The default route is not treated any differently.
>
> The example config from the cisco site is poorly explained, and has a
> few errors. Difficult to know if it was intended to show filtering, or
> an auto summarisation problem as Gary suggested. The text suggests to
> me that the number of lines in the acl, as well as the wildcard masks on
> the acl and network statement are all errors.
>
> The example shows a config for a router which has two interfaces in
> different major networks, 192.168.7.0 and 10.10.20.0. If auto
> summarisation is enabled on the router being configured (though off by
> default these days, it is not specifically disabled), then the
> 10.10.10.0 route will not be advertised to the 192.168.7.x neighbor,
> instead (without the distribute-list) it will receive 10.0.0.0/8.
>
> The distribute-list would stop this, so that only the two 192.168.x.x
> redistributed routes are advertised. If you wanted all three advertised
> you would have to disable auto summarisation.
>
> Paul.
>
> Huan Pham wrote:
>
>> HI Gary,
>>
>> I do not have that book in front of me. The no auto-summary command is
>>
> to disable automatic summmarization of routes advertized to neighbors
> at classfull boundary. This is not relevant to the wildcard mask
> specified after the network statement.
>
>> The IOS behaviour I see is that, if you do not specify the wildcard,
>>
> the router will convert it to the whole classfull network, and enables
> EIGRP on all interfaces that belong to that classfull network.
>
>> R1(config)#router ei 100
>> R1(config-router)#no auto-summary
>> R1(config-router)#net 150.1.1.0
>> R1(config-router)#
>>
>> R1#sh run | s router
>> router eigrp 100
>> network 150.1.0.0
>> no auto-summary
>>
>>
>>
>>
>> --- On Sun, 9/21/08, Gary Duncanson <garyduncanson@btinternet.com>
>>
> wrote:
>
>>
>>
>>> From: Gary Duncanson <garyduncanson@btinternet.com>
>>> Subject: Re: Cisco DOCS confusion
>>> To: "Huan Pham" <pnhuan@yahoo.com>
>>> Cc: "Cisco certification" <ccielab@groupstudy.com>,
>>> ccie.unnumbered@gmail.com
>>> Date: Sunday, September 21, 2008, 4:53 AM You can also disable
>>> automatic summarization in eigrp and get over the network wildcard
>>> mask hassles to some extent.
>>>
>>> no auto-summary
>>>
>>> Doyle Vol I pp315-316
>>>
>>> I have seen a number of variants in practice lab examples.
>>>
>>>
>>>
>>> ----- Original Message -----
>>> From: "Huan Pham" <pnhuan@yahoo.com>
>>> To: <ccielab@groupstudy.com>; "CCIE
>>> unnumbered" <ccie.unnumbered@gmail.com>
>>> Sent: Saturday, September 20, 2008 11:12 AM
>>> Subject: Re: Cisco DOCS confusion
>>>
>>>
>>>
>>>
>>>> This is a terrible example in the DOC CD. I cannot
>>>>
>>>>
>>> understand why it
>>>
>>>
>>>> exists in the DOC CD!!! It is just a terriblly wrong
>>>>
>>>>
>>> example, in my
>>>
>>>
>>>> opinion.
>>>>
>>>>
>>>>
>>>>> (1) I thought all three routes were advertised by "network" command
>>>>>
>
>
>>>>> under router eigrp 1
>>>>>
>>>>>
>>>> No, you are not correct. All three routes are
>>>>
>>>>
>>> advertized by the
>>>
>>>
>>>> redistribute static command.
>>>>
>>>> In the EIGRP, similar to all IGP, the network command
>>>>
>>>>
>>> is to specify what
>>>
>>>
>>>> interface(s) take part in the routing protocol. It is
>>>>
>>>>
>>> not to advertize the
>>>
>>>
>>>> subnets specify by that statement.
>>>>
>>>> EIGRP also requires you to put the wildcard mask. If
>>>>
>>>>
>>> you do not, then
>>>
>>>
>>>> EIGRP a classfull network is specified.
>>>>
>>>> In the example
>>>>
>>>> router eigrp 1
>>>> network 10.10.10.0
>>>>
>>>> is the same as
>>>>
>>>> router eigrp 1
>>>> network 10.0.0.0
>>>>
>>>> or
>>>>
>>>> router eigrp 1
>>>> network 10.0.0.0 0.255.255.255
>>>>
>>>> In EIGRP there's one special case where the
>>>>
>>>>
>>> network statement also
>>>
>>>
>>>> advertizes the route, is when you do network 0.0.0.0
>>>>
>>>>
>>> and you have a static
>>>
>>>
>>>> default route. In this case, the network 0.0.0.0
>>>>
>>>>
>>> statement also enables
>>>
>>>
>>>> EIGRP on all interfaces as well.
>>>>
>>>> router eigrp 1
>>>> network 0.0.0.0
>>>> ip route 0.0.0.0 0.0.0.0 null0
>>>>
>>>> In the DOC CD examle, these network statments for
>>>>
>>>>
>>> 192.168.0.0 and
>>>
>>>
>>>> 10.10.10.0 have nothing to do with the usage of
>>>>
>>>>
>>> distribute-list to control
>>>
>>>
>>>> redistribution from Static to EIGRP!
>>>>
>>>>
>>>>
>>>>> (2) the access-list 3 permit 192.168.x.0 should
>>>>>
>>>>>
>>> have
>>>
>>>
>>>>> wildcard mask 0.0.0.255?
>>>>>
>>>>>
>>>> You are right. Doc CD is wrong.
>>>>
>>>>
>>>>
>>>>> (3) I thought all three routes were redistributed
>>>>>
>>>>>
>>> by the
>>>
>>>
>>>>> *redistribute
>>>>> static* router configuration?
>>>>>
>>>>>
>>>> You are right. I do not know what they meant to
>>>>
>>>>
>>> blocked here ;) Maybe they
>>>
>>>
>>>> mean "deny 10.10.10.0 0.0.0.255" to block
>>>>
>>>>
>>> the last one (???!!!)
>>>
>>>
>>>>> (4) what does the *distribute-list 3 out static*
>>>>>
>>>>>
>>> command do
>>>
>>>
>>>>> in this case?
>>>>>
>>>>>
>>>> Nothing, unless they change the ACL 3 to block one of
>>>>
>>>>
>>> the three subnets.
>>>
>>>
>>>> In that case, the one blocked by the ACL will not be
>>>>
>>>>
>>> advertized into
>>>
>>>
>>>> EIGRP.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> --- On Sat, 9/20/08, CCIE unnumbered
>>>>
>>>>
>>> <ccie.unnumbered@gmail.com> wrote:
>>>
>>>
>>>>> From: CCIE unnumbered
>>>>>
>>>>>
>>> <ccie.unnumbered@gmail.com>
>>>
>>>
>>>>> Subject: Cisco DOCS confusion
>>>>> To: ccielab@groupstudy.com
>>>>> Date: Saturday, September 20, 2008, 3:20 PM Dear Groupstudy
>>>>> Experts:
>>>>>
>>>>> Please find a digest from
>>>>>
>>>>>
>>>>>
>>> http://www.cisco.com/en/US/docs/ios/iproute/configuration/guide/irp_i
>>> p_prot_indep_ps6350_TSD_Products_Configuration_Guide_Chapter.html#wp1
>>> 057083
>>>
>>>
>>>>> in the end of this message, and help me explain
>>>>>
>>>>>
>>> the
>>>
>>>
>>>>> description of the
>>>>> section. (1) I thought all three routes were
>>>>>
>>>>>
>>> advertised by
>>>
>>>
>>>>> "network"
>>>>> command under router eigrp 1
>>>>> (2) the access-list 3 permit 192.168.x.0 should
>>>>>
>>>>>
>>> have
>>>
>>>
>>>>> wildcard mask 0.0.0.255?
>>>>> (3) I thought all three routes were redistributed
>>>>>
>>>>>
>>> by the
>>>
>>>
>>>>> *redistribute
>>>>> static* router configuration?
>>>>> (4) what does the *distribute-list 3 out static*
>>>>>
>>>>>
>>> command do
>>>
>>>
>>>>> in this case?
>>>>>
>>>>> Static Routing Redistribution Example
>>>>>
>>>>> In the example that follows, three static routes
>>>>>
>>>>>
>>> are
>>>
>>>
>>>>> specified, two of which
>>>>> are to be advertised. The static routes are
>>>>>
>>>>>
>>> created by
>>>
>>>
>>>>> specifying the
>>>>> *redistribute
>>>>> static* router configuration command and then
>>>>>
>>>>>
>>> specifying an
>>>
>>>
>>>>> access list that
>>>>> allows only those two networks to be passed to the
>>>>>
>>>>>
>>> EIGRP
>>>
>>>
>>>>> process. Any
>>>>> redistributed static routes should be sourced by a
>>>>>
>>>>>
>>> single
>>>
>>>
>>>>> router to minimize
>>>>> the likelihood of creating a routing loop.
>>>>>
>>>>> Router(config)# *ip route 192.168.2.0
>>>>>
>>>>>
>>> 255.255.255.0
>>>
>>>
>>>>> 192.168.7.65
>>>>> *
>>>>>
>>>>> Router(config)# *ip route 192.168.5.0
>>>>>
>>>>>
>>> 255.255.255.0
>>>
>>>
>>>>> 192.168.7.65
>>>>> *
>>>>>
>>>>> Router(config)# *ip route 10.10.10.0
>>>>>
>>>>>
>>> 255.255.255.0
>>>
>>>
>>>>> 10.20.1.2
>>>>> *
>>>>>
>>>>> Router(config)# *!
>>>>> *
>>>>>
>>>>> Router(config)# *access-list 3 permit 192.168.2.0
>>>>> 0.0.255.255
>>>>> *
>>>>>
>>>>> Router(config)# *access-list 3 permit 192.168.5.0
>>>>> 0.0.255.255
>>>>> *
>>>>>
>>>>> Router(config)# *access-list 3 permit 10.10.10.0
>>>>>
>>>>>
>>> 0.0.0.255
>>>
>>>
>>>>> *
>>>>>
>>>>> Router(config)# *!
>>>>> *
>>>>>
>>>>> Router(config)# *router eigrp 1
>>>>> *
>>>>>
>>>>> Router(config-router)# *network 192.168.0.0
>>>>> *
>>>>>
>>>>> Router(config-router)# *network 10.10.10.0
>>>>> *
>>>>>
>>>>> Router(config-router)# *redistribute static
>>>>>
>>>>>
>>> metric 10000
>>>
>>>
>>>>> 100 255 1 1500
>>>>> *
>>>>>
>>>>> Router(config-router)# *distribute-list 3 out
>>>>>
>>>>>
>>> static
>>>
>>>
>>>>> *
>>>>>
>>>>>
>>>>> Thanks,
>>>>> --
>>>>> CCIE unnumbered
>>>>>
>>>>>
>>>>> Blogs and organic groups at http://www.ccie.net
>>>>>
>>>>>
>>>>>
>>>>>
>>> _____________________________________________________________________
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>>>
>>>
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>>>>>
>>>>>
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>>>>
>>>>
>>>>
>>>>
>>> _____________________________________________________________________
>>> __
>>>
>>>
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>>>>
>>>>
>> Blogs and organic groups at http://www.ccie.net
>>
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>
>
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