From: Tshon (tshon@xxxxxxxxxxx)
Date: Fri Mar 01 2002 - 20:55:55 GMT-3
I believe that this will help you. The thing to get is that if you want
to have several distance commands set they are placed in opposite order
of what you would do with and access list.
Numerically, an administrative distance is an integer between 0 and 255.
In general, the higher the value, the lower the trust rating. An
administrative distance of 255 means the routing information source
cannot be trusted at all and should be ignored.
When the optional access list number is used with this command, it is
applied when a network is being inserted into the routing table. This
behavior allows filtering of networks according to the IP address of the
router supplying the routing information. This could be used, as an
example, to filter out possibly incorrect routing information from
routers not under your administrative control.
Always set the administrative distance from the least to the most
specific network.
Examples
In the following example, the router igrp global configuration command
sets up IGRP routing in autonomous system number 109. The network router
configuration commands specify IGRP routing on networks 192.31.7.0 and
128.88.0.0. The first distance router configuration command sets the
default administrative distance to 255, which instructs the Cisco IOS
software to ignore all routing updates from routers for which an
explicit distance has not been set. The second distance command sets the
administrative distance for all routers on the Class C network
192.31.7.0 to 90. The third distance command sets the administrative
distance for the router with the address 128.88.1.3 to 120.
router igrp 109
network 192.31.7.0
network 128.88.0.0
distance 255
distance 90 192.31.7.0 0.0.0.255
distance 120 128.88.1.3 0.0.0.0
-------------------------------------------------------------------------------
-
Note In this example, the distance command specifies an
administrative distance of 255 for networks 192. 31.7.0 and 128.88.0.0.
The second distance command specifies an administrative distance of 90
for network 192.31.7.0. The third distance command specifies an
administrative distance of 120 for network 128.88.0.0.
-------------------------------------------------------------------------------
-
In the following example, the set distance is from the least to the most
specific network.
router igrp 100
network 10.0.0.0
distance 22 10.0.0.0
distance 33 10.11.0.0 0.0.255.255
distance 44 10.11.12.0 0.0.0.255
-------------------------------------------------------------------------------
-
Note In this example, adding distance 255 to the end of the list
would override the distance values for all networks within the range
specified in the example. The result is that the distance values are set
to 255.
Tshon
ying chang wrote:
> Thanks to you and Bob, I think I understand how it works now. In my
> case, we could not do it, because they are executed in order thus the
> second statement will overwrite the first one. It sure is an
> interesting way to control routes though.
>
> Thanks,
> Chang
>
>> From: "Wade Edwards" <wade.edwards@powerupnetworks.com>
>> Reply-To: "Wade Edwards" <wade.edwards@powerupnetworks.com>
>> To: "ying chang" <ying_c@hotmail.com>
>> CC: <ccielab@groupstudy.com>
>> Subject: RE: Manipulate administrative distance
>> Date: Fri, 1 Mar 2002 14:58:20 -0600
>>
>> This is an interesting dilemma. The problem is that you can only have
>> one distance statement that has a particular network address and
>> wildcard mask. So this is what I purpose, I don't know if this will
>> work but, do two distance statements one pointing directly to the
>> neighbor address and the other pointing to the subnet where the neighbor
>> is coming from. On one distance statement place an access-list allowing
>> only one set of routes. On the other statement place another
>> access-list allowing only the other set of routes. I don't know if this
>> will work because one might take precedence over the other but it is
>> worth a try.
>>
>> L8r.
>>
>> -----Original Message-----
>> From: ying chang [mailto:ying_c@hotmail.com]
>> Sent: Friday, March 01, 2002 1:57 PM
>> To: Wade Edwards
>> Cc: ccielab@groupstudy.com
>> Subject: RE: Manipulate administrative distance
>>
>> Hopefully I can learn how to use it correctly. The CDROM
>> http://127.0.0.1:8080/cc/td/doc/product/software/ios121/121cgcr/ip_r/ipr
>> prt2/1rdindep.htm#xtocid172612
>> has a few examples, but I could not make them work for me.
>>
>> Let's get back to my original question, R3 passes 192.168.1.0/24 and
>> 172.160.0.0/16 to R2, how can I change their AD to 192 and 172
>> respectively?
>> As you can see from the sample output, it does work on 150.100.1.0/24
>> and
>> 150.100.2.0/24 which was passed from R1 and was changed to 130. Am I
>> missing
>> something here?
>>
>> By the way, please ignore my comment on subnet 172. Doyle I chap 13 has
>> some
>> examples with acl.
>>
>> Below is the output from debug ip igrp tran:
>>
>> r2#debug ip igrp trans
>> IGRP protocol debugging is on
>> r2#
>> 06:51:25: IGRP: received update from 150.100.11.1 on Serial1
>> 06:51:25: subnet 150.100.50.0, metric 160350 (neighbor 158350)
>> 06:51:25: subnet 150.100.2.0, metric 160350 (neighbor 158350)
>> 06:51:25: subnet 150.100.1.0, metric 10576 (neighbor 8576)
>> 06:51:25: subnet 150.100.10.0, metric 8576 (neighbor 1100)
>> 06:51:25: IGRP: received update from 160.100.77.125 on Ethernet0
>> 06:51:25: network 172.160.0.0, metric 1600 (neighbor 501)
>> 06:51:25: network 192.168.1.0, metric 1600 (neighbor 501)
>> r2#
>>
>> Thanks,
>> Chang
>>
>>
>> >From: "Wade Edwards" <wade.edwards@powerupnetworks.com>
>> >To: "ying chang" <ying_c@hotmail.com>
>> >CC: <ccielab@groupstudy.com>
>> >Subject: RE: Manupulate administrative distance
>> >Date: Fri, 1 Mar 2002 13:10:05 -0600
>> >
>> >I think you are not understanding the distance command. The IP address
>> >and wildcard mask is used to change the distance of the routes learned
>> >from the neighbor specified by the IP address and wildcard mask. The
>> IP
>> >address and wildcard mask does not apply to the routes themselves.
>> >
>> >HTH L8r.
>> >
>> > -----Original Message-----
>> >From: ying chang [mailto:ying_c@hotmail.com]
>> >Sent: Friday, March 01, 2002 12:03 PM
>> >To: ccielab@groupstudy.com
>> >Subject: Manupulate administrative distance
>> >
>> >Hi,
>> >
>> >Can someone explain to me why I got 105 instead of 172 and 192 from the
>> >distance command I have in my config? The toplogy is
>> >
>> >OSPF/IGRP redistribution point
>> >(150.100.1.0,150.100.2.0,150.100.50.0)<-150.100.11.0->R2/IGRP<-160.100.
>> 0
>> >.0-->R3/IGRP(172.16.0.0,192.168.1.0)
>> >
>> >IGRP is the only protocol that is used in R2. Config and output are at
>> >the
>> >bottom of the message. I have comments in my config for what I'm trying
>> >to
>> >do.
>> >
>> >Thanks,
>> >Chang
>> >
>> >router igrp 100
>> >timers basic 10 30 30 60
>> >network 150.100.0.0
>> >network 160.100.0.0
>> >distance 105 <-- Change default to 105
>> >distance 130 150.100.0.0 0.0.255.255 sub150 <-- modify 150.100.1.0 and
>> >2.0
>> >to 130
>> >distance 192 192.168.1.0 0.0.0.255 sub192 <-- modify 192.168.1.0 to 192
>> >distance 172 172.160.0.0 0.0.255.255 <-- Doyle's sample does not use
>> >access-list
>> >!
>> >!
>> >ip access-list standard sub150
>> >permit 150.100.1.0 0.0.0.255
>> >permit 150.100.2.0 0.0.0.255
>> >ip access-list standard sub192
>> >permit 192.168.1.0 0.0.0.255
>> >
>> >----------------------------------------
>> >Interfaces:
>> >
>> >r2#siib
>> >Interface IP-Address OK? Method Status
>> >
>> >Prot
>> >ocol
>> >Ethernet0 160.100.77.121 YES NVRAM up
>> >
>> >up
>> >
>> >Ethernet1 unassigned YES NVRAM administratively
>> >down
>> >down
>> >
>> >Serial0 unassigned YES NVRAM administratively
>> >down
>> >down
>> >
>> >Serial1 150.100.11.2 YES NVRAM up
>> >
>> >up
>> >------------------------------------------
>> >Routing table:
>> >
>> >r2#sir
>> >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
>> > E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
>> > i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS
>> >inter
>> >area
>> > * - candidate default, U - per-user static route, o - ODR
>> > P - periodic downloaded static route
>> >
>> >Gateway of last resort is not set
>> >
>> >I 172.160.0.0/16 [105/1600] via 160.100.77.125, 00:00:07, Ethernet0
>> ><---
>> >???
>> > 160.100.0.0/24 is subnetted, 1 subnets
>> >C 160.100.77.0 is directly connected, Ethernet0
>> >I 192.168.1.0/24 [105/1600] via 160.100.77.125, 00:00:07, Ethernet0
>> ><---
>> >???
>> > 150.100.0.0/24 is subnetted, 5 subnets
>> >I 150.100.50.0 [105/160350] via 150.100.11.1, 00:00:04, Serial1
>> >I 150.100.2.0 [130/160350] via 150.100.11.1, 00:00:04, Serial1
>> ><---
>> >Modified
>> >I 150.100.1.0 [130/10576] via 150.100.11.1, 00:00:04, Serial1
>> ><---
>> >Modified
>> >I 150.100.10.0 [105/8576] via 150.100.11.1, 00:00:05, Serial1
>> >C 150.100.11.0 is directly connected, Serial1
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
This archive was generated by hypermail 2.1.4 : Thu Jun 13 2002 - 10:56:50 GMT-3