From: Edwin Wargo (edwin@rsquared.com)
Date: Sun Oct 05 2003 - 14:43:44 GMT-3
Here's a few pretty good links that describe passive
interfaces in various routing protocols:
EIGRP
http://www.cisco.com/en/US/tech/tk365/tk207/technologies_tech_note09186a0080093f0a.shtml
http://www.cisco.com/en/US/tech/tk365/tk207/technologies_q_and_a_item09186a008012dac4.shtml
OSPF
http://www.cisco.com/en/US/tech/tk365/tk480/technologies_q_and_a_item09186a0080094704.shtml#q1
Default Passive Interface (a bit dated but some good
information)
http://www.cisco.com/en/US/products/sw/iosswrel/ps1830/products_feature_guide09186a008008784e.html
IS-IS
http://www.cisco.com/en/US/tech/tk365/tk381/technologies_tech_note09186a008009445a.shtml
http://www.cisco.com/warp/public/97/is-is-ip-config.html
HTH,
Edwin
On Sun, 5 Oct 2003 12:28:39 -0400
"ccie2be" <ccie2be@nyc.rr.com> wrote:
>Passive interface works the same way with Eigrp and igrp
>as it does with
>RIP. I'm not 100% sure what effect it has with link
>state protocols - it
>may prevent link state flooding out of passive interfaces
>but I'm not sure.
>Of course, if you don't need link states flooded out a
>particular interface
>make sure that the subnet of those interfaces aren't
>included under the
>routing process.
>
>HTH, dt
>
>
>----- Original Message -----
>From: "k c" <jwongccie@yahoo.com.hk>
>To: "William Lijewski" <ccie8642@hotmail.com>;
><ccielab@groupstudy.com>
>Sent: Sunday, October 05, 2003 11:36 AM
>Subject: Re: passive interface lo
>
>
>> Thanks for your reply. How about eigrp (and other
>>protocols)? I try to
>debug eigrp, but cannot observe anything?
>>
>> int lo 0
>> ip address 192.168.3.1 255.255.255.224
>>
>> With passive interface lo0
>> 5w2d: IP-EIGRP: 192.168.1.128/27 - do advertise out
>>FastEthernet1/0
>> 5w2d: IP-EIGRP: Int 192.168.1.128/27 metric 28160 -
>>25600 2560
>> 5w2d: IP-EIGRP: 192.168.1.96/27 - do advertise out
>>FastEthernet1/0
>> 5w2d: IP-EIGRP: 192.168.3.0/27 - don't advertise out
>>FastEthernet1/0
>> 5w2d: IP-EIGRP: 192.168.3.0/24 - do advertise out
>>FastEthernet1/0
>> 5w2d: IP-EIGRP: Int 192.168.3.0/24 metric 128256 - 256
>>128000
>> 5w2d: IP-EIGRP: 192.168.1.128/27 - do advertise out
>>FastEthernet1/0
>> 5w2d: IP-EIGRP: Int 192.168.1.128/27 metric 28160 -
>>25600 2560
>> 5w2d: IP-EIGRP: 192.168.1.96/27 - do advertise out
>>FastEthernet1/0
>> 5w2d: IP-EIGRP: 192.168.3.0/27 - don't advertise out
>>FastEthernet1/0
>> 5w2d: IP-EIGRP: 192.168.3.0/24 - do advertise out
>>FastEthernet1/0
>> 5w2d: IP-EIGRP: Int 192.168.3.0/24 metric 128256 - 256
>>128000
>> 5w2d: IP-EIGRP: Processing incoming UPDATE packet
>> 5w2d: IP-EIGRP: Int 192.168.1.32/27 M 30720 - 25600 5120
>>SM 28160 - 25600
>2560
>> 5w2d: IP-EIGRP: Int 80.1.1.0/24 M 158720 - 25600 133120
>>SM 156160 - 25600
>130560
>> 5w2d: IP-EIGRP: Int 81.1.1.0/24 M 158720 - 25600 133120
>>SM 156160 - 25600
>130560
>> 5w2d: IP-EIGRP: Int 192.168.1.0/27 M 33280 - 25600 7680
>>SM 30720 - 25600
>5120
>> 5w2d: IP-EIGRP: Ext 0.0.0.0/0 M 35840 - 25600 10240 SM
>>33280 - 25600 7680
>> 5w2d: IP-EIGRP: Ext 150.150.1.0/24 M 35840 - 25600 10240
>>SM 33280 - 25600
>7680
>> 5w2d: IP-EIGRP: Ext 150.150.2.0/24 M 35840 - 25600 10240
>>SM 33280 - 25600
>7680
>> 5w2d: IP-EIGRP: Ext 11.1.1.0/24 M 35840 - 25600 10240 SM
>>33280 - 25600
>7680
>> 5w2d: IP-EIGRP: Ext 172.168.10.0/24 M 35840 - 25600
>>10240 SM 33280 - 25600
>7680
>> 5w2d: IP-EIGRP: Ext 172.168.64.0/18 M 35840 - 25600
>>10240 SM 33280 - 25600
>7680
>> 5w2d: IP-EIGRP: Ext 150.200.16.0/20 M 35840 - 25600
>>10240 SM 33280 - 25600
>7680
>> 5w2d: IP-EIGRP: Ext 192.168.1.0/24 M 35840 - 25600 10240
>>SM 33280 - 25600
>7680
>> 5w2d: IP-EIGRP: Ext 137.20.20.0/24 M 35840 - 25600 10240
>>SM 33280 - 25600
>7680
>> 5w2d: IP-EIGRP: Ext 150.100.32.2/32 M 35840 - 25600
>>10240 SM 33280 - 25600
>7680
>> 5w2d: IP-EIGRP: Ext 150.100.32.4/32 M 35840 - 25600
>>10240 SM 33280 - 25600
>7680
>> 5w2d: IP-EIGRP: Ext 150.100.32.10/32 M 35840 - 25600
>>10240 SM 33280 -
>25600 7680
>> 5w2d: IP-EIGRP: Int 192.168.1.32/27 metric 30720 - 25600
>>5120
>> 5w2d: IP-EIGRP: Int 80.1.1.0/24 metric 158720 - 25600
>>133120
>> 5w2d: IP-EIGRP: Int 81.1.1.0/24 metric 158720 - 25600
>>133120
>> 5w2d: IP-EIGRP: Int 192.168.1.0/27 metric 33280 - 25600
>>7680
>> 5w2d: IP-EIGRP: Ext 0.0.0.0/0 metric 35840 - 25600 10240
>> 5w2d: IP-EIGRP: Ext 150.150.1.0/24 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 150.150.2.0/24 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 11.1.1.0/24 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 172.168.10.0/24 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 172.168.64.0/18 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 150.200.16.0/20 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 192.168.1.0/24 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 137.20.20.0/24 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 150.100.32.2/32 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 150.100.32.4/32 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 150.100.32.10/32 metric 35840 -
>>25600 10240
>> 5w2d: IP-EIGRP: 192.168.1.128/27 - do advertise out
>>FastEthernet1/0
>> 5w2d: IP-EIGRP: Int 192.168.1.128/27 metric 28160 -
>>25600 2560
>> 5w2d: IP-EIGRP: 192.168.1.96/27 - do advertise out
>>FastEthernet1/0
>> 5w2d: IP-EIGRP: 192.168.3.0/27 - don't advertise out
>>FastEthernet1/0
>> 5w2d: IP-EIGRP: 192.168.3.0/24 - do advertise out
>>FastEthernet1/0
>> 5w2d: IP-EIGRP: Int 192.168.3.0/24 metric 128256 - 256
>>128000
>> 5w2d: IP-EIGRP: Int 192.168.1.32/27 metric 30720 - 25600
>>5120
>> 5w2d: IP-EIGRP: Int 80.1.1.0/24 metric 158720 - 25600
>>133120
>> 5w2d: IP-EIGRP: Int 81.1.1.0/24 metric 158720 - 25600
>>133120
>> 5w2d: IP-EIGRP: Int 192.168.1.0/27 metric 33280 - 25600
>>7680
>> 5w2d: IP-EIGRP: Ext 0.0.0.0/0 metric 35840 - 25600 10240
>> 5w2d: IP-EIGRP: Ext 150.150.1.0/24 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 150.150.2.0/24 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 11.1.1.0/24 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 172.168.10.0/24 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 172.168.64.0/18 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 150.200.16.0/20 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 192.168.1.0/24 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 137.20.20.0/24 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 150.100.32.2/32 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 150.100.32.4/32 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 150.100.32.10/32 metric 35840 -
>>25600 10240
>> 5w2d: IP-EIGRP: Processing incoming UPDATE packet
>> 5w2d: IP-EIGRP: Int 192.168.1.128/27 M 4294967295 -
>>25600 4294967295 SM
>42949672
>> 95 - 25600 4294967295
>> 5w2d: IP-EIGRP: Int 192.168.3.0/24 M 4294967295 - 25600
>>4294967295 SM
>4294967295
>> - 25600 4294967295
>> With "passive interface lo0"
>> 5w2d: IP-EIGRP: 192.168.1.128/27 - do advertise out
>>FastEthernet1/0
>> 5w2d: IP-EIGRP: Int 192.168.1.128/27 metric 28160 -
>>25600 2560
>> 5w2d: IP-EIGRP: 192.168.1.96/27 - do advertise out
>>FastEthernet1/0
>> 5w2d: IP-EIGRP: 192.168.3.0/27 - don't advertise out
>>FastEthernet1/0
>> 5w2d: IP-EIGRP: 192.168.3.0/24 - do advertise out
>>FastEthernet1/0
>> 5w2d: IP-EIGRP: Int 192.168.3.0/24 metric 128256 - 256
>>128000
>> 5w2d: IP-EIGRP: 192.168.1.0/24 - poison advertise out
>>FastEthernet1/0
>> 5w2d: IP-EIGRP: Processing incoming UPDATE packet
>> 5w2d: IP-EIGRP: Int 192.168.1.32/27 M 30720 - 25600 5120
>>SM 28160 - 25600
>2560
>> 5w2d: IP-EIGRP: Int 80.1.1.0/24 M 158720 - 25600 133120
>>SM 156160 - 25600
>130560
>> 5w2d: IP-EIGRP: Int 81.1.1.0/24 M 158720 - 25600 133120
>>SM 156160 - 25600
>130560
>> 5w2d: IP-EIGRP: Int 192.168.1.0/27 M 33280 - 25600 7680
>>SM 30720 - 25600
>5120
>> 5w2d: IP-EIGRP: Ext 0.0.0.0/0 M 35840 - 25600 10240 SM
>>33280 - 25600 7680
>> 5w2d: IP-EIGRP: Ext 150.150.1.0/24 M 35840 - 25600 10240
>>SM 33280 - 25600
>7680
>> 5w2d: IP-EIGRP: Ext 150.150.2.0/24 M 35840 - 25600 10240
>>SM 33280 - 25600
>7680
>> 5w2d: IP-EIGRP: Ext 11.1.1.0/24 M 35840 - 25600 10240 SM
>>33280 - 25600
>7680
>> 5w2d: IP-EIGRP: Ext 172.168.10.0/24 M 35840 - 25600
>>10240 SM 33280 - 25600
>7680
>> 5w2d: IP-EIGRP: Ext 172.168.64.0/18 M 35840 - 25600
>>10240 SM 33280 - 25600
>7680
>> 5w2d: IP-EIGRP: Ext 150.200.16.0/20 M 35840 - 25600
>>10240 SM 33280 - 25600
>7680
>> 5w2d: IP-EIGRP: Ext 192.168.1.0/24 M 35840 - 25600 10240
>>SM 33280 - 25600
>7680
>> 5w2d: IP-EIGRP: 192.168.1.0/24 routing table not updated
>> 5w2d: IP-EIGRP: Ext 137.20.20.0/24 M 35840 - 25600 10240
>>SM 33280 - 25600
>7680
>> 5w2d: IP-EIGRP: Ext 150.100.32.2/32 M 35840 - 25600
>>10240 SM 33280 - 25600
>7680
>> 5w2d: IP-EIGRP: Ext 150.100.32.4/32 M 35840 - 25600
>>10240 SM 33280 - 25600
>7680
>> 5w2d: IP-EIGRP: Ext 150.100.32.10/32 M 35840 - 25600
>>10240 SM 33280 -
>25600 7680
>> 5w2d: IP-EIGRP: Int 192.168.1.32/27 metric 30720 - 25600
>>5120
>> 5w2d: IP-EIGRP: Int 80.1.1.0/24 metric 158720 - 25600
>>133120
>> 5w2d: IP-EIGRP: Int 81.1.1.0/24 metric 158720 - 25600
>>133120
>> 5w2d: IP-EIGRP: Int 192.168.1.0/27 metric 33280 - 25600
>>7680
>> 5w2d: IP-EIGRP: Ext 0.0.0.0/0 metric 35840 - 25600 10240
>> 5w2d: IP-EIGRP: Ext 150.150.1.0/24 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 150.150.2.0/24 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 11.1.1.0/24 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 172.168.10.0/24 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 172.168.64.0/18 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 150.200.16.0/20 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 137.20.20.0/24 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 150.100.32.2/32 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 150.100.32.4/32 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 150.100.32.10/32 metric 35840 -
>>25600 10240
>> 5w2d: IP-EIGRP: 192.168.1.128/27 - do advertise out
>>FastEthernet1/0
>> 5w2d: IP-EIGRP: Int 192.168.1.128/27 metric 28160 -
>>25600 2560
>> 5w2d: IP-EIGRP: 192.168.1.96/27 - do advertise out
>>FastEthernet1/0
>> 5w2d: IP-EIGRP: 192.168.3.0/27 - don't advertise out
>>FastEthernet1/0
>> 5w2d: IP-EIGRP: 192.168.3.0/24 - do advertise out
>>FastEthernet1/0
>> 5w2d: IP-EIGRP: Int 192.168.3.0/24 metric 128256 - 256
>>128000
>> 5w2d: IP-EIGRP: 192.168.1.0/24 - poison advertise out
>>FastEthernet1/0
>> 5w2d: IP-EIGRP: Int 192.168.1.32/27 metric 30720 - 25600
>>5120
>> 5w2d: IP-EIGRP: Int 80.1.1.0/24 metric 158720 - 25600
>>133120
>> 5w2d: IP-EIGRP: Int 81.1.1.0/24 metric 158720 - 25600
>>133120
>> 5w2d: IP-EIGRP: Int 192.168.1.0/27 metric 33280 - 25600
>>7680
>> 5w2d: IP-EIGRP: Ext 0.0.0.0/0 metric 35840 - 25600 10240
>> 5w2d: IP-EIGRP: Ext 150.150.1.0/24 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 150.150.2.0/24 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 11.1.1.0/24 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 172.168.10.0/24 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 172.168.64.0/18 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 150.200.16.0/20 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 137.20.20.0/24 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 150.100.32.2/32 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 150.100.32.4/32 metric 35840 - 25600
>>10240
>> 5w2d: IP-EIGRP: Ext 150.100.32.10/32 metric 35840 -
>>25600 10240
>> 5w2d: IP-EIGRP: Processing incoming UPDATE packet
>> 5w2d: IP-EIGRP: Int 192.168.1.128/27 M 4294967295 -
>>25600 4294967295 SM
>42949672
>> 95 - 25600 4294967295
>> 5w2d: IP-EIGRP: Int 192.168.3.0/24 M 4294967295 - 25600
>>4294967295 SM
>4294967295
>> - 25600 4294967295
>>
>> William Lijewski <ccie8642@hotmail.com> wrote:
>> Setting the Loopback as passive is basically going to
>>stop the router from
>> sending updates to the Loopback. Take a look at the
>>'debug ip rip' output
>> below. This one is when the Loopback is not set as
>>passive.
>>
>> r1#debug ip rip
>> RIP protocol debugging is on
>> r1#clear ip route *
>> r1#
>> 1d13h: RIP: sending request on Loopback0 to
>>255.255.255.255
>> 1d13h: RIP: sending request on Ethernet0 to
>>255.255.255.255
>> r1#
>> 1d13h: RIP: sending v1 flash update to 255.255.255.255
>>via Ethernet0
>> (10.100.10.
>> 1)
>> 1d13h: RIP: build flash update entries
>> 1d13h: subnet 10.1.1.0 metric 1
>> 1d13h: RIP: sending v1 flash update to 255.255.255.255
>>via Loopback0
>> (10.1.1.1)
>> 1d13h: RIP: build flash update entries
>> 1d13h: subnet 10.100.10.0 metric 1
>> r1#
>> 1d13h: RIP: sending v1 update to 255.255.255.255 via
>>Ethernet0
>(10.100.10.1)
>> 1d13h: RIP: build update entries
>> 1d13h: subnet 10.1.1.0 metric 1
>> 1d13h: RIP: sending v1 update to 255.255.255.255 via
>>Loopback0 (10.1.1.1)
>> 1d13h: RIP: build update entries
>> 1d13h: subnet 10.100.10.0 metric 1
>>
>>
>> Notice how its sending updates to the Loopback and the
>>Ethernet. Now we'll
>> make the Loopback passive:
>>
>>
>>
>> r1(config)#router rip
>> r1(config-router)#passive-interface lo 0
>> r1(config-router)#end
>> r1#clear ip route *
>> r1#
>> 1d13h: RIP: sending request on Ethernet0 to
>>255.255.255.255
>> r1#
>> 1d13h: RIP: sending v1 flash update to 255.255.255.255
>>via Ethernet0
>> (10.100.10.
>> 1)
>> 1d13h: RIP: build flash update entries
>> 1d13h: subnet 10.1.1.0 metric 1
>> r1#
>> 1d13h: RIP: sending v1 update to 255.255.255.255 via
>>Ethernet0
>(10.100.10.1)
>> 1d13h: RIP: build update entries
>> 1d13h: subnet 10.1.1.0 metric 1
>>
>>
>> Now that we have made the Loopback passive RIP is no
>>longer sending
>updates
>> to the Loopback. Were saving the router a little bit of
>>work this way. The
>> Loopback address will still be sent out to our
>>neighbors, the router just
>> isn't going to spend time sending usless updates.
>>
>> Bill Lijewski
>> CCIE #8642
>> Network Learning Inc
>> 5 Day R&S CCIE Bootcamp Instructor
>>
>>
>>
>> >From: k c
>> >Reply-To: k c
>> >To: ccielab@groupstudy.com
>> >Subject: passive interface lo
>> >Date: Fri, 3 Oct 2003 19:36:40 +0800 (CST)
>> >
>> >I have seen the command "passive interface lo0"
>>configured in some
>routing
>> >protocols like rip, eigrp, ospf, isis. What does this
>>mean? Loopback is
>not
>> >a physical interface, why make it passive? What is the
>>theory behind?
>> >
>> >!u&V%*(+ &V%k(+!v=l)G VoiceMail Ew*o5|....
>> >http://voicemail.yahoo.com.hk
>> >
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