From: Michael Snyder (msnyder@revolutioncomputer.com)
Date: Mon Feb 23 2004 - 12:10:22 GMT-3
I have an answer.
For testing purposes, set the all the admin distances of the protocols
in question to a common value (don't forget to set them back when done).
If you have a hidden loop on any router, it will show up as a duplicate
route once you have cleared the routing table.
Figure out your needed fixes, tags or scoped admin distances for
specific routes, and move on.
Let's call this technique the `Snyder duplicate route check` sdrc for
short.
-----Original Message-----
From: Yasser Aly [mailto:blackyeyes00@hotmail.com]
Sent: Monday, February 23, 2004 7:23 AM
To: Colin.Fowlie@aliant.ca; karim_ccie@hotmail.com;
msnyder@revolutioncomputer.com; ccielab@groupstudy.com
Subject: RE: Routing loops detection [Re: Checking the Lab Work]
Hi Colin,
I tried using this command before and in some cases it will not detect
the
loop while it exists.
An example when Two routers consider eachother as the next-hop for a
certain
destination, here no routing updates are representing the loop where if
you
did a traceroute you will detect it.
Regards,
Yasser
>From: "Fowlie, Colin" <Colin.Fowlie@aliant.ca>
>Reply-To: "Fowlie, Colin" <Colin.Fowlie@aliant.ca>
>
>I would recommend running "debug ip routing" and then watching for
flapping
>routes. This is also helpful to watch the effect of your routing
protocol
>redistribution.
>
>-Colin
>
>-----Original Message-----
>From: Karim [mailto:karim_ccie@hotmail.com]
>Sent: Saturday, February 21, 2004 4:17 PM
>To: Yasser Aly; msnyder@revolutioncomputer.com; ccielab@groupstudy.com
>Subject: Routing loops detection [Re: Checking the Lab Work]
>
>Hi all,
>I have the same concern about detecting routing loops especially after
>finishing the redistribution configurations.
>Could someone help please.
>
>Regards,
>Karim.
>
>
>----- Original Message -----
>From: "Yasser Aly" <blackyeyes00@hotmail.com>
>To: <msnyder@revolutioncomputer.com>; <ccielab@groupstudy.com>
>Sent: Friday, February 20, 2004 8:28 PM
>Subject: RE: Checking the Lab Work
>
>
> > Hi group,
> >
> > Would you kindly share us with your visions on time saving
techniques
>to
> > detect a routing loop ?
> >
> > Regards,
> > Yasser
> >
> >
> > >From: "Michael Snyder" <msnyder@revolutioncomputer.com>
> > >You don't.
> > >
> > >This is simply checking the routing table for present routes.
> > >
> > >A hybrid technique would be needed to test reachability and routing
> > >table contents.
> > >
> > >
> > >
> > >-----Original Message-----
> > >From: Yasser Aly [mailto:blackyeyes00@hotmail.com]
> > >Sent: Friday, February 20, 2004 12:10 PM
> > >To: msnyder@revolutioncomputer.com; ccielab@groupstudy.com
> > >Cc: ahmed.mustafa@sbcglobal.net
> > >Subject: RE: Checking the Lab Work
> > >
> > >
> > >Hello,
> > >
> > > I have two questions:
> > >
> > >1) How to verify reachability for all your routes on the 3550
switch. I
> > >tried tclsh but the command was not accepted on it ?
> > >
> > >2) If you rely on the procedure described below it will be
misleading.
> > >Example, if you have a routing loop for a certain route, you will
have
>a
> > >
> > >route in the sh ip route for the looped route, however you will not
be
> > >able
> > >to detect that it is looped and might think everything is ok if you
>rely
> > >
> > >only that the route show up in the routing table.
> > >
> > >This leads to the question: How to detect that you have a routing
loop
> > >with
> > >one of your routes ?
> > >
> > >Regards,
> > >Yasser
> > >
> > > >From: "Michael Snyder" <msnyder@revolutioncomputer.com>
> > > >
> > > >Here's a repost of the igp grading script I wrote last year.
> > > >
> > > >It's for people with a rack full of 2500`s and don't have access
to
> > > >tclsh.
> > > >
> > >
>
>-----------------------------------------------------------------------
> > >-
> > > >--
> > > >
> > > >I was working on a lab this morning, and for some reason my three
way
> > > >redistribution wasn't working.
> > > >
> > > >After jumping router to router for 30 minutes, I thought gee I
wish I
> > > >had a command to show me every missing route.
> > > >
> > > >I made a script to do this; I'll walk you thru how I composed the
> > > >script. It took me about 5 minutes.
> > > >
> > > >Here's some benefits of the script.
> > > >
> > > >1) Can't be fooled by a default route.
> > > >2) Can't be fooled by the wrong mask size.
> > > >3) Assumes that the route should be present.
> > > >
> > > >Generates output only if it's missing.
> > > >
> > > >
> > >
>
>-----------------------------------------------------------------------
> > >-
> > > >--
> > > >
> > > >First I did a `show run | i ip address`
> > > >
> > > >And pasted the results to notepad from every router.
> > > >
> > > >
> > >
>
>-----------------------------------------------------------------------
> > >-
> > > >--
> > > >
> > > > ip address 170.1.1.1 255.255.255.255
> > > > ip address 150.50.200.1 255.255.255.0
> > > > ip address 170.1.150.1 255.255.255.0
> > > >
> > > > ip address 170.1.2.2 255.255.255.255
> > > > ip address 172.16.1.1 255.255.255.0
> > > > ip address 172.16.3.1 255.255.255.0
> > > > ip address 172.16.2.1 255.255.255.0
> > > > ip address 172.16.0.1 255.255.255.0
> > > > no ip address
> > > > no ip address
> > > > ip address 170.1.100.2 255.255.255.0
> > > > ip address 170.1.150.2 255.255.255.0
> > > > ip address 150.50.9.5 255.255.255.252
> > > >
> > > > ip address 170.1.4.4 255.255.255.255
> > > > ip address 192.168.10.1 255.255.255.0
> > > > no ip address
> > > > ip address 170.1.100.4 255.255.255.0
> > > > no ip address
> > > >
> > > > ip address 170.1.5.5 255.255.255.255
> > > > ip address 170.1.200.5 255.255.255.224
> > > > no ip address
> > > > ip address 170.1.100.5 255.255.255.0
> > > > no ip address
> > > > no ip address
> > > >
> > > > ip address 170.1.6.6 255.255.255.255
> > > > ip address 170.1.200.6 255.255.255.224
> > > > no ip address
> > > > ip address 170.1.100.6 255.255.255.0
> > > > ip address 170.1.32.6 255.255.255.0
> > > > no ip address
> > > >
> > > > ip address 170.1.7.7 255.255.255.255
> > > > ip address 170.1.200.7 255.255.255.224
> > > > ip address 170.1.24.7 255.255.255.0
> > > >
> > > > ip address 170.1.8.8 255.255.255.255
> > > > ip address 150.50.4.8 255.255.255.0
> > > > ip address 170.1.24.8 255.255.255.0
> > > >
> > > > ip address 170.1.9.9 255.255.255.255
> > > > ip address 170.1.32.9 255.255.255.0
> > > > no ip address
> > > > ip address 170.1.15.9 255.255.255.192
> > > >
> > > >
> > > >
> > >
>
>-----------------------------------------------------------------------
> > >-
> > > >--
> > > >
> > > >
> > > >Next in notepad, I did a replace all of `no ip address` with a
null
> > > >string. Then I went thru the listing deleting the empty lines.
> > > >
> > > >
> > >
>
>-----------------------------------------------------------------------
> > >-
> > > >--
> > > >
> > > > ip address 170.1.1.1 255.255.255.255
> > > > ip address 150.50.200.1 255.255.255.0
> > > > ip address 170.1.150.1 255.255.255.0
> > > > ip address 170.1.2.2 255.255.255.255
> > > > ip address 172.16.1.1 255.255.255.0
> > > > ip address 172.16.3.1 255.255.255.0
> > > > ip address 172.16.2.1 255.255.255.0
> > > > ip address 172.16.0.1 255.255.255.0
> > > > ip address 170.1.100.2 255.255.255.0
> > > > ip address 170.1.150.2 255.255.255.0
> > > > ip address 150.50.9.5 255.255.255.252
> > > > ip address 170.1.4.4 255.255.255.255
> > > > ip address 192.168.10.1 255.255.255.0
> > > > ip address 170.1.100.4 255.255.255.0
> > > > ip address 170.1.5.5 255.255.255.255
> > > > ip address 170.1.200.5 255.255.255.224
> > > > ip address 170.1.100.5 255.255.255.0
> > > > ip address 170.1.6.6 255.255.255.255
> > > > ip address 170.1.200.6 255.255.255.224
> > > > ip address 170.1.100.6 255.255.255.0
> > > > ip address 170.1.32.6 255.255.255.0
> > > > ip address 170.1.7.7 255.255.255.255
> > > > ip address 170.1.200.7 255.255.255.224
> > > > ip address 170.1.24.7 255.255.255.0
> > > > ip address 170.1.8.8 255.255.255.255
> > > > ip address 150.50.4.8 255.255.255.0
> > > > ip address 170.1.24.8 255.255.255.0
> > > > ip address 170.1.9.9 255.255.255.255
> > > > ip address 170.1.32.9 255.255.255.0
> > > > ip address 170.1.15.9 255.255.255.192
> > > >
> > > >
> > > >
> > > >
> > >
>
>-----------------------------------------------------------------------
> > >-
> > > >--
> > > >
> > > >
> > > >This lab uses a summary address of 172.16.0.0/22, so I chose to
pull
> > >out
> > > >the 172.16.1.1/24 routes and use the summary instead.
> > > >
> > > >Here's a important part, I needed a unique post-delimiter on the
>ends
> > > >of the statements for text search and replace later. So I
appended
>the
> > > >` char to the ends of the statements by hand. Each statement
begins
> > >the
> > > >same `ip address` text, so I don't need a pre-delimiter here.
> > > >
> > > >
> > >
>
>-----------------------------------------------------------------------
> > >-
> > > >--
> > > >
> > > >
> > > >
> > > > ip address 170.1.1.1 255.255.255.255 `
> > > > ip address 150.50.200.1 255.255.255.0 `
> > > > ip address 170.1.150.1 255.255.255.0 `
> > > > ip address 170.1.2.2 255.255.255.255 `
> > > > ip address 172.16.0.0 255.255.252.0 `
> > > > ip address 170.1.100.2 255.255.255.0 `
> > > > ip address 170.1.150.2 255.255.255.0 `
> > > > ip address 150.50.9.5 255.255.255.252 `
> > > > ip address 170.1.4.4 255.255.255.255 `
> > > > ip address 192.168.10.1 255.255.255.0 `
> > > > ip address 170.1.100.4 255.255.255.0 `
> > > > ip address 170.1.5.5 255.255.255.255 `
> > > > ip address 170.1.200.5 255.255.255.224 `
> > > > ip address 170.1.100.5 255.255.255.0 `
> > > > ip address 170.1.6.6 255.255.255.255 `
> > > > ip address 170.1.200.6 255.255.255.224 `
> > > > ip address 170.1.100.6 255.255.255.0 `
> > > > ip address 170.1.32.6 255.255.255.0 `
> > > > ip address 170.1.7.7 255.255.255.255 `
> > > > ip address 170.1.200.7 255.255.255.224 `
> > > > ip address 170.1.24.7 255.255.255.0 `
> > > > ip address 170.1.8.8 255.255.255.255 `
> > > > ip address 150.50.4.8 255.255.255.0 `
> > > > ip address 170.1.24.8 255.255.255.0 `
> > > > ip address 170.1.9.9 255.255.255.255 `
> > > > ip address 170.1.32.9 255.255.255.0 `
> > > > ip address 170.1.15.9 255.255.255.192 `
> > > >
> > > >
> > > >
> > > >
> > >
>
>-----------------------------------------------------------------------
> > >-
> > > >--
> > > >
> > > >Here's the payoff. Using notepad, replace all `ip address` with
>`show
> > > >ip route` Also replace our delimiting char ` with `| i not`
> > > >
> > > >
> > >
>
>-----------------------------------------------------------------------
> > >-
> > > >--
> > > >
> > > > show ip route 170.1.1.1 255.255.255.255 | i not
> > > > show ip route 150.50.200.1 255.255.255.0 | i not
> > > > show ip route 170.1.150.1 255.255.255.0 | i not
> > > > show ip route 170.1.2.2 255.255.255.255 | i not
> > > > show ip route 172.16.0.0 255.255.252.0 | i not
> > > > show ip route 170.1.100.2 255.255.255.0 | i not
> > > > show ip route 170.1.150.2 255.255.255.0 | i not
> > > > show ip route 150.50.9.5 255.255.255.252 | i not
> > > > show ip route 170.1.4.4 255.255.255.255 | i not
> > > > show ip route 192.168.10.1 255.255.255.0 | i not
> > > > show ip route 170.1.100.4 255.255.255.0 | i not
> > > > show ip route 170.1.5.5 255.255.255.255 | i not
> > > > show ip route 170.1.200.5 255.255.255.224 | i not
> > > > show ip route 170.1.100.5 255.255.255.0 | i not
> > > > show ip route 170.1.6.6 255.255.255.255 | i not
> > > > show ip route 170.1.200.6 255.255.255.224 | i not
> > > > show ip route 170.1.100.6 255.255.255.0 | i not
> > > > show ip route 170.1.32.6 255.255.255.0 | i not
> > > > show ip route 170.1.7.7 255.255.255.255 | i not
> > > > show ip route 170.1.200.7 255.255.255.224 | i not
> > > > show ip route 170.1.24.7 255.255.255.0 | i not
> > > > show ip route 170.1.8.8 255.255.255.255 | i not
> > > > show ip route 150.50.4.8 255.255.255.0 | i not
> > > > show ip route 170.1.24.8 255.255.255.0 | i not
> > > > show ip route 170.1.9.9 255.255.255.255 | i not
> > > > show ip route 170.1.32.9 255.255.255.0 | i not
> > > > show ip route 170.1.15.9 255.255.255.192 | i not
> > > >
> > > >
> > >
>
>-----------------------------------------------------------------------
> > >-
> > > >--
> > > >
> > > >Ok, lets try it on R4.
> > > >
> > > >I use four terminal windows, so I cut and paste to all four at
once,
> > >and
> > > >read the results when done. It's really telling when you see the
>same
> > > >missing route on three of the four routers.
> > > >
> > > >Another thing, if route shouldn't show up on any router, replace
the
>`i
> > > >not` with `e not`
> > > >
> > >
>
>-----------------------------------------------------------------------
> > >-
> > > >--
> > > >
> > > >R4#
> > > >R4#
> > > >R4# show ip route 170.1.1.1 255.255.255.255 | i not
> > > >R4# show ip route 150.50.200.1 255.255.255.0 | i not
> > > >% Network not in table
> > > >
> > > >R4# show ip route 170.1.150.1 255.255.255.0 | i not
> > > >R4# show ip route 170.1.2.2 255.255.255.255 | i not
> > > >R4# show ip route 172.16.0.0 255.255.252.0 | i not
> > > >R4# show ip route 170.1.100.2 255.255.255.0 | i not
> > > >R4# show ip route 170.1.150.2 255.255.255.0 | i not
> > > >R4# show ip route 150.50.9.5 255.255.255.252 | i not
> > > >% Network not in table
> > > >
> > > >R4# show ip route 170.1.4.4 255.255.255.255 | i not
> > > >R4# show ip route 192.168.10.1 255.255.255.0 | i not
> > > >R4# show ip route 170.1.100.4 255.255.255.0 | i not
> > > >R4# show ip route 170.1.5.5 255.255.255.255 | i not
> > > >R4# show ip route 170.1.200.5 255.255.255.224 | i not
> > > >% Subnet not in table
> > > >
> > > >R4# show ip route 170.1.100.5 255.255.255.0 | i not
> > > >R4# show ip route 170.1.6.6 255.255.255.255 | i not
> > > >R4# show ip route 170.1.200.6 255.255.255.224 | i not
> > > >% Subnet not in table
> > > >
> > > >R4# show ip route 170.1.100.6 255.255.255.0 | i not
> > > >R4# show ip route 170.1.32.6 255.255.255.0 | i not
> > > >R4# show ip route 170.1.7.7 255.255.255.255 | i not
> > > >% Subnet not in table
> > > >
> > > >R4# show ip route 170.1.200.7 255.255.255.224 | i not
> > > >% Subnet not in table
> > > >
> > > >R4# show ip route 170.1.24.7 255.255.255.0 | i not
> > > >% Subnet not in table
> > > >
> > > >R4# show ip route 170.1.8.8 255.255.255.255 | i not
> > > >% Subnet not in table
> > > >
> > > >R4# show ip route 150.50.4.8 255.255.255.0 | i not
> > > >% Network not in table
> > > >
> > > >R4# show ip route 170.1.24.8 255.255.255.0 | i not
> > > >% Subnet not in table
> > > >
> > > >R4# show ip route 170.1.9.9 255.255.255.255 | i not
> > > >R4# show ip route 170.1.32.9 255.255.255.0 | i not
> > > >R4# show ip route 170.1.15.9 255.255.255.192 | i not
> > > >R4#
> > > >
> > > >
> > >
>
>-----------------------------------------------------------------------
> > >-
> > > >--
> > > >
> > > >There's my missing routes!!! For some reason rip isn't making it
to
> > > >ospf on R4.
> > > >
> > > >
> > > >-----Original Message-----
> > > >From: Ahmed Mustafa [mailto:ahmed.mustafa@sbcglobal.net]
> > > >Sent: Wednesday, February 18, 2004 9:44 PM
> > > >To: ccielab@groupstudy.com
> > > >Subject: Checking the Lab Work
> > > >
> > > >Guys,
> > > >
> > > >What is the easiest way to check the lab work. This is the most
> > > >important
> > > >task especially if one is taking a real lab.
> > > >
> > > >I mean what is the best way to find out that you are seeing all
the
> > > >routes in
> > > >your routers that are you are supposed to be seeing, and pinging
all
> > >the
> > > >interfaces making sure that there is no loss of connectivity. I
know
> > > >that one
> > > >can do this from each router to see what routes are seen and
whether
> > > >they are
> > > >pingable
> > > >Is there any work around?
> > > >
> > > >Thanks,
> > > >
> > > >Ahmed
> > > >
> > >
>
>_______________________________________________________________________
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This archive was generated by hypermail 2.1.4 : Fri Mar 05 2004 - 07:13:55 GMT-3