I think support for /31 masks was introduced in 12.2.8 though I'm
sure someone will correct me if I'm mistaken;)
Dave
s vermill wrote:
MADMAN wrote:
Glad you got it figured out and I hope you learned some
reason(s) not
to do unnumbered. I can't think of and good reasons for it and
if you
If it is a loopback address lets say 192.168.1.2 255.255.255.252 the router
will see the netblock local to the router. Lets say the other end is
192.168.1.1 255.255.255.252 Point-to-point. Try putting a route statement ip
route 192.168.1.1 255.255.255.255 out the interface. This creates a more
Hi Ladrach
I tried with the route statement. it worked perfectly. but the problem is
when i am running the routing protocol. i have given detailed configs for 3
different cases in the previous mails.
Regards
Deepak
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7i=62193t=62134
Deepak N wrote:
HI All
I have simple configuration of HDLC connected back to back.
If i give ip unnumbered at one end and the static ip address at
the other end, I cant ping the either end. But when i give show
ip int brief, it shows the line and protocol are up.
If i give ip unnumbered
Hi Vermill
Now I got the point. So when i am using the numbered interface, the router
tries to reach the next hop via the next hop ip address, in my case it is
behind the directly connected interface.But it has no way of finding the
next hop ip address behind the unnumbered interface. So it was
Deepak N wrote:
Hi Vermill
Now I got the point. So when i am using the numbered
interface, the router tries to reach the next hop via the next
hop ip address, in my case it is behind the directly connected
interface.But it has no way of finding the next hop ip address
behind the
Glad you got it figured out and I hope you learned some reason(s) not
to do unnumbered. I can't think of and good reasons for it and if you
running out of addresses I have an RFC full of them for you;)
Dave
Deepak N wrote:
Hi Vermill
Now I got the point. So when i am using the numbered
MADMAN wrote:
Glad you got it figured out and I hope you learned some
reason(s) not
to do unnumbered. I can't think of and good reasons for it and
if you
running out of addresses I have an RFC full of them for you;)
Dave,
I heard rumor to the effect that Cisco would introduce /31 mask
In mail.net.groupstudy.pro, you wrote:
I heard rumor to the effect that Cisco would introduce /31 mask support
for
serial p-t-p links. Anyone tried that yet? I keep forgeting to when on a
router with shiny new IOS.
It works well on all platforms I've used it on. Introduced in 12.2(2)T,
[EMAIL PROTECTED] (Kaj J. Niemi) wrote:
In mail.net.groupstudy.pro, you wrote:
I heard rumor to the effect that Cisco would introduce /31
mask support for
serial p-t-p links. Anyone tried that yet? I keep
forgeting to when on a
router with shiny new IOS.
It works well on all
Hi Deepak
When you configure ip unnnumbered on an interfaces it looks like an
interface with a /0 mask.
On the other side with a configured ip address on the interface you have a
different mask. So the two connected interfaces don't belong to the same
network.
What you could do is to configure on
Hi Claudio
Thanks for quick response.
But i have tried that options. i defined a static ip route to the network
on the other end through the connecting interface.it did work.
But when i am using the routing protocol, i am not able to ping either end.
But if i make the other end also
Which is failing to get to the other side? The ping (echo) or the ping reply
(echo reply). Pinging could fail for either reason. Debug icmp and you might
get more info.
Also, send us your configs. Help us help you.
Priscilla
Deepak N wrote:
Hi Claudio
Thanks for quick response.
But i
Hi
What kind of routing protocol are you using? Ospf can not build an adjacency
this way.
With other routing protocols you should be able to exchange routing tables.
But you won't be able to send traffic, because the router does not know
where the next-hop address is. So you still need this
Hi all
The following are the configurations of the routers and the ping outputs.
I have given 3 cases.
1) When ip unnumbered at one end and static routes are defined
sdmheadend#sh run
Building configuration...
Current configuration : 1115 bytes
!
version 12.2
service timestamps debug
Hi
Give us a look at the routing table from both routers.
The router with the configured ip address on the Serial interface does not
know how to get to the next hop address.
Do you see in the routing table the next-hop address or the outbound
interface?
see you
Message Posted at:
So it fails when you have numbered on one side and unnumbered on the other
side and you are running RIP?
What did show ip route tell you when the problem occured? Were the
relevant routes in both routers' tables?
What address does sdmheadend use to send the echo? If it's using
172.20.110.10,
HI Claudio
Please find the following for the different cases i mentioned.
Regards
Deepak
1)When ip unnumbered at one end and static routes are defined
sdmheadend#sh ip rou
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O -
Hi
when i did debug ip icmp, i got the message that its unroutable when one
end is numbered and the other end is unnumbered. This is expected because it
doesnt have the next hop ip address to reach. But i expect the same
behaviour when both are unnumbered. But it is able to send the rip updates
Do these labs for better understanding...
http://www.cisco.com/en/US/tech/tk648/tk365/technologies_tech_note09186a
0080094e8d.shtml
WATCH THE WORD WRAP!
Deepak N wrote:
Hi all
The following are the configurations of the routers and the
ping outputs.
I have given 3 cases.
1) When ip
recall that the link between you and whomever is a two host network. if you
were numbering, you would most likely use a /30. even when connecting to the
internet, this link need not use public IP space. Your ISP is most likely
using a static route to you, and you in turn are using a static route
You can use ip unnumbered with or without PPP, depending on how your
provider is set up. You would just use ip unnumbered to the ethernet port
or to a loopback interface, whichever you prefer, I prefer the loopback.
*-Original Message-
*From: richard dumoulin [mailto:[EMAIL PROTECTED]]
Chuck wrote:
recall that the link between you and whomever is a two host
network.
And I would add to that, recall that the link is just a transit for
end-to-end traffic. With the exception of network management, it doesn't
matter what the network-layer addressing is on that link. It carries
Comments inline:
*-Original Message-
*From: Priscilla Oppenheimer [mailto:[EMAIL PROTECTED]]
*Sent: Tuesday, July 16, 2002 1:32 PM
*To: [EMAIL PROTECTED]
*Subject: Re: ip unnumbered [7:48894]
*
*
*Chuck wrote:
*
* recall that the link between you and whomever is a two host
* network
To: [EMAIL PROTECTED]
Subject: RE: ip unnumbered [7:48894]
You can use ip unnumbered with or without PPP, depending on how your
provider is set up. You would just use ip unnumbered to the ethernet port
or to a loopback interface, whichever you prefer, I prefer the loopback
a bit puzzled .
Cheers
Jas
-Original Message-
From: Chuck [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, 17 July 2002 2:15 a.m.
To: [EMAIL PROTECTED]
Subject: Re: ip unnumbered [7:48894]
recall that the link between you and whomever is a two host network. if you
were numbering, you would
From the config I see, here's what I'm interpreting:
Router instructed to start monitoring packets coming in s0.1 as defined in
the CBAC statement corp. Then there's an ACL 100 on the e0/0, going in the
router, but if that's for CBAC, then it's on the wrong interface. CBAC
needs an ACL to
Hi Steve
Here is an extract from the config - access-list 100 controls traffic from
the untrusted section of the company being migrated.
firewall is the name of the ip inspect policy
interface Ethernet0/0
description Sydney Local Ethernet Segment
ip address 172.25.201.1 255.255.0.0
no
not enough info to tell
Need more of the config.
Dennis Cooper wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Hi Steve
Here is an extract from the config - access-list 100 controls traffic from
the untrusted section of the company being migrated.
firewall is the name of
service timestamps debug datetime msec localtime show-timezone
service timestamps log datetime msec localtime show-timezone
service password-encryption
!
hostname firewall
!
boot system flash c3620-io-mz.120-3.T3.bin
logging buffered 10 debugging
enable secret 5 $1$hqZ4$k9Mvt5yfvbpipYmFGbTSS/
show me the configs
Dennis Cooper wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Hi guys
The scenario is two customer networks merging in the same building and we
have a Cisco 3620 in between the two LAN networks. (E0/0 and E1/0)
S0/0 ---3620---E0/0
Not sure what you're asking there?
The address you're going to is within your Ethernet subnet. Traceroute
shouldn't take too long (no hops).
I take it you mean this is the remote router.
I take it you made that config up (typos and all :-) ). Paste the real
thing for both ends.
What does
Let's say you want to run frame relay or hdlc using serial interfaces on two
routers, but don't have any ip addresses to waste, you can use the ip
addresses of the ethernet or token ring interfaces as the ip addresses for
your serial interfaces. This stuff is easy to look up on Cisco's web site.
You tie your serial (generally) to a LAN or loopback interface instead
of giving the serial interface it's own address. For this scenerio just
don't do it, need addresses, see RFC 1918.
Dave
birdy wrote:
Dear all
can anyone tell me what is IP unnumbered ?
Regards, birdy
--
David
I think a lot of the ISPs are doing this for the smaller customers..
For example, we put in on the side, an internet router for a small law firm
using MCI and instead of giving us an address for the
serial interface, they wanted me to ip unnumber it from ethernet port.
Saves them some ip
]
Subject: Re: IP unnumbered [7:18250]
Dave,
I agree totally with your statement, however, I don't understand why you say
that if you use ip unnumbered pointing to a LoopBack interface that
nullifies the point of using unnumbered (to save IPs). You can still use a
single IP address on a LoopBack
]
Subject: Re: IP unnumbered [7:18250]
Dave,
I agree totally with your statement, however, I don't understand why you
say
that if you use ip unnumbered pointing to a LoopBack interface that
nullifies the point of using unnumbered (to save IPs). You can still use a
single IP address on a LoopBack
Hi
Instead of using a numbered link you can use ip unnumbered to connect
sites.
Example:
Router A:
interface fastethernet 0
ip address 10.100.2.1 255.255.255.0
interface serial 0
ip unnumbered fasthethernet 0
Router B:
interface fastethernet 0
ip address 10.100.31 255.255.255.0
Brett gives a good example that will work just fine but I would not
recommend using IP unnumbered. With RFC 1918 you have more IP addesses
than your going to need so no problems with using registered addresses
on p-to-p links. troubleshooting also becomes trickier but if you
insist on using
Dave,
I agree totally with your statement, however, I don't understand why you say
that if you use ip unnumbered pointing to a LoopBack interface that
nullifies the point of using unnumbered (to save IPs). You can still use a
single IP address on a LoopBack not waste more by putting separate
At this point, it think it would be good to mention that (IMHO) it's best to
use the LoopBack interface for ip unnumbered because it can never go
down..
In the config snipet you gave, your Serial0 couldn't communicate if
FastEthernet0 went down.
I do believe that with some version of 12.x,
Agree, you don't use as many address with LB's as p-to-p networks but
the primary point I was trying to make before I rambled is that there is
really no good reason IMHO to ip unnumbered.
Dave
Michael L. Williams wrote:
Dave,
I agree totally with your statement, however, I don't
Sure, IP unnumbered is frequently used by ISP's to save address space and
for ease of configuration. Lets say you have a 7513 with 280 T1 customers
on it, that would mean wasting 280 /30 IP blocks just on interface transit,
so why use those IP's if you don't have a specific reason to? That is
When IP addresses are hard to come by (remember: a /30 subnet takes 4
addresses). When you don't want to deal with administering tons of /30
subnets that would comprise the WAN links.
There are probably other reasons. These were the first to come to mind.
Ken Diliberto
CCNA, CCNP, Ericsson E1
you might use it if you had say an access-server
e.g you got group-async 1 and group-async
the router wont let you do 'ip address 10.0.0.1 255.0.0.0 on both interfaces
so instead you would assign 10.0.0.1 to loopback 0
and then in group-async 1 2
ip unnumbered loopback 0
thus giving them both
Another advantage of IP unumbered, is if you have say 250 T1 customers
hanging off a router, and you default router them out there serial
interface:
ip route 0.0.0.0 0.0.0.0 s0
then, if you ever want to move customers to another router, you don't have
to have access to there router to do
You lose the ability to troubleshoot if link goes down. Cannot ping because
there is no IP address to ping.
Heather Buri
csc Technology Services - Houston
Phone: (713)-961-8592
Fax:(713)-961-8249
Mobile:
Alpha Page:
Mailing:1360 Post Oak Blvd
To elaborate on this, if via monitoring you notice pings start to fail,
you do not know if the problem is with the serial or lan interface. i
have seen a few of these where customers lan maintenance caused wan
failure.
Bri
On Mon, 19 Mar 2001, Buri, Heather H wrote:
You lose the
Karl, Tom,
I think you are both mistaken--in fact, RFC 2328 contains multiple
references to unnumbered point-to-point links and what should be done about
them when developing an OSPF implementation.
The router doesn't need an exact interface IP address on a point-to-point
link in order to
01, 2001 3:45 PM
To: Pamela Forsyth; [EMAIL PROTECTED]; [EMAIL PROTECTED]
Subject: RE: IP unnumbered and OSPF
From the Cisco Press book:
"When an unnumbered interface is configured, it references another interface
... When enabling OSPF on the unnumbered int with the network command
I guess you could do that too...
-Original Message-
From: Montgomery, Robert WARCOM Contractor
[mailto:[EMAIL PROTECTED]]
Sent: Thursday, February 01, 2001 2:36 PM
To: Karl R. West; [EMAIL PROTECTED]
Subject: RE: IP unnumbered and OSPF
Why wouldn't you just use wildcards to indicated
Greetings Karl
I can't remember exactly where I read that , but I did. More specifically
you can't have ip unnumbered on an interface running OSPF because there is
no address to be neighbors with.
If what you want to do is have a router with some ospf interfaces and some
other interface not
Thanks, I thought so too but someone pointed me to this link
http://www.cisco.com/warp/public/104/ospfdb1.html
-Original Message-
From: Tom Pruneau [mailto:[EMAIL PROTECTED]]
Sent: Thursday, February 01, 2001 2:08 AM
To: Karl R. West; [EMAIL PROTECTED]
Subject: Re: IP unnumbered
Why wouldn't you just use wildcards to indicated the exact interface(s)?
-Original Message-
From: Karl R. West [mailto:[EMAIL PROTECTED]]
Sent: Thursday, February 01, 2001 11:23 AM
To: 'Tom Pruneau'; [EMAIL PROTECTED]
Subject: RE: IP unnumbered and OSPF
Thanks, I thought so too
nting."
-Original Message-
From: Pamela Forsyth [mailto:[EMAIL PROTECTED]]
Sent: Thursday, February 01, 2001 1:07 PM
To: [EMAIL PROTECTED]
Subject: Re: IP unnumbered and OSPF
Karl, Tom,
I think you are both mistaken--in fact, RFC 2328 contains multiple
references to unnumbered point-to-p
yth [EMAIL PROTECTED], [EMAIL PROTECTED],
[EMAIL PROTECTED]
From:"Montgomery, Robert WARCOM Contractor" [EMAIL PROTECTED]
Date:Thu, 1 Feb 2001 12:45:04 -0800
Subject: RE: IP unnumbered and OSPF
From the Cisco Press book:
"When an unnumbered interface is configured, it ref
: [EMAIL PROTECTED] (bcc: JENNY
MCLEOD/NSO/CSDA)
Subject: Re: IP Unnumbered.
There is one huge disadvantage. If the ether
segment goes down in an ip
unnumbered setup, then even if everything is
physically ok on the serial
link associated, that serial link will become
unusable
Advisable to use it over a point to point Links.
Thangavel
- Original Message -
From: Brian [EMAIL PROTECTED]
To: Erick B. [EMAIL PROTECTED]
Cc: Gunjan Mathur at 9netave [EMAIL PROTECTED]; [EMAIL PROTECTED]
Sent: Monday, October 16, 2000 5:41 PM
Subject: Re: IP Unnumbered.
unnumbered
I'm no
expert, but I have played with it.
We
have a lab with an old 3000 token ring
router, back-to-back with a 2500 ethernet
router. The 3000 is running IOS 9.x and
the
2500 is running 11.2. The 3000 is on
a
subnet with another router which is our
link
into the Campus Area Network.
With
Ip unnumbered preserves IP addresses. It
allows a port to "borrow" an IP address from another Port on the same device.
(usually the Loopback, can be any, but Loopback stays "up")
It's great for point to point connections.
ISDN , Frame Relay etc..
Jon
Advantages: Saves on IP address space if you don't
have networks to spare.
Disadvantages: Harder to troubleshoot problems since
you can't ping the unnumbered interface to see if it's
down, etc.
--- Gunjan Mathur at 9netave [EMAIL PROTECTED]
wrote:
Hi,
Can somebody tell me Advantages
believe that is not the case.
Anyone else?
Original Message Follows
From: "Ray Mosely" [EMAIL PROTECTED]
Reply-To: "Ray Mosely" [EMAIL PROTECTED]
To: "net974 at Yahoo" [EMAIL PROTECTED], [EMAIL PROTECTED]
Subject: RE: IP Unnumbered.
Date: Mon, 16 Oct 2000 10:21:
There is one huge disadvantage. If the ether segment goes down in an ip
unnumbered setup, then even if everything is physically ok on the serial
link associated, that serial link will become unusable. From a monitoring
perspective, unnumbered is a bad idea. I suspect some people use it to
save
unnumbered interfaces also present design problems when designing a
scalable IGP.
Brian
On Mon, 16 Oct 2000, Erick B. wrote:
Advantages: Saves on IP address space if you don't
have networks to spare.
Disadvantages: Harder to troubleshoot problems since
you can't ping the unnumbered
ot; [EMAIL PROTECTED]
To: Gunjan Mathur at 9netave [EMAIL PROTECTED]
cc: [EMAIL PROTECTED] (bcc: JENNY MCLEOD/NSO/CSDA)
Subject: Re: IP Unnumbered.
There is one huge disadvantage. If the ether segment goes down in an ip
unnumbered setup, then even if everything is physically ok on the se
Thanks Ms. Jenny. I was wondering whether loopback was an option. The
numbering of the Unumbered was getting to me. :)
Dale CCNA
Original Message Follows
From: [EMAIL PROTECTED]
Reply-To: [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
Subject: Re: IP Unnumbered.
Date: Tue, 17 Oct 2000 11:25:13
There is one huge disadvantage. If the ether segment goes down in an ip
unnumbered setup, then even if everything is physically ok on the serial
link associated, that serial link will become unusable. From a monitoring
perspective, unnumbered is a bad idea. I suspect some people use it to
save
Frame-relay providers are not at all concerneted with
your layer 3 addressing (IP). They are strickly involved
with layer2 in this case your DLCI. All routing in their
network is based on the DLCI not the IP. The router in
the customer network will make the IP routing decisions
which in turn are
On Wed, 19 Jul 2000, Niraj Palikhey wrote:
Hi,
I am trying to understand why a serial connection (s0) is not assigned an ip
address to connect with the service provider when configured for frame
relay.
Because you don't need to assign a PtP link its own IP address. The
traffic can really
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
Justin Marcus
Sent: Wednesday, June 07, 2000 4:41 PM
To: ALI SHEERAZ
Cc: [EMAIL PROTECTED]
Subject: Re: ip unnumbered
if your ethernet0 is 10.0.0.1
and you make your serial0 have
Yes, provided your ethernet has a valid ip address.
It is usually allocated by your ISP.
For Ex.
your netblock - 202.35.2.0/29
ISP side - their T1 interface 204.208.22.1
ISPside - IP route 202.35.2.0 255.255.255.248 204.208.22.1
your side - T1 interface , S0 unnumbered
your side - Ethernet
jeongwoo,
Simply put "ip unnumbered" allows you to use the network or
subnet address of the local LAN -interface(i.e e0, t0) as the routers
network or subnetwork address for point-to-point links.
This basically helps you conserve address space by letting you use the
already
Hi,
Here you go...
To conserve IP addresses, configure the asynchronous interfaces as
unnumbered, and assign the IP address of the loopback interface or an
ethernet interface to them.
!
interface ethernet 0
ip address 192.0.0.5 255.255.255.0
!
interface serial 0
ip unnumbered ethernet 0
The "ip unnumbered" configuration command allows you to enable IP processing
on a serial interface without assigning it an explicit IP address. This is a
good way to conserve network and address space.
Consider a class B network subnetted with eight bits. Every interface in the
network
Another thought -
You want to keep in mind though, that for troubleshooting purposes, you lose
the ability to ping the serial interface because it is ip unnumbered. (IE
you would be pinging the lan interface not the serial interface.)
Scott Chapin CCNA
-Original Message-
From: [EMAIL
on 07/06/2000 09:10
---
Justin Marcus [EMAIL PROTECTED] on 07/06/2000 21:11:11
Please respond to Justin Marcus [EMAIL PROTECTED]
To: ALI SHEERAZ [EMAIL PROTECTED]
cc: [EMAIL PROTECTED] (bcc: JENNY MCLEOD/NSO/CSDA)
Subject: Re: ip unnumbered
if your ethernet0
Is does mean that ip unnumbered can't be used if we use point to multipoit
link such as Frame Relay or ATM ?
--
From: ALI SHEERAZ[SMTP:[EMAIL PROTECTED]]
Reply To: ALI SHEERAZ
Sent: Tuesday, June 06, 2000 5:08 PM
To: [EMAIL PROTECTED]
Subject: Re: ip
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