Can't ping interface... 2

[wannaciscobe]

Hi,
I'm sorry to ask this probably simple question but here goes:

I set up a "learning lab" at home consisting of 3 2501's and one 2916xl and one linksys workgroup switch. Here is what it looks like
2501-----2501------2501
| |
| |
2900 WG Switch
| |
| |
Host 1 Host 2


I'm using rip v1 and I can ping all serial interfaces from all other routers.
I can ping from both hosts to whatever router they are connected to...i.e...E0 or S0 or S1.

What I cannot do is:
Ping from either host to any other interface on the routers.

Is their some obvious thing I'm missing?

Thanks,
Bob

 

[CCIEWANNABE]

Does the network and the source interfaces have the same subnet mask? The router will drop the request unless you have support for host routes.

There can be other issues to. Rip does not carry subnet masks when advertising. Confirm you settings? Ping is very useful in indicating a problem between a source and destination, but is not useful at pinpointing the problem. Start with the physical layer.

Use the
#show IP interface Brief

#show ip route

#show ip protocols.
Route once; switch many

 

[wybnormal]

Hold on a second.. RIP does not carry a mask per say, it DOES assume a default mask.. ie.. classFULL mask.

RIP 2 DOES carry subnet information so it's CLASSLESS.

A blanket statement that RIP does not carry subnet information is not quite correct and on a CCNP exam will cost you a gime question.

You are on the right trail with the SHOW IP ROUTE ... see who can see who and how.

Here is a very good link and info for starting to troubleshoot IP

http://www.cisco.com/warp/public/779/smbiz/service/troubleshooting/ts_ip.htm

MikeS
Find me at

http://www.packetattack.com

"The trouble with giving up civil rights is that you never get them back"

 

[wannaciscobe]

Thanks to you both for taking the time to help me....I know I can solve it with expert assistance like this...

bob

 

[CCIEWANNABE]

Wybnormal your wrong Rip does not carry subnet mask information in its routing updates. Because it doesn't carry any subnet information, it’s incapable of supporting VLSM. In RIP version one when two subnet values don’t match, the updates get dropped. Rip2 does pick the subnet masks of each subnet and will advertise to RIP2 neighbors.
Rip and RIP2 are two different protocols so you would have answered that question incorrectly wybnormal. He stated RIP not RIP version 2. RIP and RIP two are totally different topics.
Route once; switch many

 

[wybnormal]

Read this carefully-
"A blanket statement that RIP does not carry subnets is not quite correct " Notice that I did NOT say it was utterly wrong, just that it's misleading.

and then this-
"Rip does not carry subnet masks when advertising."

I stand by what I said, a blanket statement that RIP does not carry subnetting is incorrect. A more correct statement is that RIP1 does not carry subnet information.

You might think I'm being picky here but when talking to engineering at Cisco, 3Com, etc, you must get it right the first time and you must be precise. Like you said yourself, there is a huge amount of difference between the two protocols RIP and RIP2.

When you are talking to someone who does not know the differences between them, using a statement like RIP does not carry subnet information is misleading and can cause that person some heartache later on because they think ALL RIP behaves this way. Or they just do not know there are two version of RIP.

yes it's spliting hairs, but in the real world, spliting hairs can be the difference between keep a job and losing it.

MikeS
Find me at

http://www.packetattack.com

"The trouble with giving up civil rights is that you never get them back"

 

[CCIEWANNABE]

Directed to wybnormal
Link:

http://www.isi.edu/in-notes/rfc1058.txt

"The RIP protocol makes no formal distinction between networks and hosts"
RFC supports my argument RFC1058.
Again RIP only summarizes at network boundaries. When RIP sends the update, it checks to see whether the network being advertised has the same network mask. If the advertised network has a different mask, RIP does not advertise the network.

Directed to: wannaciscobe

Additional troubleshooting ideas that can help eliminate your problem? May or may not resolve the issue.

Is Rip Enabled on all the interfaces? #show ip route
Are the sending and receiving interfaces up/up? #show IP protocol ......look for correct gateway information.
Is the distributed-list in blocking the routes. Make sure the distribute-list in permits rip updates.
Are you using Access lists to block RIP broadcasts? if using let me know
Are the Rip versions compatible? Default value is Rip1 Check Line under Router RIP Rip 1 can only understand version one packets.
Is there a discontigous subnet? When networks are separated they become discontigous. Use debug ip rip. Verify correct network statements.
Are the RIP updates coming from valid sources.
Is the network metrics listed more then 15 hops away?

Just check if rip routes are in the routing table and you have valid network statements?
Route once; switch many

 

[wybnormal]

::sigh::

Directed to CCIEWANNABE

If you would take the time to read the posts carefully...

From you:"Again RIP only summarizes at network boundaries. When RIP sends the update, it checks to see whether the network being advertised has the same network mask"

What I had said in the beginning was "RIP does not carry a mask per say, it DOES assume a default mask.. ie.. classFULL mask."

So from the beginning, we were in agreement. RIP version 1 does not carry subnet info, it assumes a classfull mask.

RIP 1 and 2 are not two different protocols, they are at the core, the same protocol using the same calculations for deciding hwo to route. Take one protocol, keep the basic concept of how it works and enhance it. In my mind, two different protocols would be something like OSPF vs. BGP. Completely different way of routing.

THis part of the dicussion could fall under the tomato argument.. you say it one way, I say it another way and yet both are correct.

Now.. my point to all this wasted bandwidth was that a GLOBAL answer of RIP DOES NOT CARRY SUBNETS is badly worded. RIP version 2 Does in fact carry subnet info.

http://www.faqs.org/rfcs/rfc1721.html

::snip::
"While RIP-2 shares the same basic algorithms as RIP-1, it supports several new features. They are: external route tags, subnet masks, next hop addresses, and authentication"
::snip::

When writing an answer, you should and in my mind, must specify WHICH RIP you are discussing. IE..

RIP = RIP 1 or do you mean RIP = RIP2

RIP 1 does not carry subnets... not just RIP does not carry subnets. It really does make a difference

Like I said before, asssume the person does NOT know the differences when writing. Make sure it's clear what version of what you are discussing, whether it be BGP, RIP or an IOS level.

We are not as far apart as you seem to think.

Enough wasting of bandwidth.

We return to our regularly scheduled programming.

MikeS
Find me at

http://www.packetattack.com

"The trouble with giving up civil rights is that you never get them back"

 

[CCIEWANNABE]

"quote wybnormal If you would take the time to read the posts carefully..."did you read his post carefully he says RIP v1.[/red]
Nothing about RIPv2. No were in any post did we discuss RIPv2 in till you interjected that I was discussing RIP (Short for Routing Information Protocol) as a blanket statement and was incorrectly stating the properties of RIP. All my responses referrers to RIP not RIPv2
"Quote wannaciscobe I'm using rip v1 " Any Test a user takes will state ether RIP or RIP version 2. Nowhere have I seen a question based on the term Rip version one. RIP is RIP and RIPv2 is RIP version 2
That’s why we have different RFC for both protocols. RFC 1058, and RFC 1723; 2453

Link:

http://www.isi.edu/in-notes/rfc1058.txt

http://www.isi.edu/in-notes/rfc1723.txt

http://www.isi.edu/in-notes/rfc2453.txt

Take notice the RFC1058 does not say AKA: Rip version 1 only RIP.
Yet RIP Version 2is stated as RIP Version 2. I suggest you read the post carefully and backup your statements with proof such as I have. Also since you want to split hairs you left out the most important feature of RIP version 2, which supports VLSM and discontiguous networks. Now if you want I can post you a link to the frame format of RIP and RIP-2.

RIP has no packet format for subnet mask within its packet. Thanks for the stimulating debate in any case. All this should be in a new FAQ and has gone off topic?
But since I try to be a perfectionist by nature I have attached additional support links.
[URL unfurl="true"]http://www.cisco.com/univercd/illus/c/01/ct844701.gif[/URL] ;
[URL unfurl="true"]http://www.cisco.com/univercd/illus/c/02/ct844702.gif[/URL] I rest my case.



Route once; switch many

 

[Speaker]

Well I think the conversation is getting a bit acrimonious.

I understand from a purely one's and zero's perspective, that RIP refers to v1, and v2 will always be called RIPv2. So CCIEWANNABE's post was 100% correct.

I also understand that wybnormal was trying to clear up something that was *related* to the discussion that could cause misunderstandings later--especially if beginners got it stuck in their head that RIP (in any form) never carries the subnet mask.

As a relative beginner to the intricacies of routing protocols, I appreciate the input from both posters.

Let's not let it descend into a pissing contest, please... I still need help with mirroring to multiple ports, and I don't want any of the resident experts getting pissed right now.

 

[wannaciscobe]

Speaker...
It's obvious that both of these guys are very very good at what they do....otherwise we wouldn't be asking them any of these questions!!
I appreciate all their help and hope they don't kill each other by the time my next question rolls around!!!!!

Bob

 

[CCIEWANNABE]

I have found that when networks use RIP { AKA RIP version 1 } that they dont realize that RIP does not support Discontiguous Networks. Meaning: "Major Networks sepreated by a major network". Rip Summarixes the address.
I can start with the suggestion that you configure static routes on the routers in question that points toward the specific subnets you have created. If your confused do a search on troubleshooting Autosummarization You state that all serial interfaces respond yet the Ethernet interfaces do no respond? Is this correct? Also
Verify correct network statements on the interfaces?

In example:

Router1(config)#ip route [Subnet value of Ethernet interface address][Mask Value] [Router 2 Serial IP address)
Router2(config)#ip route [Subnet value of ethernet interface address][Mask Value] [Router 1 Serial IP address)
and so on if you have more then two routers.

Route once; switch many

 

[wybnormal]

Pissing contest? hardly... you want to see a *real* pissing contest, wander over one of the cisco or MS newsgroups.. it can be pretty eye opening just how much this stuff can get out of hand.

Anyways...

So.. the short version is that each of the routers can ping each other's interfaces?

R1---R2---R3

R1 can ping R3, R2 can ping either R1/E0 or R3/EO and R3 can ping all the way back? But the hosts can NOT ping through? or ping even the local serial interface IP address?

Are all subnets classful? ie.. 192.168.5.1 255.255.255.0 (normal class C subnet) ? or 10.1.1.1 255.0.0.0?

Each segment has it's own subnet?

Say we use 192.168.0.0

Host1 to R1/E0 192.168.5.x
R1/S0 to R2/S0 192.168.10.x
R2/S1 to R3/S0 192.168.15.x
R3/E0 to host2 192.168.20.x

Something like this?

Rip is enabled yes? each subnet on each device is named in the network statement?

R1 would have 192.168.5.x and 192.168.10.x listed and for good practice at network design, use passive-interface on the E0 port. The upshot here is that you are telling RIP to advertise both interfaces network subnets.

When you do a show ip route, you should see both local interfaces as C (connected) and then whatever the router has learned as R(rip)

You can run a debug ip rip and see the actual events for rip as they transpire. It's a great way to verify things are working exactly as you think they should be.

Speaking of troubleshooting, a very good book to get is called *Cisco Router Troubleshooting Handbook* by Peter Rybaczyk. It's a very handy ready reference type of book.

The host default gateways are point to their respective routers R1 and R3 yes?

I'm sure if I missed something, it will be pointed out ;-)

Let us know what the answers are.. and dont worry too much about couple of cranky engineers with too much caffine in their systems

MikeS
Find me at

http://www.packetattack.com

"The trouble with giving up civil rights is that you never get them back"

 

[wannaciscobe]

MikeS,
Thanks for the info...I'm going to double check what I've got going on....after a couple of hrs...I'm a little blurry and make mistakes....easy ones.....

I will give the full details soon...it's probably a mis-config on my part....
I think I'm going to start with static routes just to prove to my self that it's all set up correctly.

And BTW...."passive-interface" on the EO? so they don't fwd the routes to the client machines???? (just guessing)

bob

bob

 

[wybnormal]

Something like that.. passive=interface is a way to keep a router interface from singing it's heart out about all the routes it knows.. it still listens tho. The idea is to keep routing protocols off segments that do not need it.. ie.. passive the ethernet side to avoid putting RIP onto the ethernet segment.(unless it's needed) Some of the configs in the Academny series use this as a *best practice* However, there is a gotcha with it...

"The passive interface feature behaves differently with different protocols. On most protocols, passive interface stops the router from sending updates to a particular neighbor, but continues to listen and use routing updates from that neighbor. However, on EIGRP, passive interface causes the router to stop sending and receiving hello packets. "

http://www.cisco.com/warp/public/103/16.html

Another gotcha to remember is the default of "no directed broadcast" on the interfaces. I got bit by an upgrade from 11.2 to 12x and this nifty default broke a DHCP segment. I had not noticed the line being inserted into the config and it wasnt till people's leases timed out a day later

MikeS
Find me at

http://www.packetattack.com

"The trouble with giving up civil rights is that you never get them back"

 

[wannaciscobe]

Thanks for the info.... I wish I could just magically know this stuff instantly...lol....but I'm enjoying the trip....
bob

 

[jjjthird]

WOWZA, I love this !! Teach me more Teach me more,lolol.
Great job

 

[wannaciscobe]

FYI to all who helped.....

I went back and config'd static routes and all is well ping-wise...next...onto RIPV2 config...
Thanks again for all your input...

bob

 

[CCIEWANNABE]

RIPV2 config is the major leagues. Lots of new issues. Route once; switch many