Intervlan routing and NAT

zaidiatifs · ‎05-30-2013

hi i am trying to have the vlans communicate with each other using router on a stick , i have attached the packet tracer file for the same .

i have configured subinterfaces on the router and still the vlans are not able to communicate with each other , please advise and help me .

thanks .

Bilal Nawaz · ‎05-31-2013

Hello Atif,

There are a couple of things that were missing and perhaps configured wrong... I'll try to explain these to help you understand what is required. You can find attached my version with complete connectivity.

The gateway on the laptop in vlan 10 was wrong, so i corrected this.

You had VTP set up which is good, however the vlans were not created on the VTP Server. So I created the vlans on the VTP server and subsequently they got created on the clients.

Then I made sure that I put the Laptops in the correct vlan as access ports. You just had 'switchport mode access' - this by default puts everything in vlan 1.

I also made sure that the trunks were functional between the switches and were carying the correct vlans.

'switchport mode trunk'

After I had done these steps, I verified that there was LAN connectivity and also intervlan routing.

Next is to see what the enterprise core router is doing. It does not have any routes, nor does it have a frame-relay encapsulation set on the outgoing interface to the internet, we need to set a default route to the internet too right?

First we get the frame-relay working

Core router

interface Serial3/0

ip address 65.10.1.1 255.255.255.252

encapsulation frame-relay

Remote router

interface Serial2/0

ip address 65.10.1.2 255.255.255.252

encapsulation frame-relay

I had to create a DLCI on the service provider cloud to make the frame-relay mapping to work. I used 101 mapping for both of them.

However the enterprise core does not have routes to get back to vlan 10,20,30,40,50 and 60.

I see that you have tried to enable RIP v2 with the Enterprise core router, and i have completed this and the routes are advertised, I also generated the default route from the Core and advertised it to Router 1 and the branch router.

i did this with the 'default-information originate' command.

Core router

router rip

version 2

network 10.0.0.0

network 65.0.0.0

default-information originate

no auto-summary

Now the core has routes to get to the intervlan subnets and also 172 network.

core#show ip route

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

10.0.0.0/30 is subnetted, 1 subnets

C 10.10.1.32 is directly connected, Serial2/0

20.0.0.0/24 is subnetted, 1 subnets

R 20.10.1.0 [120/1] via 10.10.1.33, 00:00:27, Serial2/0

30.0.0.0/24 is subnetted, 1 subnets

R 30.10.1.0 [120/1] via 10.10.1.33, 00:00:27, Serial2/0

40.0.0.0/24 is subnetted, 1 subnets

R 40.10.1.0 [120/1] via 10.10.1.33, 00:00:27, Serial2/0

50.0.0.0/24 is subnetted, 1 subnets

R 50.10.1.0 [120/1] via 10.10.1.33, 00:00:27, Serial2/0

60.0.0.0/24 is subnetted, 1 subnets

R 60.10.1.0 [120/1] via 10.10.1.33, 00:00:27, Serial2/0

65.0.0.0/30 is subnetted, 1 subnets

C 65.10.1.0 is directly connected, Serial3/0

100.0.0.0/24 is subnetted, 1 subnets

R 100.10.1.0 [120/1] via 10.10.1.33, 00:00:27, Serial2/0

172.16.0.0/28 is subnetted, 1 subnets

R 172.16.1.0 [120/1] via 65.10.1.2, 00:00:04, Serial3/0

core#

Note that there was no need for NAT.

Hope this helps, please ask if you have any questions.

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paul driver · ‎05-31-2013

Hello All

Just like to mention as for the serial interfaces not having Fame relay encapsulation, just because it not showing the encapsulation doesn't mean it not using any, like HDLC.

res

Paul

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Bilal Nawaz · ‎05-31-2013

Hello Paul,

I would disagree in that (we leave it as default - no encap specified) But you are correct - the default here is HDLC, in this case you had to enable the encapsulation type for the interface to transition to an 'UP' state and was infact necessary - it may be using HDLC by default but in this case it wouldn't work with this default.

In PT the cloud is a cloud with FR capabilities - this is the only thing stated here. So one should assume the encapsulation to be frame-relay.

core(config)#int s3/0

core(config-if)#no encapsulation

%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial3/0, changed state to down

core(config-if)#

core(config-if)#encapsulation frame-relay

core(config-if)#

%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial3/0, changed state to up

core(config-if)#

With encap

core#show int se3/0

Serial3/0 is up, line protocol is up (connected)

Hardware is HD64570

Internet address is 65.10.1.1/30

MTU 1500 bytes, BW 128 Kbit, DLY 20000 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation Frame Relay, loopback not set, keepalive set (10 sec)

LMI enq sent 2, LMI stat recvd 2, LMI upd recvd 0, DTE LMI up

LMI enq recvd 0, LMI stat sent 0, LMI upd sent 0

LMI DLCI 1023 LMI type is CISCO frame relay DTE

Broadcast queue 0/64, broadcasts sent/dropped 0/0, interface broadcasts 0

Last input never, output never, output hang never

Last clearing of "show interface" counters never

Input queue: 0/75/0 (size/max/drops); Total output drops: 0

Queueing strategy: weighted fair

Output queue: 0/1000/64/0 (size/max total/threshold/drops)

Conversations 0/0/256 (active/max active/max total)

Reserved Conversations 0/0 (allocated/max allocated)

Available Bandwidth 96 kilobits/sec

5 minute input rate 6 bits/sec, 0 packets/sec

5 minute output rate 25 bits/sec, 0 packets/sec

75 packets input, 3900 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

74 packets output, 14208 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

0 carrier transitions

DCD=up DSR=up DTR=up RTS=up CTS=up

With default hdlc

core#show int se3/0

Serial3/0 is up, line protocol is down (disabled)

Hardware is HD64570

Internet address is 65.10.1.1/30

MTU 1500 bytes, BW 128 Kbit, DLY 20000 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation HDLC, loopback not set, keepalive set (10 sec)

Last input never, output never, output hang never

Last clearing of "show interface" counters never

Input queue: 0/75/0 (size/max/drops); Total output drops: 0

Queueing strategy: weighted fair

Output queue: 0/1000/64/0 (size/max total/threshold/drops)

Conversations 0/0/256 (active/max active/max total)

Reserved Conversations 0/0 (allocated/max allocated)

Available Bandwidth 96 kilobits/sec

5 minute input rate 11 bits/sec, 0 packets/sec

5 minute output rate 35 bits/sec, 0 packets/sec

75 packets input, 3900 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

74 packets output, 14208 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

0 carrier transitions

DCD=up DSR=up DTR=up RTS=up CTS=up

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paul driver · ‎05-31-2013

Hello bilal
i am not saying his issue doesnt require FR
i cannot see the packet tracer so cannot comment on that - however hdlc is a viable encasulation and if this is a back to back connection then FR isnt applicable

All that is requied is Just to disable keepalives and clock rate in the dce

Res
Paul

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Bilal Nawaz · ‎05-31-2013

Okay, i see what you mean now

Are there any pro's or con's with either, just out of interest?

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cadet alain · ‎05-31-2013

Hi Bilal,

either what ?

Regards

Alain

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Bilal Nawaz · ‎05-31-2013

Hello Alain,

I mean between HDLC / or default encapsulations vs Frame Relay in this type of legacy 'cloud environment'

Are there any proper benefits - like performance etc...

In Atif's case he was using a frame-relay cloud so encapsulation was necessary,

For his other links, default was used with no encapsulation set. Just to paint the picture here's a screenshot

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paul driver · ‎05-31-2013

Hello

One is using the Fr cloud the other isn't

no lmis or static mappings!

res

paul

Please rate and mark as an accepted solution if you have found any of the information provided useful.
This then could assist others on these forums to find a valuable answer and broadens the community’s global network.

Kind Regards
Paul