cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
2014
Views
0
Helpful
53
Replies

CISCO 871W cannot ping external router interface

jprophet64
Level 1
Level 1

Good morning everyone,

I hope someone here could assist me with the situation I am facing, I am a network administrator who has been assigned the task of adding a secondary router to a redundant backup third party provided internet circuit. This router will serve two-fold firstly it will serve out dhcp addresses through a dhcp pool and secondly it will accomodate 2 Unifi AP access points. I'll show my config below but the end result is I cannot ping the outside router interface that the ISP has provided which ultimately should allow me to get on the internet.  My config is below:

 

CLTCHIEF2#show run
Building configuration...

Current configuration : 1934 bytes
!
! Last configuration change at 17:52:47 UTC Sun Mar 3 2002
!
version 15.1
no service pad
service timestamps debug datetime msec
service timestamps log datetime msec
service password-encryption
!
hostname CLTCHIEF2
!
boot-start-marker
boot-end-marker
!
enable secret 5 $1$fMm.$fVzzs3q6pnSM6avr03Nho1
enable password 7 12211D0E081115
!
no aaa new-model
!
!
dot11 syslog
ip source-route
ip dhcp excluded-address 172.16.102.1 172.16.102.99
ip dhcp excluded-address 172.16.102.151 172.16.102.254
!
ip dhcp pool CLT2WIRELESS
   network 172.16.102.0 255.255.255.0
   default-router 172.16.102.1
   domain-name INTERNAL.COM
   lease 7
!
!
ip cef
no ip domain lookup
!
!
!
!
!
!
!
!
!
!
bridge irb
!
!
!
interface FastEthernet0
!
interface FastEthernet1
 shutdown
!
interface FastEthernet2
!
interface FastEthernet3
!
interface FastEthernet4
 description WAN INTERFACE
 ip address 50.58.80.82 255.255.255.252
 ip nat outside
 ip virtual-reassembly
 duplex auto
 speed auto
!
interface Dot11Radio0
 no ip address
 shutdown
 speed basic-1.0 basic-2.0 basic-5.5 6.0 9.0 basic-11.0 12.0 18.0 24.0 36.0 48.0
 54.0
 station-role root
!
interface Vlan1
 description VLAN WIRED AND WIRELESS
 no ip address
 no ip redirects
 bridge-group 1
!
interface BVI1
 description VIRTUAL BONDED INTERFACE
 ip address 172.16.102.2 255.255.255.0
 no ip redirects
 no ip unreachables
 ip nat inside
 ip virtual-reassembly max-reassemblies 1024
 ip tcp adjust-mss 1360
 load-interval 30
!
ip forward-protocol nd
no ip http server
no ip http secure-server
!
ip nat inside source list 150 interface FastEthernet4 overload
ip route 0.0.0.0 0.0.0.0 172.16.102.1
ip route 0.0.0.0 0.0.0.0 50.58.80.81
!
access-list 150 remark NAT TRANSLATIONS
access-list 150 permit ip 172.16.102.0 0.0.0.255 any
!
!
!
snmp-server community public RO
!
control-plane
!
!
line con 0
 no modem enable
line aux 0
line vty 0 4
 password 7 07173955541300
 login
 transport input all
!
end

 

 

Does this config look right?

 

Thank-you.

 

53 Replies 53

Yes,

I checked out the isp router's interface and saw that there was no light activity so I kust unplugged it and plugged it back in and voila! So it appears that the customer g0/1 went into a sleep mode or something.

I intend on connecting a 3548P switch to one the fa0-3 ports, so within the router dont i just need to under the interface add the line "switchport mode access" to make it work.

 

John

 

I do not have a lot of experience with the 871 router. But my impression is that fa0-3 are effectively switch ports. While it would not hurt to configure them with switchport mode access I believe that it is not necessary.

 

HTH

 

Rick

HTH

Rick

I intend on connecting a 3548P switch to one the fa0-3 ports, so within the router dont i just need to under the interface add the line "switchport mode access" to make it work.

I don't think you need to add anything as they can only be L2 ports (f4 is the only L3 port) and you are using the default vlan.

Jon

Jon is right this is a significant issue and is very surprising since there has been an arp entry for .81 previous times when we looked at arp.

 

If arp can not resolve the address for .81 then certainly we will have no connectivity.

 

HTH

 

Rick

HTH

Rick

The mention of hyperterm makes me wonder if he is connected from his laptop to the router console and is doing the ping from the router console, which should work just fine.

 

The show arp does show a device at 172.16.102.100 which is the first available address in the DHCP pool and I wonder if that is his laptop. Perhaps the original poster can clarify how the ping is being done and what is in the output of ipconfig from his laptop.

 

HTH

 

Rick

HTH

Rick

Yes that is correct I am connected to the router console using a laptop remotely, that laptop is using wireless on a different subnet so that I can get to the hyperterminal session.

My remote laptop has grabbed 172.16.102.100 as intended from the pool but my concern is it is not showing a default gateway. Without this I will not be able to get to the internet from the inside? 

Rick

The mention of hyperterm makes me wonder if he is connected from his laptop to the router console and is doing the ping from the router console, which should work just fine.

Good point, I expect that explains the ping.

Any ideas about the DHCP default gateway ?

Jon

Jon

 

I agree that it is getting a bit confusing. The config looks pretty good to me. And the output of show arp leads me to believe that there should be IP connectivity. We do need the original poster to clarify what is working and what is not working. And posting the output of ipconfig would be helpful also.

 

HTH

 

Rick

HTH

Rick

Thanks for the updated config. If you do not plan to use the wireless then removing the bridging and the BVI interface makes sense. But in that case I would think that you would want to put an IP address for vlan 1. As it stands now the only interface with an IP address is the WAN interface. So effectively you have no LAN at this point.

 

With this changed config can the router ping the external router? If not then please post outputs from show ip arp and from show ip interface brief.

 

HTH

 

Rick

HTH

Rick
Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community: