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Cisco 3550 and InterVlan Routing Help

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lmcdd

Technical User
Apr 28, 2004
5
US
InterVlan newbie here with a problem and can't seem to find the answer in the Cisco documentation.

Recently inherited control of an undocumented network consisting of one building--bldg2--with five Cisco 3524 switches and one Cisco 3550 switch with the Layer2/Layer3 IOS image Version 12.1(14)EA1a. All six are daisychained together via GBIC configured as 802.1Q trunks. We have a 3620 hung off one of the 3524s. The 3620 in bldg1 connects to a 3620 in bldg1 via a RF bridge. There's a Cisco 6509 bldg1 with 2 MSFC modules.

Everything in both buildings is using the default VLAN1 on 172.16.0.0/21. I've been tasked with changing that. To start, in bldg2, we have about 20 macs that I want to move to their own Vlan/subnet and connect to the access ports on the 3550. I created a new vlan (48) on the 3550 which is running in VTP server mode with all other switches in client mode. The Vlan replicates to the other switches in bldg2 fine. I assigned an address of 172.16.48.1/21 to the SVI for the Vlan to use as the new default gateway for the macs.

I need the macs to be able to talk to other resources on the network outside their Vlan so I need to use InterVlan routing. According to the Cisco docs, the next step to do this is to turn on routing in the 3550 by issuing the (config)#ip routing command. Once I do that, I can do a #show ip route and see the IPs for Vlan1 and Vlan48 as physically connected routes but within about 10 minutes, I lose connectivity to the 3550 from bldg1. The 3550 can't be reached from bldg1 via ping though bldg2 is fine and there's no loss of user connectivity. As soon as I turn routing off in the 3550, I can connect to the 3550 again from bldg1.

I know I'm just making a config mistake somewhere. Anyone have any suggestions?

Thanks
 
How about posting your Cat3550 config?

Peter Mesjar
CCNP, A+ certified
pmesjar@centrum.sk

"The only true wisdom is in knowing you know nothing.
 
Current configuration : 3323 bytes
!
! Last configuration change at 18:49:27 UTC Wed Apr 28 2004
! NVRAM config last updated at 17:24:45 UTC Tue Apr 27 2004
!
version 12.1
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Sw3550f
!
enable secret 5 $1$3bLq$wx/w.TiT4TkDdPCQtRxs4.
!
ip subnet-zero
!
!
spanning-tree mode pvst
spanning-tree extend system-id
!
!
!
interface FastEthernet0/1
switchport mode dynamic desirable
spanning-tree portfast
!
interface FastEthernet0/2
switchport mode dynamic desirable
!
interface FastEthernet0/3
switchport mode dynamic desirable
!
interface FastEthernet0/4
switchport mode dynamic desirable
!
interface FastEthernet0/5
switchport mode dynamic desirable
!
interface FastEthernet0/6
switchport mode dynamic desirable
!
interface FastEthernet0/7
switchport mode dynamic desirable
!
interface FastEthernet0/8
switchport mode dynamic desirable
!
interface FastEthernet0/9
switchport mode dynamic desirable
!
interface FastEthernet0/10
switchport mode dynamic desirable
!
interface FastEthernet0/11
switchport mode dynamic desirable
!
interface FastEthernet0/12
switchport mode dynamic desirable
!
interface FastEthernet0/13
switchport mode dynamic desirable
!
interface FastEthernet0/14
switchport mode dynamic desirable
!
interface FastEthernet0/15
switchport mode dynamic desirable
!
interface FastEthernet0/16
switchport mode dynamic desirable
!
interface FastEthernet0/17
switchport mode dynamic desirable
!
interface FastEthernet0/18
switchport mode dynamic desirable
!
interface FastEthernet0/19
switchport mode dynamic desirable
!
interface FastEthernet0/20
switchport mode dynamic desirable
!
interface FastEthernet0/21
switchport mode dynamic desirable
!
interface FastEthernet0/22
switchport mode dynamic desirable
!
interface FastEthernet0/23
switchport mode dynamic desirable
!
interface FastEthernet0/24
switchport mode dynamic desirable
!
interface GigabitEthernet0/1
switchport trunk encapsulation dot1q
switchport mode trunk
!
interface GigabitEthernet0/2
switchport mode dynamic desirable
!
interface Vlan1
ip address 172.16.46.6 255.255.248.0
no ip route-cache
no ip mroute-cache
!
interface Vlan48
ip address 172.16.48.1 255.255.248.0
no ip route-cache
no ip mroute-cache
!
interface Vlan77
no ip address
no ip route-cache
no ip mroute-cache
!
ip classless
ip http server
 
What port connects to your 3640? Also, what IP address is the 3640.
 
Can you explain in detail how the 3640 connects up to your 3550?

I.E.

How is the 3524 connected?
What VLAN is the 3640 on?
What IP address is the 3640 using?
What is the IP subnet of the bldg1?
 
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