Layer 3 routing on LAN

RAJ VIRDI · ‎03-10-2011

We have a Cisco 3750 stack set up as layer 3 with mulitple VLANs and EIGRP and ip routing. Also connected to this stack are a SAN as well as downstream 2960s. The 2960 are configured with the DG as the 3750 as are all devices and hosts on the network. The 3750s connect to a WAN router. When accessing resources across the LAN, for example the SAN or local proxy server, all traffic is traversing the WAN router. I would expect all local traffic to be routed via the layer 3 3750 and not the WAN router? We have Riverbeds between the LAN and the WAN and the netflow from these show LAN to LAN traffic traversing this point. Any pointers in how to troublseshoot? Have tried the traceroutes and extended ping Record commnads from the switch which show just the hops as expected (no WAN router)

andrehbosch · ‎03-10-2011

Hi there

Please paste your configs for switch and Router, and a Diagram.

Regards

RAJ VIRDI · ‎03-10-2011

Here's part of the config detailing the networks, VLANs etc...Thanks for taking a look

interface Vlan1
description LAN Subnet
ip address 172.16.27.240 255.255.255.0
ip helper-address 172.18.202.3
no ip mroute-cache
!
interface Vlan2
description Wired DHCP Users
ip address 172.16.28.240 255.255.255.0
!
interface Vlan3
description Wireless Management
ip address 172.16.101.254 255.255.255.224
!
interface Vlan5
description Parker Staff Wireless
ip address 172.16.101.126 255.255.255.128
!
interface Vlan7
description Guest Wireless Users
ip address 172.16.101.190 255.255.255.192
!
interface Vlan9
description Wireless Scanners and Printers
ip address 172.16.101.222 255.255.255.224
!
interface Vlan100
description SAN Mgnt & iSCSI
ip address 172.16.100.254 255.255.255.0
!
router eigrp 1
passive-interface Vlan2
network 172.16.27.0 0.0.0.255
network 172.16.28.0 0.0.0.255
network 172.16.100.0 0.0.0.255
network 172.16.101.0 0.0.0.255
no auto-summary
!
ip local policy route-map GUEST_WIRELESS_TRAFFIC
ip classless
ip route 0.0.0.0 0.0.0.0 172.16.27.254 (WAN Router)
ip route 192.0.2.1 255.255.255.255 Null0
ip http server
ip http secure-server

Chris Burwell · ‎03-10-2011

You initial post says "When accessing resources across the WAN". Are you

accessing devices say in VLAN100 from VLAN2 or from a remote subnet that does not exsist on

the 3750?

What traffic is the Riverbed appliance showing?

Packet captures are a good way to see what is happening.

RAJ VIRDI · ‎03-11-2011

My apologies, this should read LAN...basically when accessing LAN to LAN traffic between local hosts, the traffic is seen on the Riverbeds.

lucentmoon · ‎03-11-2011

Could you post a sh ip route for the 3750 please? Have you noticed traffic from all vlans traversing the link to the Router or just specific vlans/subnets?