Cat3560 Multilayer Switch inter vlan routing help!

thedrama · December 2012

Why doesn't this topology work? i can not seem to find it.

I assigned IP addresses to each SVI on the MLS. Typed "ip routing". i wasnt sure about i have to config. a routing protocol after that,though i did. typed each network on the MLS. Set the interfaces trunk between each switch as well as the one between MLS. Set access ports for computers. Assigned them into different subnets.

But, still doesn't work.

help me pls.

here is the topology below

lalala.pkt - Speedy Share - upload your files here

mattau · December 2012

is it possible to show a screen shot attached to this forum?

id go through troubleshooting steps from a pc.

- can you ping the default gateway? SVI in the same vlan as pc
- if so can you ping the other SVI on the same switch in a different vlan?
- if you cant ping DG then you can either start at PC then access then go up to MLS
- is access switch access port connected to pc in correct vlan? is the phyiscal link status UP/UP ?
- does host have an ip. is ip in the correct subnet that SVI is on.
- check ip routing on MLS
- check SVI's in correct vlan, subnet mask is correct.
- is SVI UP/UP ? vlan must be in vlan database and active on switch, eg allowed on trunks
- interswitch connectivity. does trunk allow vlan over it? show vlan brief
- show spanning-tree (are the ports you expect to be FWD are in FWD, not err disable block or anything they shouldnt be.

thedrama · December 2012

mattau wrote: »

is it possible to show a screen shot attached to this forum?

id go through troubleshooting steps from a pc.

- can you ping the default gateway? SVI in the same vlan as pc
- if so can you ping the other SVI on the same switch in a different vlan?
- if you cant ping DG then you can either start at PC then access then go up to MLS
- is access switch access port connected to pc in correct vlan? is the phyiscal link status UP/UP ?
- does host have an ip. is ip in the correct subnet that SVI is on.
- check ip routing on MLS
- check SVI's in correct vlan, subnet mask is correct.
- is SVI UP/UP ? vlan must be in vlan database and active on switch, eg allowed on trunks
- interswitch connectivity. does trunk allow vlan over it? show vlan brief
- show spanning-tree (are the ports you expect to be FWD are in FWD, not err disable block or anything they shouldnt be.

thats weird. i started from zero and put a router instead of MLS. It didn't work either. When my friend told me that i have to create other vlans on each l2 switch, it worked.

But still can't realise why it didn't work before. why do i have to create other vlans? (for ex. computers on vlan 10,20
are connected to regarding switch but it failed without introducing vlan 30,40 and 50 too)

Furthermore,

Later, i replaced the router with MLS.

- MLS config. using SVI -

int fa 0/1
switchport trunk encapsulation dot1q
switchport mode trunk

int vlan 10
ip address 192.168.10.252 255.255.255.0
no sh

int vlan 20
ip address 192.168.20.252 255.255.0

ip routing

mattau · December 2012

im not sure how you mean?

All switches need to know about the same vlans, other wise spanning tree cannot create an instance for that vlan thus the vlan wont be allowed to be forwarded over a trunk.

Maybe thats why you had mixed results, vlans weren't known to everyone and there were issues sending that vlan over the trunk due to STP not being active and forwarding for that vlan.

By default as long as you have the vlan active on the switch then all vlans are allowed over a trunk.

Cat3560 Multilayer Switch inter vlan routing help!

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