cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
Announcements

Cisco Community Designated VIP Class of 2020

474
Views
10
Helpful
8
Replies
Highlighted
Beginner

VLAN trunking issue

Hi There,

 

We have few VLANs span across 2 cisco 3750 switches.  Switch1 and Switch2. 

 

Configuration for both the switches is attached.  VLANs across switches is accessible with the following issues.

 

1. The switch 2 can not ping VLAN Interface IP of switch 1 and viceversa. 

2. If any VLAN defined on switch2 , it is not getting accessible from other VLANs. but switch1 VLANs can be accessed .[ie vlans 22,50,60 and 80 can be accessed across switches but vlan33 cant be accessed]

 

Thanks 

 

Sandip

Everyone's tags (3)
2 ACCEPTED SOLUTIONS

Accepted Solutions
VIP Mentor

Re: VLAN trunking issue

Hello

sw1

doesn’t have any vlan33 ip addressing 

also enable ip routing 

 

 

sw2 

disable ip routing and give it an default gateway of Sw1 vlan33 ip address 



kind regards
Paul

Please rate and mark posts accordingly if you have found any of the information provided useful.
It will hopefully assist others with similar issues in the future

View solution in original post

VIP Expert

Re: VLAN trunking issue

However, here the question is why we have to give Gateway address for VLAN33 PCs as Sw1 VLAN33 Ip address ?  This way it has to traverse to the Sw1 always if need to communicate with other VLAN.

That is correct. In this case, sw2 is simply a layer-2 device with one ip for management only and sw1 is doing the routing between vlans.  If for redundancy you want both sw1 and sw2 to do the routing for you, then you have to make sure there is trunk link between the 2 switches and then run hsrp or vrrp on both switches. That way switch is the active router and the other switch is on standby. 

-Why VLANs configured on Sw2  in the same way as Sw1 doesn`t work and we need to direct default route to Sw1 to make it working ?

Again sw2 is just layer-2 and that one IP you gave it is for managing the switch itself but all the inter-vlan routing is done on sw1. Also, on sw2, the reason that you need to have a default route to sw1 is that other subnets can reach sw2. Again this IP on sw2 is just for management, so you can telnet or ssh to the switch.

HTH

View solution in original post

8 REPLIES 8
VIP Expert

Re: VLAN trunking issue

Hi,

switch 2 does not have any default route or default gateway defined.

ip route 0.0.0.0 0.0.0.0 10.10.30.x where x is the gatway for this subnet

 HTH

Beginner

Re: VLAN trunking issue

Thanks for the suggestion.  However, even after adding default route (and related VLAN for the default route) it doesn`t work.

updated config for switch2 and basic diagram of connection attached.

VIP Advocate

Re: VLAN trunking issue

HI,

Both switches having "IP Routing" command enabled. So you must have disabled the "IP Routing" from the 2nd switch (access switch). It will start working. 

Command:

No ip routing

Regards,
Deepak Kumar,
Don't forget to vote and accept the solution If this comment will make help you!
Beginner

Re: VLAN trunking issue

tried that but it is not having any effect.
VIP Advisor

Re: VLAN trunking issue

Can you able to ping from 1.99 to 10.10.30.254  ( if this working, then this could be an issue with PC have FW ? building, what OS is this PC ?)

 

interface Vlan33
ip address 10.10.30.254 255.255.255.0

 

can you post from bot the switches show ip route

BB
*** Rate All Helpful Responses ***
VIP Mentor

Re: VLAN trunking issue

Hello

sw1

doesn’t have any vlan33 ip addressing 

also enable ip routing 

 

 

sw2 

disable ip routing and give it an default gateway of Sw1 vlan33 ip address 



kind regards
Paul

Please rate and mark posts accordingly if you have found any of the information provided useful.
It will hopefully assist others with similar issues in the future

View solution in original post

Beginner

Re: VLAN trunking issue

With below config it works : ie each vlan PC communicate with different VLAN PCs. and switches can ping VLAN Interface IPs.

 

- Sw 1 gave VLAN33 ip address (10.10.30.1)

 

- Sw2 disable IP routing and set VLAN33 ip address of sw1 (10.10.30.1) as default gateway.

Configured 10.10.30.x LAN default gateway as sw1 VLAN33 ip address (10.10.30.1)

******

However, here the question is why we have to give Gateway address for VLAN33 PCs as Sw1 VLAN33 Ip address ?  This way it has to traverse to the Sw1 always if need to communicate with other VLAN.

-Why VLANs configured on Sw2  in the same way as Sw1 doesn`t work and we need to direct default route to Sw1 to make it working ?

 

 

VIP Expert

Re: VLAN trunking issue

However, here the question is why we have to give Gateway address for VLAN33 PCs as Sw1 VLAN33 Ip address ?  This way it has to traverse to the Sw1 always if need to communicate with other VLAN.

That is correct. In this case, sw2 is simply a layer-2 device with one ip for management only and sw1 is doing the routing between vlans.  If for redundancy you want both sw1 and sw2 to do the routing for you, then you have to make sure there is trunk link between the 2 switches and then run hsrp or vrrp on both switches. That way switch is the active router and the other switch is on standby. 

-Why VLANs configured on Sw2  in the same way as Sw1 doesn`t work and we need to direct default route to Sw1 to make it working ?

Again sw2 is just layer-2 and that one IP you gave it is for managing the switch itself but all the inter-vlan routing is done on sw1. Also, on sw2, the reason that you need to have a default route to sw1 is that other subnets can reach sw2. Again this IP on sw2 is just for management, so you can telnet or ssh to the switch.

HTH

View solution in original post

CreatePlease to create content
Content for Community-Ad