Applying a IP address to multiple interfaces on 2911 (Packet Tracer)

[andydenley]

Hi All, 

Please excuse this post if I am lacking any information, this is my first post to the support forums. My background is in Wintel servers and SANs and have just started down this track. 

I am starting my CCNA and have configured a basic network (/24) with a single router (2911) and 2 switches (2960) and configured some VLAN's for Data/Wireless and Voice on the switches and each switch is plugged into a Gi ports on the two gigabit Ethernet ports on the router. Gi0/1 and Gi0/2. 

Now what I am thinking may not be possible on a router as you can with a switch. But in my switches I have configured VLAN 100 (data) and assigned a IP address (10.88.9.253/24) to it and then assigned the VLAN to a range of interfaces a PC can talk to the switch via ICMP. 

Now should I configure my uplink ports on my switch as a trunk to the router to carry the VLAN's? I am assuming so. 

interface GigabitEthernet0/1

switchport trunk native vlan 100

switchport trunk allowed vlan 100,120,150

switchport mode trunk

However is it possible on a router to assign a IP address to both Gi0/1 and Gi0/2 via a VLAN and then have the links from each switch going into routers Gi0/1 and Gi0/2 and have that router respond with a single IP address on both links?

I have found lots of information on configuring a IP for an interface on routers, and examined some configurations of existing routers. But the only IU have seen that the vlan is assigned to a single interface. 

but I am missing something here?

If someone could put me on the right track here or tell me what I am missing that would be great. 

Regards,

Andy

[Jon Marshall]

Andy

It's not clear whether you are routing the vlans on the 2960 switches or you want to route them on the router.

If you are creating SVIs on the switches then you don't need to extend the vlans to the router ie. you could use L3 connections and then have routes to get between the switches.

It depends on what feature set you have on the 2960s as to whether they can route between vlans.

If you want to route the vlans off the router then as Vivek says you need subinterfaces and you make the default gateway for clients the subinterface IP for their vlan.

As Rick says ISRs do support etherchannel but the switches would need to be stacked and support MEC otherwise you could not have an etherchannel going to two different switches.

If your switches aren't in a stack or they don't support it then you cannot use etherchannel from the ISR.

It really depends on what you are trying to do and what your switches support.

Jon

[mlund]

Hi

It can be done with the feature IRB.

See below link for explanation.

http://www.cisco.com/c/en/us/support/docs/lan-switching/integrated-routing-bridging-irb/17054-741-10.html

/Mikael

[Richard Burts]

Mikael

IRB is an interesting suggestion and it would satisfy part of what Andy was looking for in the original post, which is to be able to have both router interfaces use the same IP address. But the original post is also clear that the switch ports are configured with trunking for 3 VLANs and he wants the router to process the 3 VLANs. I do not believe that IRB would be able to do anything with tagged frames.

HTH

Rick

[mlund]

Hi Rick

I missed that one, but I think it's worth trying this. (haven't done it myself, so it might not work)

bridge irb

int bvi 1

 ip address <nr>

int bvi2

 ip addr <nr>

int bvi 3

 ip address <nr>

int g0/1.100

encap dot1q 100

 bridge-group 1

int g0/1.120

 encap dot1q 120

 bridge-group 2

int g0/1.150

 encap dot1q 150

 bridge-group 3

int g0/2.100

encap dot1q 100

 bridge-group 1

int g0/2.120

 encap dot1q 120

 bridge-group 2

int g0/2.150

 encap dot1q 150

 bridge-group 3

bridge 1 prot ieee

bridge 1 route ip

bridge 2 prot ieee

bridge 2 route ip

bridge 3 prot ieee

bridge 3 route ip

As I said, don't know if it works.

/Mikael

[andydenley]

Hello All again, 

So after some exploration, I found the following worked for me and remembering I am using packet tracer (as noted in subject line) that: 

1) IRB is not supported on my 2911. Didn't understand the "bridge" command under configure mode. Maybe this is a newbie thing. 

2) Etherchannel works on the native Gi0/1 - 3 interfaces but it would seem I cannot assign my other two IP adresses to these port-channels when assigning to an interface??. Also reading the notes from the document I found I dont think I can create more then one port-channel? by Again maybe a newbie thing.. 

What I did was add a 4 port fast Ethernet HWIC-4ESW to my 2911 and configured them as trunks. Then it started being able to talk from my clients and switches to the router. 

Config of router 1:

interface FastEthernet0/1/0
switchport trunk native vlan 100
switchport trunk allowed vlan 100,120,150
switchport mode trunk
!
interface FastEthernet0/1/1
switchport trunk native vlan 100
switchport trunk allowed vlan 100,120,150
switchport mode trunk
!
interface Vlan100
name data
ip address 10.64.88.1 255.255.255.0
!
interface Vlan120
name wireless
ip address 10.64.188.1 255.255.255.0
!
interface Vlan150
name voice
ip address 10.64.288.1 255.255.255.0

I am not sure if that will break my routing at a later stage if I use the HWIC for my interfaces. But from my testing I can route traffic from my intern VLAN's over my serial link to other networks. 

Would this configuration using the 4 port HWIC card have any adverse effect on my routing choices later as I build and expand the network? 

Currently I have a serial link to my "hub" router (2911 and using RIP v2 based on a geographical region in the design. I plan to use OSPF on other geographical parts of my network as I learn more about routing protocols and expand it further. 

Again this is all in packet tracer, so just in case thinks this is lab or real world it certainly isnt just in case you forgot... 

many thanks for your help and suggestions so far. 

Regards,

Andy

[Richard Burts · Accepted solution]

Andy

Using the Ethernet switch module is a good solution. It certainly does the trunking and as you have discovered you can route from the VLANs defined for the switch to the other router interfaces. You ask if using the switch module would have any adverse effect on your routing choices and I do not see anything about using the switch module that would have any impact on your routing choices.

HTH

Rick

[rosaho]

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