intervlan question

[dkblee]

hi!

if i'm configuring subinterfaces at one router that's connected to a switch, is it neccessary for me to do rip or static route to those vlan that i created?

Will that be neccessary for me to access one vlan to another?

Thks!

[Prashanth Krishnappa]

Nope.. No RIP/Static routing needed on the router to just route between subinterfaces.

Configure the switch port to be a trunk and also point your default gateways on the clients to the correct subinterface IP address.

If you need to get past the router, you will need some routing/static routes

[dnewell24]

router(config)#ip routing

This is all you need. And this should be enabled by default.

Issue the show ip route command to verify.

You would want to use a routing protocol to distribute the routing information base (RIB) between your router and neighboring routers. Static would be used to tell your router how to get to "not directly connected" networks and the next hop info. Directly connected networks will populate the RIB if ip routing is enabled.

[dkblee]

for router 2620 router, any idea what encapsulation is it using? isl or dot1q? what's the different between these 2? Thks!

[Prashanth Krishnappa]

ISL is Cisco proprietary, dot1q is IEEE standard. The way they encapsulate frames is different. With dot1q, the native VLAN is untagged. Frame formats are at

http://www.cisco.com/warp/public/473/741_4.html

2620 supports both depending on what IOS/feature set you have. But I would go with dot1q. Take a look at table 2 in the following page

http://www.cisco.com/warp/public/473/50.shtml#prereq

[dkblee]

hi! what do you meant by the native vlan is untagged?

Thks!

[Kevin Dorrell]

802.1Q trunking works by adding a small tag to each Ethernet frame to show which VLAN the frame belongs to. However, there is one VLAN which is designated as the "native VLAN" of the port. Frames for this VLAN are not tagged before transmitting them. When the other end of the link sees an untagged frame, it assumes it belongs to the native VLAN.

I'll leave to you to imagine what happens if the native VLAN is configured differently on the two sides of the link!

Kevin Dorrell

Luxembourg

[milan.kulik]

Hi,

here is a detailed "how to" document:

http://www.cisco.com/warp/customer/473/50.pdf

Regards,

Milan

[dkblee]

hi! If i got multiple routers connected to each other and for the vlan routing to work, do i need to assign an ip for every interface that's used to connect each router/switch?

In order to user rip,eigrp, is it a must to give an ip to every interfaces that is interconnectecting?

Thks!

[dkblee]

hi! If i got multiple routers connected to each other and for the vlan routing to work, do i need to assign an ip for every interface that's used to connect each router/switch?

In order to user rip,eigrp, is it a must to give an ip to every interfaces that is interconnectecting?

Thks!

[dkblee]

hi! in addition to my previous question, can i assign a range of ip specifically for the routers and switches? For e.g. Ip range 10.71.40.1-10.71.40.254 will be reserved to be used on all the routers' interfaces and switches in my network, whereas my clients connected to my switch will have several vlans that's using different ip range from above. will that work for rip eg. if i'm using the command "network 10.71.40.254"and etc for all the switches and routers? Thks!

[jswaim]

from what I can make out, you have multiple L3 routers and L2 switches. They are interconnected and you are running a routing protocol.

First, you must assign IP subnet addresses to the interconnecting links between L3 devices for the routing protocol to work. Secondly, you can assign /32 network addresses from the /24 you described to loopback interfaces on L3 routers and switches ONLY (these will show up as /32 networks in the routing table). The L2 switches require that you either trunk a management vlan across the network and assign an ip address to each switch. You can use the same /24, but be carefull not to use addresses from those already assigned to loopback interfaces, or they will overlap. You will need to have a L3 interface configured on the network to provide the L3 connectivity to this "management" vlan. Otherwise, the switches will only be able to "talk" to each other.

[dkblee]

hi! if i interpret you correctly.

i can have 10.71.40.1-10.71.40.254 for all my switches and routers interconnecting interfaces,

whereas my clients connected to all my switches, i can have client' ip such as 10.71.10.1, 10.71.11.1 and etc. is that right?

what do you meant by loopback?

what do you meant by?"(these will show up as /32 networks in the routing table). "

Thks!