UDP Broadcasts across Layer 3 devices

[NinjaTurtle777]

Hi:

I need a little help with GRE tunnels. My end goal is to push DIS UDP broadcasts and other TCP traffic from LAN A to LAN B. I need to push these broadcasts across some layer 3 encryption devices. So, I need to encapsulate the layer 2 UDP DIS broadcasts in a Layer 3 wrapper. This way I can route them across the Layer 3 devices on both ends. The bridge router A receive DIS broadcasts from their serial interfaces (s0/0,s0/1) and from a local fe0/0 interface (LAN A). These are the broadcasts that I need to push to LAN B. These interfaces on Bridge Router A are part of bridge group 1. I need to add the other fe0/1 interface to the bridge group 1, this way fe0/1 can receive the DIS broadcasts. I then need to connect fe0/1 on bridge router A to the fe0/0 interface on the GRE Router A. The fe0/1 interface on Bridge Router A will forward DIS broadcasts to the fe0/0 interface on GRE Router A. No problem so far. Now the reason why I have a separate bridge and GRE router is that you cannot (at least I was told) establish a GRE tunnel on a bridged interface.

So, right now I have some broadcast hitting the fe0/0 interface on the GRE router. This router will do nothing with the broadcast unless I create a GRE tunnel from GRE Router A to GRE Router B. The connection between the Layer 3 encryption devices is already established and working.

Here are the conceptual IP’s:

Bridged Router A:

Fe/0/0: 10.10.1.1/24
Fe0/1: 10.10.2.1/24

GRE Router A

Fe0/0: 10.10.2.2/24
Fe0/1: 10.10.3.1/24

GRE Router B

Fe0/0: 10.10.7.1/24
Fe0/1: 10.10.8.1/24

Bridged Router B:

Fe0/0: 10.10.8.2/24
Fe0/1: 10.10.9.1/24

Here is a little diagram:

LANA--SwA--(fe0/0)BridgeRouterA(fe0/1)--(fe0/0)GRERouterA(fe0/1)--L3Device--WAN--L3Device--(fe0/0)GRERouterB(fe0/1)--(fe0/0)BridgeRouterB(fe0/1)--SwB--LANB

So, I need to create a tunnel so that any broadcasts that hit 10.10.2.2 are sent to 10.10.8.1 and then to 10.10.8.2. I have seen GRE tunnel examples done different ways.

On GRE Router A can I:

Ip tunnel add tunnel0 mode gre remote 10.10.7.1 local 10.10.3.1 ttl 255
Ip link set tunnel0 up
Ip addr add 10.10.2.2 dev tunnel0
Ip route add 10.10.8.1/24 dev tunnel0

Then on GRE Router B:

Ip tunnel add tunnel1 mode gre remote 10.10.3.1 local 10.10.7.1 ttl 255
Ip link set tunnel1 up
Ip addr add 10.10.8.1 dev tunnel1
Ip route add 10.10.2.2/24 dev tunnel1

Will this Work???



Thank you…..