03-03-2009 06:23 AM - edited 03-04-2019 03:47 AM
I have two routers connected via 64K serial interfaces....The ip address on the ethernet of both routers is in the same subnet....My questions is..>Can I bridge like subnets across those serial interfaces...I need to maintain IP integrity at both ends for management purposes...perhaps a tunnel...I just don't know..can't remember...
03-03-2009 07:25 AM
Hello,
you need to use IRB and bridging over the serial interfaces
int eth0
no ip address
bridge-group 1
int ser0/0
ip addr
bridge-group 1
int bv1
! here the shared subnet
ip address x.x.x.1 255.255.255.0
bridge 1 protocol ieee
bridge 1 route ip
do it on both ends/routers
Hope to help
Giuseppe
03-03-2009 08:18 AM
Do the serial interfaces need a 30 bit IP range to connect them///or no ip address on the serial
03-03-2009 08:33 AM
Hello,
you should be fine with no ip address on the serial interfaces.
I've noticed that you say you have only 64kbps link so a bridging solution is probably troublesome:
broadcast traffic is enough to saturate the link if this is a real production network and not a lab.
Hope to help
Giuseppe
03-03-2009 09:14 AM
The bandwidth is small but, the application is tiny..just polling a RTU...once evrey 5 minutes...the whole network is for that...thanks again
03-03-2009 09:20 AM
Once you configure bridging, the WAN won't be used just for that small application transfer but every single broadcast in either side of the network will traverse that link.
In a LAN segment, broadcast traffic is barely a problem since you usually have a LAN with speeds of 10Mbps or better.
With this design, your LAN speed will be as low as 64kbps depending on the switch/router root placement.
I strongly suggest to revisit this design.
__
Edison.
03-03-2009 07:45 AM
Be aware that extending your Layer2 topology over slow unreliable WAN links will create atrocious performance issues in the network at both ends of the link.
I suggest re-examining your network and provide a Layer3 design that fulfills this need without going the bridging path.
HTH,
__
Edison.
03-03-2009 07:47 AM
Edison
Off the top of your head do you know if L2TPv3 is any better in terms of performance across a WAN link ?
Jon
03-03-2009 07:52 AM
Jon,
They both accomplish the same thing, i.e. extending a L2 topology.
With that said, L2TPv3 is mostly used to accommodate customers on a point-to-point virtual connection.
For instance, a service provider would use 2 routers with L3 inter-connectivity and assign a L2 port for each CE. The CEs, in turn, will be able to create L3 point-to-point connection, pretty much like your typical point-to-point serial link. In this case, that's a proper use of L2TPv3 implementation.
__
Edison.
03-03-2009 08:52 AM
Jon,
Another thing just came to my head :)
When you enable bridging between 2 routers, say a service provider doing what I mentioned before, you are automatically enabling spanning-tree and a root election will take place. This add some overhead over WAN links.
While, when you enable L2TPv3, you are creating a pseudowire for devices that are attached 'xconnect' interfaces. No spanning-tree is running on the service provider devices - hence it is much cleaner solution.
__
Edison.
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