05-12-2009 10:11 PM - edited 03-06-2019 05:42 AM
Hi all. I have a confusion regarding transparent bridging over a serial link. My diagram is simple
R1 is connected to R2 via serial link
R2 is connected to R3 via Ethernet link.
On R1 Serial i have given IP 10.0.0.1/8
On R3 Ethernet i have IP 10.0.0.2/8.
On R2 i have the following config
bridge irb
bridge 1 protocol ieee
int se 1/0 ( with R1)
no ip address
bridge-group 1
no shut
int ethernet 0/0 (with R3)
no ip address
bridge-group 1
no shut
Now when i try to ping R3 from R1 its unsuccessful, same with R3 to R1. The main issue is i am not able to get any doc that addresses this issue !!. Can some1 point me to any doc besides Cisco IOS and IBM networking, i have already viewed it but no use :(
Kindly guide me in this
05-12-2009 10:35 PM
Hello Ovais,
also R1 has to use bridge-groups on the ethernet and on its serial interface.
Look for IRB.
L3 services can be provided by logical interface BVI x where x is the bridge-group number.
R1:
bridge 1 protocol ieee
bridge 1 route ip
int eth0
bridge-group 1
int ser0
bridge-group 1
int bvi1
ip address x.x.x.1 255.255.255.0
no shut
R3 can be normally configured
Hope to help
Giuseppe
05-13-2009 12:31 AM
Dear Giuseppe, thanks for replying. Actually this is where my confusion lies. why do i need to configure bridge group on R1 ?? When R2 knows that it has to take packet from an ethernet interface, strip off the mac-address and other info, place the l2 information for serial and simply pass it on via serial interface, then why is it not working like this ?
Actually i was looking for some document that explains this behaviour in greater depth. I am preparing for my CCIE so want to know things A-Z (to my best). I also have my company account so if you can simply forward me a doc or refer a book that explains this behaviour in detail i will be so grateful.
pls guide me in this
05-13-2009 02:36 AM
Hello Ovais,
if your requrement is to have ethernet frames bridged from the lan segment where R1:eth0 is connected to R2:eth0 segment you cannot route on R1 between eth0 and ser0.
Another way to see it is the following:
imagine that you have a black-box that works like a transparent bridge with two ports : one is connected to R1:lan segment and one is connected to R2:lan segment : an ethernet frame is received on port1 if the dest MAC is not heard on the same port the frame is sent to port2.
So inside the box you need two half-way switches with one lan arm and one arm on the wan.
about documentation see
Hope to help
Giuseppe
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