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Community Member

Bridging over serial link !

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

3 REPLIES
Hall of Fame Super Silver

Re: Bridging over serial link !

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

Community Member

Re: Bridging over serial link !

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

Hall of Fame Super Silver

Re: Bridging over serial link !

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

http://www.cisco.com/en/US/docs/ios/bridging/configuration/guide/br_transprnt_brdg_ps6350_TSD_Products_Configuration_Guide_Chapter.html#wp1003896

Hope to help

Giuseppe

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