RE: STP and FR

From: Brian Dennis (brian@labforge.com)
Date: Fri Mar 07 2003 - 15:08:04 GMT-3


Gerry,
Just think about how a bridge works and you'll be able to solve this
problem yourself. Will a standard bridge forward frames back out the
same interface it is was received on? This is what you are asking the
central bridge to do.

Also are you testing with IP or using another protocol to test with? You
can't bridge and route IP at the same time on a standard interface. You
need a BVI to do that.

Brian Dennis, CCIE #2210 (R&S/ISP Dial/Security)
brian@labforge.com
http://www.labforge.com

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Gerry Hilton
Sent: Friday, March 07, 2003 10:25 AM
To: ccielab@groupstudy.com
Subject: STP and FR

If you have 3 routers configured for FR and transparent bridging, with
the central router a multipoint interface and the end routers plain
serial interfaces, does the central router have to be the root bridge?
 I cannot get it to work unless this is the case. If the central
routers is not given a lower bridge priority then each of the end
routers think that they are the root.

1 end router:

interface Serial0
 ip address 150.50.24.4 255.255.255.0
 encapsulation frame-relay
 no ip route-cache
 no ip mroute-cache
 frame-relay map bridge 401 broadcast
 bridge-group 1
end

Central router:

interface Serial0.247 multipoint
 no ip route-cache
 frame-relay map bridge 107 broadcast
 frame-relay map bridge 104 broadcast
 bridge-group 1
end

2nd end router:

interface Serial0
 ip address 150.50.24.7 255.255.255.0
 encapsulation frame-relay
 no ip route-cache
 no ip mroute-cache
 frame-relay map bridge 701 broadcast
 bridge-group 1
end

Thanks,
  Gerry



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