This is a thread from about a year ago that specifies the configuration on a
CISCO router for bridging DTC traffic.   I used it successfully for two
remote DTC-48s over a Frame-Relay wide area network from a single HP-3000.
Note the "NO BRIDGE 1 ACQUIRE".   This is critical to prevent flooding the
routers and network with bridged traffic.   The MAC address from the HP-3000
is forwarded from interface to interface on each router hop to the DTC, and
the MAC address of the DTC is forwarded along each hop from the remote site
back to the HP-3000.   The DTC's can be downloaded and managed from the Host
based NMMGR on the HP-3000.   The download can take a while depending on the
bandwidth, but once the download is done, the throughput performance was
more than adequate.


Eucaristo,
Tom Genute
Phone:  (212) 437-1744

Kara wrote:
Do the Cisco routers work for dumb terminals?  We are looking for a
cost-effective way to remove bridging from our network.  Currently, we have
dtcs at remote locations with a dtc manager centrally located which allows
dumb terminals to connect to any of our MPE or Unix systems.  Some options
we've considered were host-based dtc management or terminal servers.  I was
told that the only other option was to locate dtc managers at each site.
Then the bridging would only be on the segment between the dtc manager and
the dtc's, not on the whole network.  It's not currently a hot issue, but
will again soon, I'm sure.
Ideas?
Kara Strunk
------------------Reply separator----------------------
I've replied privately to 2 other similar messages over the past couple of
weeks. This time I decided to post it to the list for anyone else who may
also benefit from it.
Kara,

You have most everything you need already in place.  The only remaining task
is to configure bridging on the Cisco router(s).  Basically what you need to
do is configure transparent bridging on each router that needs to bridge
packets.  This alone will bridge your remote DTCs to the central site.
However, you may then experience some performance problems.  To avoid this,
create a MAC address list on both the central router and the remote
router(s).
The remote router's MAC address list should permit forwarding of packets to
and from the DTC (MAC address) on the LAN (Ethernet) port of the Cisco
router. It should also permit forwarding of packets to and from specific
server MAC addresses on the WAN (Serial) interface.  That is - the HP3000(s)
and the DTC/Manager server at your central site.
On the remote router configure "NO BRIDGE n ACQUIRE" (n is the bridge
environment number you assign to the bridge group) - otherwise the router
will acquire MAC addresses for every device on every network known to the
router and forward their packets over all network connections. If you do a
"show bridge <interface_name>", you will probably see screen after screen of
MAC addresses in the table. After setting up the MAC table, only packets
to/from the hosts defined in the MAC list will be forwarded - all others
will be discarded.
On the central router configure a MAC address table in much the same way.
If you have multiple WAN interfaces or use subinterfaces, create a MAC list
entry or each of these - pointing to the MAC address of the remote LAN's
DTC. Likewise, create an entry for each of the bridged services on the
central LAN connection. If you have multiple remote sites, you should
configure those sites before implementing these changes on your central
router. After everything is configured on the central router enter config
mode and do a "NO BRIDGE n ACQUIRE".
Below is an example of one of our remote Cisco router configs.  Note - we
use separate Frame Relay PVC's for IP and Bridging. However, this should
work just as well on a shared IP/Bridged PVC:

-----------------------------------------

!
version 11.2
service timestamps debug datetime msec localtime
service timestamps log datetime msec localtime
service password-encryption
service udp-small-servers
service tcp-small-servers
!
hostname gf_router
!
enable secret 5 xxxxxxxxxxxxxxxx
enable password 7 xxxxxxxxxxxxx
!
ip hp-host fcpl.fairfax.lib nnn.nnn.nnn.nnn
ip hp-host fcpl nnn.nnn.nnn.nnn
ip domain-name your.domain.name
ip name-server your.name.server
isdn switch-type basic-dms100
clock timezone EST -5
clock summer-time EDT recurring
!
interface Ethernet0
description Great Falls Ethernet LAN
ip address nnn.nnn.nnn.nnn nnn.nnn.nnn.nnn
loopback
priority-group 1
bridge-group 1            (Turns on bridging for this interface)
!
interface Serial0 description GF Circuit # 36.QGDQ.746758 to CH/Tech. Ops.
no ip address
encapsulation frame-relay
priority-group 1
frame-relay lmi-type ansi
!
interface Serial0.1 point-to-point
description IP PVC mapped to CH/Tech. Ops DLCI 535
ip address nnn.nnn.nnn.nnn nnn.nnn.nnn.nnn
frame-relay interface-dlci 337
!
interface Serial0.2 point-to-point description IEEE STP PVC mapped to
CH/Tech.Ops. DLCI 536 frame-relay interface-dlci 338 bridge-group 1
(Turns on bridging for this interface)
!
interface Serial1
description Spare Serial Interface
no ip address
shutdown
!
interface BRI0
no ip address
shutdown
!
router eigrp 3333
passive-interface Ethernet0
network nnn.nnn.nnn.nnn
network nnn.nnn.nnn.nnn
no auto-summary
!
no ip classless
priority-list 1 protocol bridge high
snmp-server community public RO
snmp-server community fcpl RW
snmp-server community fcpl1 RW
snmp-server host nnn.nnn.nnn.nnn host_name
bridge 1 protocol ieee                    (Defines the bridge environment)
no bridge 1 acquire                       (The Cisco default is to
"acquire")
bridge 1 address 0800.0970.1b3b forward Ethernet0         (remote DTC)
bridge 1 address 0800.09db.e15f forward Serial0.2 338     (central HP3000)
bridge 1 address 0800.0998.38df forward Serial0.2 338     (central HP3000)
bridge 1 address 0800.09c0.ca22 forward Serial0.2 338     (central DTC/Mgr.)
!
line con 0
timeout 0 0
password 7 xxxxxxxxxxxx
line aux 0
transport input all
rxspeed 2400
txspeed 2400
flowcontrol hardware
line vty 0 4
password 7 xxxxxxxxxxxxx
login
!
end

___________________________________________

Steve Barrett

    Steven P. Barrett    [log in to unmask]
<mailto:[log in to unmask]>
    Systems Analyst
    Fairfax County Public Library     (703) 222-3132 - Voice
    Technical Operations Center       (703) 222-3135 - FAX
    4000 Stringfellow Rd.
    Chantilly, VA  20151

        --- The opinions expressed here are mine alone . ---
        If God had meant for us to have distributed systems, he would have
put little brains in our hands and in our fingers.  (Unknown Author)