Bridging Ethernet over an IP network using DLSw+

Networking Blog » Bridging Ethernet over an IP network using DLSw+.

 

dlsw

 

Setting up the bridge-group on both routers and assign the respective interface to it.

maria
bridge irb
bridge 1 protocol ieee
!
interface FastEthernet0/0
 description Link to lan 192.168.222.0/24
 no ip address
 bridge-group 1
end
hilde
bridge irb
bridge 1 protocol ieee
!
interface FastEthernet0/1
 description Link to lan 192.168.222.0/24
 no ip address
 bridge-group 1
end

Last but not least, you have to setup Data Link Switching on both routers and add it to the bridge-group.

maria
dlsw local-peer peer-id 172.16.17.1
dlsw remote-peer 0 tcp 172.16.17.6
dlsw bridge-group 1
hilde
dlsw local-peer peer-id 172.16.17.6
dlsw remote-peer 0 tcp 172.16.17.1
dlsw bridge-group 1

You can find a nice configuration guide for DLSw+ in the Cisco Support Wiki.

Verification/Troubleshooting

To verify, if your DLSw+ connection is established, you can consult the show dlsw peers command on both routers.
With it, you get some informations e.g. session-state and -duration, received and transmitted packets and so on…

maria#sh dlsw peers
Peers:                state     pkts_rx   pkts_tx  type  drops ckts TCP   uptime
 TCP 172.16.17.6     CONNECT       6690      2631  conf      0    1   0 02:51:00
Total number of connected peers: 1
Total number of connections:     1

hilde#sh dlsw peers
Peers:                state     pkts_rx   pkts_tx  type  drops ckts TCP   uptime
 TCP 172.16.17.1     CONNECT       2638      6700  conf      0    1   0 02:51:08
Total number of connected peers: 1
Total number of connections:     1

There are further flavors for the show dlsw command and several debug possibilites, but i wouldn’t go more in detail now.

show dlsw ?
  capabilities   Display DLSw capabilities information
  circuits       Display DLSw circuit information
  fastcache      Display DLSw fast cache for FST and Direct
  local-circuit  Display DLSw local circuits
  peers          Display DLSw peer information
  reachability   Display DLSw reachability information
  statistics     Display DLSw statistical information
  transparent    Display MAC address mappings

debug dlsw ?
  border-peers   Debug DLSw border peer events
  core           Debug DLSw core
  local-circuit  Debug DLSw local circuit events
  peers          Debug DLSw peer events
  reachability   Debug DLSw reachability (explorer traffic)
  rsvp           Debug DLSw rsvp
  transparent    Debug DLSw Ethernet redundancy Master-Slave & Circuit events
  <cr>

An extensive troubleshooting guide for DLSw+ can be found on the Cisco website.

To get more information about the bridge, there are some few show commands available.

maria#sh bridge 1
Total of 300 station blocks, 298 free
Codes: P - permanent, S - self
Bridge Group 1:
    Address       Action   Interface       Age   RX count   TX count
000c.29af.4431   forward   FastEthernet0/0   0       1787       1602
000c.2928.27e3   forward   DLSw Port0        0       2752       1598

hilde#sh bridge 1
Total of 300 station blocks, 298 free
Codes: P - permanent, S - self
Bridge Group 1:
    Address       Action   Interface       Age   RX count   TX count
000c.29af.4431   forward   DLSw Port0        0       1799       1597
000c.2928.27e3   forward   FastEthernet0/1   0       2795       1598

I was looking for bridge specific debug commands, but couldn’t find some.
Due to the lack of troubleshooting alternatives, i avoid bridge-groups whenever it’s possible. But in special cases it’s the only way out.

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