Split MultiLink Trunking

1
Split Multi-Link Trunking

• Didier DUCARRE
• Switching specialist

2
Test Network
.10
Port A
Port B
Windows NT 4.0 SP 6 Intel EtherExpress Pro/100
Dual port Adapter
server
4/3
8/3
IST
1/1
1/1
8600A
8600B
2/1
2/1
2/2
1/3
.1
.2
.20
10.10.20.X/24 Vlan 20
2/2
2/1
IST Link 10.10.10.X/24 Vlan 10
8100
1/20
pc
.50
3
Passport 8100 Configuration

• Reset switch to factory defaults
• All ports belong to vlan1, no other vlan need
  to be configured
• Create MLT Trunk 1
• add port 2/1 and 2/2 to trunk members
• add mlt1 to vlan1
• Remove ports from spanning tree
• stp disable for ports 2/1 and 2/2
• Assign an ip address, subnet mask and default
  gateway to your management port (not mandatory)
• connect a cable between management port to any
  port belonging to vlan1
• ip10.10.20.20 / sm 255.255.255.0
• define default route for routed traffic
  (gw10.10.20.1)

4
Passport 8600 Configuration

• Use latest 3.20 build and reset config to
  factorydefaults.
• Create vlan 10
• ip 10.10.10.1 / sm 255.255.255.0
• add mlt 1
• Create vlan 20
• ip 10.10.20.1 / sm 255.255.255.0
• add mlt 2 mlt 3
• Create mlt 1 (IST)
• enable tagging, add ports (1/1,2/1), add vlans
  (10,20) then under ist specify peer ip address
  (10.10.10.2) vlan id (10)
• Create mlt 2 mlt 3(SMLT)
• under smlt, give smlt-id (2 3), add port (2/2
  (smlt-id 2) and 8/3 (smlt-id 3))

5
Server Configuration 1/2

• Select Automatic Fault Tolerance Mode
• AFT Only

6
Server Configuration 2/2

• IP address will be common on port A B

7
IST/SMLT link states
Once all switches are up and you have
connectivity you get messages on console (as well
in log, show log file to display) 04/25/01
142006 smltIstSessionUp 04/25/01 152006
SMLT 2 UP 04/25/01 152006 SMLT 3 UP show mlt
info command give IST/SMLT status
PORT MLT MLT PORT
VLAN MLTID IFINDEX NAME TYPE ADMIN
CURRENT MEMBERS IDS ----------------------
--------------------------------------------------
----- 1 4096 8600A-8600B trunk ist
ist 1/1,2/1 10 20 2 4097
8600A-8100 access smlt smlt 2/2
20 3 4098 8600A-server access smlt
smlt 8/3 20 IST status is
always ist even if ports 1/1 and 2/1 are
down SMLT status can be smlt (port 2/2 or 8/3 up)
or norm (port 2/2 or 8/3 down)
8
Removing IST/SMLT links
If you disconnect IST link (ports 1/1 and 2/1)
you have 04/26/01 152149 Link
Down(1/1) 04/26/01 152156 smltIstSessionDown
04/26/01 152156 Link Down(2/1) If you
disconnect an smlt port you have 04/25/01
152621 SMLT 2 DOWN 04/25/01 152621 Link
Down(2/2) If you reconnect it you have
04/25/01 152710 SMLT 2 UP 04/25/01
152710 Link Up(2/2) More detail with trace
level 25 2, but it is really verbose
9
What is the path ?

• Check forwarding databases on 8600A and 8600B for
  vlan 20
• 8600A5 show vlan info fdb-entry 20
• You will get pc, server and 8100 mac addresses (2
  for 8100, one related to management interface and
  second for discovery protocol SONMP)
• VLAN MAC
  QOS SMLT
• ID STATUS ADDRESS INTERFACE
  MONITOR LEVEL REMOTE
• --------------------------------------------------
  -------------------------
• 20 learned 0010a4e06f43 8600A-8100
  false 1 true
• 20 self 00802d359a01 -
  false 0 false
• 20 learned 00802dac6201 8600A-8600B
  false 1 true
• 20 learned 00d0b781c464 8600A-server
  false 1 true
• 20 learned 00e07bb10880 8600A-8100
  false 1 false
• 20 learned 00e07bb10881 8600A-8100
  false 1 true
• True coming from IST link / False coming
  from SMLT link

10
Response time 1/2
Start a continuous ping from pc to server (ping
t 10.10.20.10) Disconnect link between
8100-8600 (Use previous slide to find active path
otherwise ping will not loose any echo) Reply
from 10.10.20.10 bytes32 timelt10ms
TTL128 Request timed out. 1 or 2 echo
losts Reply from 10.10.20.10 bytes32 timelt10ms
TTL128 If you reconnect it you have Reply
from 10.10.20.10 bytes32 timelt10ms
TTL128 Request timed out. Request timed
out. 4 to 6 echo losts Request timed
out. Request timed out. Reply from 10.10.20.10
bytes32 timelt10ms TTL128
11
Response time 2/2
Now power down active 8600 (the one on which
frame goes) Reply from 10.10.20.10 bytes32
timelt10ms TTL128 Request timed out. 1 or 2
echo losts Reply from 10.10.20.10 bytes32
timelt10ms TTL128 If you switch it on. Reply
from 10.10.20.10 bytes32 timelt10ms
TTL128 Request timed out. Request timed
out. 4 to 6 echo losts Request timed
out. Request timed out. Reply from 10.10.20.10
bytes32 timelt10ms TTL128