Instruction/ maintenance manual of the product AT-9924T/4SP-A-20 Allied Telesis
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C613-16092-00 REV D www .alliedtelesis.co m AlliedW ar e TM OS How T o | Intr oduction Putting a ring of Ethernet switches at the cor e of a network is a simple wa y to increase the network’ s resilience—such a netw ork is no longer susceptible to a single point of failure.
Page 2 | AlliedW are™ OS How T o Note: EPSR Which products and softwar e versions does it apply to? • "Example 3: EPSR and RSTP" on page 17 • "Example 4: EPSR with Nested VLANs&qu.
Page 3 | AlliedW are™ OS How T o Note: EPSR Ho w EPSR W orks Ho w EPSR W orks EPSR operates on ph ysical rings of switches (note, not on meshed netw orks). When all nodes and links in the ring are up , EPSR prev ents a loop by blocking data transmission acr oss one por t.
Page 4 | AlliedW are™ OS How T o Note: EPSR Ho w EPSR W orks Establishing a Ring Once y ou ha ve configur ed EPSR on the switches, the following ste ps complete the EPSR ring: 1. The master node creates an EPSR Health message and sends it out the primary por t.
Page 5 | AlliedW are™ OS How T o Note: EPSR Ho w EPSR W orks Detecting a Fault EPSR uses a fault detection sc heme that alerts the ring when a break occurs, instea d of using a spanning tree- lik e calculation to determin e the best path. The ring then automatically heals itself by sending traffic over a pr otected rev erse path.
Page 6 | AlliedW are™ OS How T o Note: EPSR Ho w EPSR W orks new configuration, the nodes (master and transi t) r e-learn their la yer 2 ad dresses. During this period, the master node continues to se nd Health messages ov er the control VLAN. This situation continues until the faulty link or node is r epaired.
Page 7 | AlliedW are™ OS How T o Note: EPSR Ho w EPSR W orks Restoring Normal Operation Master Node Once the fault has been fixe d, the master node’ s Health messages tra verse the whole ring and arriv e at the master node’ s secondary por t . The master node then restor es normal conditions by: 1.
Page 8 | AlliedW are™ OS How T o Note: EPSR Ho w T o Configure EPSR Ho w T o Configur e EPSR This section first outlines, step-by-step , how to configur e EPSR. Then it discusses changing the settings for the contr ol VLAN , if y ou need to do this after initial configuration.
Page 9 | AlliedW are™ OS How T o Note: EPSR Ho w T o Configure EPSR If y ou lea ve all the ring port s in the default VLAN (vlan 1 ), they will cr eate a loo p , unless vlan 1 is par t of the EPSR domain.
Page 10 | AlliedW are™ OS How T o Note: EPSR Ho w T o Configure EPSR Modifying the Contr ol VLAN Y ou cannot modify the control VLAN while EPSR is enabled. If you tr y to remov e or add ports to the control VLAN, the switch generates an err or message as follows: Disable the EPSR domain and then mak e the requ ir ed changes.
Page 11 | AlliedW are™ OS How T o Note: EPSR Example 1 : A Basic Ring Example 1 : A Basic Ring This example builds a simple 3-switch ring wi th one data VLAN, as shown in the following diagram. Contr ol packets ar e transm itted around the ring on vlan 1 000 and data packets on vlan2.
Page 12 | AlliedW are™ OS How T o Note: EPSR Example 1 : A Basic Ring delete vlan=1 port=1-2 This step creates the domain, spec ifying that this switch is the master node. It also specifies which VLAN is the contr ol VLAN and which por t is the primar y por t.
Page 13 | AlliedW are™ OS How T o Note: EPSR Example 1 : A Basic Ring This step creates the domain, spec ifying that this switch is the transit node. It also specifies which VLAN is the contr ol VLAN. create epsr=test mode=transit controlvlan=vlan1000 add epsr=test datavlan=vlan2 enable epsr=test 6.
Page 14 | AlliedW are™ OS How T o Note: EPSR Example 2: A Double Ring Example 2: A Double Ring This example adds to the previous ring by making tw o domain s, as shown in the following diagram. The master node for domain 1 is the same as in the pre v ious example (except that the domain has been r enamed).
Page 15 | AlliedW are™ OS How T o Note: EPSR Example 2: A Double Ring This transit node is the same as in the pr ev ious example (except that the domain has been re n am e d ) .
Page 16 | AlliedW are™ OS How T o Note: EPSR Example 2: A Double Ring Configur e EPSR: create epsr=domain2 mode=transit controlvlan=vlan40 add epsr=domain2 datavlan=vlan50 enable epsr=domain2 T wo separate EPSR domains are configur ed on this switch.
Page 17 | AlliedW are™ OS How T o Note: EPSR Example 3: EPSR and RSTP Example 3: EPSR and RSTP This example uses EPSR to pr otect one ring and RSTP to protect another o verla pping ring.
Page 18 | AlliedW are™ OS How T o Note: EPSR Example 3: EPSR and RSTP This transit node (B) is the sa me as in the pr evious example . create vlan=vlan1000 vid=1000 add vlan=1000 port=1-2 frame=tagg.
Page 19 | AlliedW are™ OS How T o Note: EPSR Example 3: EPSR and RSTP Configure the contr ol VLAN for EPSR: create vlan=vlan1000 vid=1000 add vlan=1000 port=1-2 frame=tagged Configure the data VLAN .
Page 20 | AlliedW are™ OS How T o Note: EPSR Example 4: EPSR with Nested VLANs Example 4: EPSR with Nested VLANs In this example: • client switches A and C ar e in the same end-user VLAN (vlan20) .
Page 21 | AlliedW are™ OS How T o Note: EPSR Example 4: EPSR with Nested VLANs Configure the EPSR contr ol VLAN: create vlan=vlan100 vid=100 add vlan=100 port=1-2 frame=tagged Configure vlan50. This VLAN acts as both th e neste d VLAN and the EPSR data VLAN.
Page 22 | AlliedW are™ OS How T o Note: EPSR Example 4: EPSR with Nested VLANs create vlan=vlan20 vid=20 add vlan=20 port=20 frame=tagged enable ip add ip interface=vlan20 ip=192.168.20.10 create vlan=vlan200 vid=200 add vlan=200 port=10 frame=tagged enable ip add ip interface=vlan200 ip=192.
Page 23 | AlliedW are™ OS How T o Note: EPSR Example 5: EPSR with manage ment stacking Example 5: EPSR with mana gement stacking In this example: • three switches are stack ed together , so y ou c.
Page 24 | AlliedW are™ OS How T o Note: EPSR Example 5: EPSR with manage ment stacking The following commands mu st be entered in to the CLI of this particular switch.
Page 25 | AlliedW are™ OS How T o Note: EPSR Example 5: EPSR with manage ment stacking The stack now exists, so you can configure all thre e switches fr om the CLI of the master node (or any other of the s witches). How ev er , the por ts and IP addr esses ar e differ ent for each switch, so y ou need to mak e most of the commands host-directed.
Page 26 | AlliedW are™ OS How T o Note: EPSR Example 6: EPSR with an iMAP Example 6: EPSR with an iMAP This example is the same as "Example 1 : A Basic Ring" on page 11 except that one of the three s witches is an iMAP . W e used an A T -TN7 1 00 iMAP running 6.
Page 27 | AlliedW are™ OS How T o Note: EPSR Example 6: EPSR with an iMAP Checking the Master Node Configuration T o see a summar y , use the command: show epsr The following diagram sho ws the expected output. T o see details, use the command: show epsr=test The following diagram sho ws the expected output.
Page 28 | AlliedW are™ OS How T o Note: EPSR Example 6: EPSR with an iMAP Configur e the A T -TN7 1 00 iMAP as a T ransit Node The following diagram shows a partial script fo r the iMAP , with the commands for configuring it as a transit node.
Page 29 | AlliedW are™ OS How T o Note: EPSR Classifiers and Ha rdwa re F ilt er s T o see details, use the command: show epsr=test The following diagram sho ws the expected output.
Page 30 | AlliedW are™ OS How T o Note: EPSR P orts and Reco very Times P or ts and Reco ver y Times In practice, recov er y time in an EP SR ring is generall y between 50 and 1 00 ms. How ev er , it depends on the por t type , because this determines how long it tak es for the por t to report that it is down and send a Link-Do wn message .
Page 31 | AlliedW are™ OS How T o Note: EPSR IGMP Snooping and Reco very Times IGMP Snooping and Reco v er y Times Since Software V ersion 28 1 -03, IGMP snooping includes quer y so licitation , a new f eature that minimises loss of multicast data after a topology change.
Page 32 | AlliedW are™ OS How T o Note: EPSR EPSR State and Setting s EPSR State and Settings T o display the EPSR state , the attached VLANs, the ring ports, and the timer values, use the command: show epsr Master Node in a Complete Ring The following diagram sho ws the output for a mast er node in a ring that is in a state of Complete.
Page 33 | AlliedW are™ OS How T o Note: EPSR EPSR State and Setting s Master Node in a Failed Ring In contrast, the follo wing diagram shows the output for a master node in a ring that is in a Failed state . Both ring por ts are now f orwarding. EPSR Information -------------------------- ---------------------------------------------- Name .
Page 34 | AlliedW are™ OS How T o Note: EPSR SNMP T raps SNMP T raps Y ou can use SNMP traps to notify you when e vents occur in the EPSR ring. Download the latest v ersion of the Allied T elesis Enterprise MIB fr om www .alliedtelesis.co.nz/sup port/updates/patches.
Page 35 | AlliedW are™ OS How T o Note: EPSR Counters Counters The EPSR counters r ecord th e n umber of EPSR messages that the CPU receiv ed and transmitted.
Page 36 | AlliedW are™ OS How T o Note: EPSR Debugging Debugging This section walks you through the EPSR debuggi ng output as links go do wn and come back up again. The debugging output comes from the ring in "Example 1 : A Basic Ring" on page 11 .
Page 37 | AlliedW are™ OS How T o Note: EPSR Debugging The master node contin ues sending Health me ssages, and incr ements the Hello Sequence number with each message. If all nodes and links in the ring are intact, these He alth messages are the onl y debugging output you see.
Page 38 | AlliedW are™ OS How T o Note: EPSR Debugging The master node receiv es a Link-Down message on its secondar y po rt (por t 2) from transit node B, which is at the other end of the br ok en link. In the System field, this output shows the MA C addr ess of the sour ce of the message—the transit node in this case .
Page 39 | AlliedW are™ OS How T o Note: EPSR Debugging The Hello timer expir es, which w ould normally trigger the mas ter node to send a Health message out the primar y por t. How ev er , the link between the primar y port and the neighbouring transit no de is down, so the ma ster node does n ot se nd the Health message.
Page 40 | AlliedW are™ OS How T o Note: EPSR Debugging The master node receiv es the Health message on its secondar y port (por t 2). This tells it that all links on the ring are up again.
Page 41 | AlliedW are™ OS How T o Note: EPSR Debugging The master node continues transmitting and rece iving Health messages for as long as the ring sta ys in a state of Complete.
Page 42 | AlliedW are™ OS How T o Note: EPSR Debugging T ransit Node (Node B) Debug Output The following debugging shows the same e vents as the pr evious section, but on the transit node instead of the master node. It starts with the ring establis hed and in a state of Complete.
Page 43 | AlliedW are™ OS How T o Note: EPSR Debugging The transit node detects that por t 1 (between the transit node and the master n ode) has gone do wn.
Page 44 | AlliedW are™ OS How T o Note: EPSR Debugging The transit node detects that port 1 has come back up. It sends a trap and changes the EPSR state to Pre-f orwarding. Note that it lea ves port 1 block ed for vlan2, to mak e sure ther e are no loops.
Page 45 | AlliedW are™ OS How T o Note: EPSR Debugging The Health message from the pre vious step re aches the master node and sh ows it that all links in the rin g are no w up .
Page 46 | AlliedW are™ OS How T o Note: EPSR Debugging The transit node continues r eceiving Health messages for as long as the ring sta ys in a state of Complete.
Page 47 | AlliedW are™ OS How T o Note: EPSR Debugging Link Do wn Between T w o T ransit Nodes This section sho ws the debugging output when the link betw een transit node B and transit node C go es down and comes back up again.
Page 48 | AlliedW are™ OS How T o Note: EPSR Debugging When the link goes down, the master node tr ansmits a Health message but does not receiv e it on its secondar y port. The master node receiv es a Link-Down message , which tells it that a link in the ring is br oken.
Page 49 | AlliedW are™ OS How T o Note: EPSR Debugging In r esponse to the Link-Do wn message, the master node transmits a Ring-Down-Flush-FDB message out both its primar y and second ar y por ts. The message has to go out both ports to mak e sure it r eaches the nodes on both side s of the br oken link.
Page 50 | AlliedW are™ OS How T o Note: EPSR Debugging The master node continue s sending Health mess ages out its primar y por t. It does not r eceive any of these at the secondary por t, whic h tells it tha t the link is still down. The master node transmits a Health message an d receiv es it at the secondar y por t.
Page 51 | AlliedW are™ OS How T o Note: EPSR Debugging Now that the ring is back up, the master node blocks its secondar y port for the data VLAN, transmits a Ring-Up -Flush-FDB message , flushes its FDB, sends a trap , and changes the EPSR state to Complete .
Page 52 | AlliedW are™ OS How T o Note: EPSR Debugging The master node continues transmitting and receiv ing Health messages for as long as the ring sta ys in a state of Complete.
Page 53 | AlliedW are™ OS How T o Note: EPSR Debugging T ransit Node (Node B) Debug Output The following debugging shows the same e vents as the prev ious sectio n, but on the transit node instead of the master node. It starts with the ring establis hed and in a state of Complete.
Page 54 | AlliedW are™ OS How T o Note: EPSR Debugging In the meanwhile , the master node has r eceived a Link-Do wn message from the s witch at the other end of the br oken link (in step 3 on page 48 ). Therefor e, the master node realises that the ring is br oken and acts accordingly .
Page 55 | AlliedW are™ OS How T o Note: EPSR Debugging The transit node re ceives Heal th messages fr om the master node . These ha ve a state of Failed, which shows that the ring is still br oken. This is the pack et shown in step 6 on page 50 of the master node debug output.
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If you have not bought Allied Telesis AT-9924T/4SP-A-20 yet, this is a good time to familiarize yourself with the basic data on the product. First of all view first pages of the manual, you can find above. You should find there the most important technical data Allied Telesis AT-9924T/4SP-A-20 - thus you can check whether the hardware meets your expectations. When delving into next pages of the user manual, Allied Telesis AT-9924T/4SP-A-20 you will learn all the available features of the product, as well as information on its operation. The information that you get Allied Telesis AT-9924T/4SP-A-20 will certainly help you make a decision on the purchase.
If you already are a holder of Allied Telesis AT-9924T/4SP-A-20, but have not read the manual yet, you should do it for the reasons described above. You will learn then if you properly used the available features, and whether you have not made any mistakes, which can shorten the lifetime Allied Telesis AT-9924T/4SP-A-20.
However, one of the most important roles played by the user manual is to help in solving problems with Allied Telesis AT-9924T/4SP-A-20. Almost always you will find there Troubleshooting, which are the most frequently occurring failures and malfunctions of the device Allied Telesis AT-9924T/4SP-A-20 along with tips on how to solve them. Even if you fail to solve the problem, the manual will show you a further procedure – contact to the customer service center or the nearest service center
