Split Trunking Support with HP Auto Port Aggregation

Transcription

1 Split Trunking Support with HP Auto Port Aggregation Overview 2 When to Use Split Trunking 6 Examples 7 Setting up Split Trunks on Cisco Switches 7 Setting up Split Trunks on Nortel Switches 9 Conclusion 12 For more information 14

2 Overview The IEEE 8023ad standard defines link aggregation on a single switch, but different switch vendors have implemented extensions that allow a single link aggregation to span across two or more of their interconnected network switches The term split trunking as used in this document refers to such crossswitch link aggregation technologies Two particular split trunking implementations referred to in this document are Nortel SMLT and Cisco stackwise cross-stack EtherChannel This document describes how HP Auto Port Aggregation (APA) can support the Cisco cross-stack EtherChannel or Nortel Split Multi-Link Trunking (SMLT) technologies This document is relevant for users of APA link aggregations only It has no relevance for users of APA LAN Monitor failover groups Definition of Split Trunking Split trunking is a link aggregation whose link partners reside on two or more switches Traffic must be able to be moved from one switch to another in case one switch fails Benefits of Split Trunks Split trunks improve the availability of a network configuration using link aggregations by eliminating the switch as a single point of failure (SPOF) If a switch fails, traffic on the link aggregation continues on the remaining switches Figures 1 and 2 show this concept In Figure 1, the physical links of the link aggregation lan900 is connected to one switch If the switch fails, the link aggregate becomes unusable 2

3 Figure 1 Link aggregate with one switch Switch lan900 HP-UX Server One way to guard against switch failure is to divide the four physical links used for the link aggregation, lan900, into two link aggregations of two ports each In Figure 2, each link aggregation is connected to a switch (lan901 and lan902) The two switches are connected to each other The link aggregates lan901 and lan902 form a failover group, lan900, with lan901 serving as the primary port When switch 1 fails, the primary port goes down and lan902 takes over 3

4 Figure 2 Failover group with redundant switches Switch #2 Switch #1 Link Aggregate lan902 (Standby) Link Aggregate lan901 (Primary) Failover Group lan900 HP-UX Server The main drawback of this configuration is that only half of the physical links are used for traffic, while the other half are always on standby Thus the bandwidth is one-half that of lan900 in Figure 1 under normal conditions With the split trunk configuration shown in Figure 3, all physical links of the link aggregate lan900 are connected to two switches participating in a stack Unlike Figure 2, all physical links participate in traffic The link aggregation bandwidth is reduced only when a member switch in the stack fails Maximum bandwidth is the same as lan900 in Figure 1 under normal conditions 4

5 Figure 3 Split trunk with stacked switches Stacked Switch #1 Stacked Switch #2 lan900 HP-UX Server 5

6 APA Split Trunking Support The example in this paper was run on an HP-UX 11i v3 system, using the J4240AA Auto-Port Aggregation product from the December 2007 AR release (version B113110) This version of APA will also provide support for split trunks on the following versions of HP-UX: 11i v3: version B or greater 11i v2: version B (PHNE_36403) or greater, Sept 2007 Application Release or later 11i v1: version B (PHNE_36483) or greater, Sept 2007 Application Release or later Split Trunk Support on Switches As described in the introduction of this document, HP APA has been verified to work with split trunking on Cisco and Nortel switches You can configure Cisco switches as a stack of switches (StackWise switch stacking) that then operate like a single switch With Cisco StackWise switch stacking, you can use both manual mode and LACP mode link aggregation on stacked switches PAgP is not supported by Cisco on stacked switches On Nortel switches, split trunking is supported using the SMLT (Split Multi-Link Trunking) features Only LACP mode is supported HP APA supports Nortel SMLT and the Cisco StackWise cross-stack EtherChannels The configuration examples are performed on the Nortel 6000 Passport switches and the Cisco 3750 switches When to Use Split Trunking If you want protection against switch failures when using link aggregates, you must set up a failover group consisting of two or more link aggregates, with ports within each link aggregate connected to a single switch The switches are then connected to each other (see Figure 2) As described earlier, the disadvantage with this configuration is that the link aggregation serving as the standby port is not carrying traffic during normal conditions, reducing the maximum available bandwidth capability Split trunking support offers several advantages over the Figure 2 configuration (failover-group of linkaggregates) First, only the link aggregate needs to be created; the configuration task is simpler Second, the split trunking solution provides a highly available and active-active failover solution You can fully employ the bandwidth provided by the ports used in the link aggregation for normal traffic all the time Bandwidth capacity is reduced only in the case of switch failure With priority or cost based failover groups, less than the full bandwidth capacity can be utilized at any one time The remainder is idling, held in reserve while waiting for the primary link-aggregate to fail For split trunks, Link Aggregation Control Protocol (LACP) link aggregates are preferred over the Manual mode link aggregates Manual mode link aggregates might not remove ports connected to failed switches As a result, traffic might still go to these ports, causing unexplained traffic losses On the other hand, with a LACP link aggregate, APA removes ports connected to the failed switches from the link aggregate, which eliminates the possibility of traffic losses 6

7 Examples The following software and hardware components were used to produce the examples in this section: HPUX 11iv3 system running APA 11iv3 December 2007 release (AR0712) Cisco Switch Model 3750G-16TD with software version SEE4 Nortel Switch Passport 8006 (software release 37130) Nortel Switch Passport 8010 (software release 37130) Setting up Split Trunks on Cisco Switches Split trunks (called cross-stack EtherChannels in Cisco documentation), are supported only on the Cisco 3750 series switches According to the Cisco 3750 configuration guide, cross-stack PAgP EtherChannels are not supported Manual and LACP mode cross-stack EtherChannels are supported To set up a switch stack, you must connect the 3750 switches to each other in a ring configuration using cables connected to the Stackwise ports on the back of the switch For information and setup instructions, see the Cisco 3750 switch configuration guide After the switch stacking is enabled on all the member switches in the stack, you can view the switch ports of all stack members from the master switch In essence, the switch stack behaves like one switch The configuration of a cross-stack EtherChannel is no different from setting up an EtherChannel on a single switch A cross-stack EtherChannel consists of switch ports on more than one switch See the configuration guide for the Cisco 3750 switch on configuring manual and LACP type EtherChannels On the HP-UX server side, use the lanadmin or nwmgr commands to create a Manual or LACP mode link-aggregation as usual For HP-UX 11i v3, use either the nwmgr or lanadmin commands to do the configuration For HP_UX 11i v2 or 11i v1, use lanadmin Example: Creating a four-port cross-stack LACP EtherChannel in active mode in a two-switch stack, two ports per switch This example creates an LACP EtherChannel using four gigabit switch ports in a two-switch stack The port mode for LACP is either active or passive The port numbers are 13 and 14 on each switch On the server side, ports 3, 4, 6, and 7 are connected to switch ports Gi1/0/13, Gi1/0/14, Gi2/0/13, and Gi2/0/14, respectively Ports Gi1/0/13 and Gi1/0/14 are on switch 1; Gi2/0/13 and Gi2/0/14 are on switch 2 On the master switch (switch 1), define the LACP EtherChannel as follows: Switch> enable Switch#config terminal Switch(config)#interface range Gi1/0/13-14 Switch(config-if-range)#switchport mode access Switch(config-if-range)#channel-group 25 mode active Switch(config-if-range)#exit Switch(config)# Switch(config)#interface range Gi2/0/13-14 Switch(config-if-range)#switchport mode access Switch(config-if-range)#channel-group 25 mode active Switch(config-if-range)#end Switch# This creates an EtherChannel with the LACP operational key value of 25 The ports actively send out LACP PDUs to their link partners On the HP-UX server, create LACP link aggregate 901 (key=901) using ports 3, 4, 6, and 7 with the following APA lanadmin commands: 7

8 # lanadmin -X -k # lanadmin -X -k # lanadmin -X -k # lanadmin -X -k # lanadmin -X -k # lanadmin -X -p 3 LACP_AUTO 900 # lanadmin -X -p 4 LACP_AUTO 900 # lanadmin -X -p 6 LACP_AUTO 900 # lanadmin -X -p 7 LACP_AUTO 900 Verify the EtherChannel configuration on the switch as follows: Switch> enable Switch# Switch#show etherchannel 25 port-channel Port-channels in the group: Port-channel: Po25 (Primary Aggregator) Age of the Port-channel = 01d:05h:36m:10s Logical slot/port = 10/25 Number of ports = 4 HotStandBy port = null Port state = Port-channel Ag-Inuse Protocol = LACP Ports in the Port-channel: Index Load Port EC state No of bits Gi1/0/13 Active Gi1/0/14 Active Gi2/0/13 Active Gi2/0/14 Active 0 Time since last port bundled: 00d:00h:02m:27s Gi2/0/14 Time since last port Un-bundled: 00d:01h:38m:55s Gi2/0/14 Switch# Verify the LACP link aggregation on the server Ports 3, 4, 6, and 7 are in LACP link aggregation 901 Enter the following APA lanadmin command: # lanadmin -x -i 901 Link Aggregate PPA # : 901 Link Aggregation Mode : LACP_AUTO Load Balance Mode : MAC Address based (LB_MAC) Active Ports PPA # : Port(s) not ready : NONE # Example: Setting up a cross stack Manual mode link aggregation If you want to set up a Manual mode link aggregation instead of the LACP link aggregation, use the same command to create this trunk on the switch Only the mode option is different In the LACP link aggregation, the mode is active or passive For Manual mode aggregation, the mode value is on On the master switch (switch 1), define the Manual mode EtherChannel as follows: Switch> enable Switch#config terminal Switch(config)#interface range Gi1/0/13-14 Switch(config-if-range)#switchport mode access 8

9 Switch(config-if-range)#channel-group 25 mode on Switch(config-if-range)#exit Switch(config)# Switch(config)#interface range Gi2/0/13-14 Switch(config-if-range)#switchport mode access Switch(config-if-range)#channel-group 25 mode on Switch(config-if-range)#end Switch# On the server side, create the manual link aggregation lan900 on HP-UX 11i v3 using nwmgr as follows: # nwmgr a A mode=manual A links=3,4,6,7 c lan900 Clearing the LACP link aggregate on the switch side To delete the link aggregation, disable the LACP on all the ports used by the EtherChannel This is done by setting the channel-group mode back to the default value as follows: Switch> enable Switch#config terminal Switch(config)#interface range Gi1/0/13-14 Switch(config-if-range)#default switchport mode Switch(config-if-range)#no channel-group Switch(config-if-range)#exit Switch(config)# Switch(config)#interface range Gi2/0/13 14 Switch(config-if-range)#default switchport mode Switch(config-if-range)#no channel-group Switch(config-if-range)#end Switch# On the server side, enter: # lanadmin X c 901 Setting up Split Trunks on Nortel Switches To create a split trunk (called a Split Multi-Link Trunk (SMLT) in the Nortel documentation), you must configure all of the switches used by the LACP trunk with an interswitch trunk (IST) Having configured the IST, the split multilink trunk is configured By definition, two switches are used in the split trunk SMLT are supported on the Nortel 8000 Passport switches Example: Creating a four-port LACP SMLT trunk This example creates an LACP SMLT using four 100 Base-T ports connected on two Nortel 8600 Passport switches Two of the four ports are connected to switch 1 at ports 2/31 and 2/32 The other two ports are connected to switch 2 also at ports 2/31 and 2/32 On the server side, switch 1 port 2/31 is connected to lan10, switch 1 port 2/32 to lan9, switch 2 port 2/31 to lan12, and switch 2 port 2/32 to lan11 Four ports per switch are used for the ISTs at ports 3/6, 3/7, 4/6, and 4/7 on each switch In the following example, the vlan 1900 is used to pass the LACP protocol PDUs between the two switches Step 1: Create the IST on both switches Set up the IST so that LACP protocol PDUs can be exchanged between the two switches Create the IST on switch 1 as follows: 9

10 Switch1# conf vlan 1900 create byport 1 Switch1# conf mlt 21 delete Switch1# conf mlt 21 create Switch1# conf mlt 21 add ports 3/6-3/7,4/6-4/7 Switch1# conf mlt 21 perform-tagging enable Switch1# conf mlt 21 add vlan 1900 Switch1# conf vlan 1900 ip create 1112/30 Switch1# conf mlt 21 ist create ip 1111 vlan-id 1900 Now create the IST on Switch 2 as follows: Switch2# conf vlan 1900 create byport 1 Switch2# conf mlt 21 delete Switch2# conf mlt 21 create Switch2# conf mlt 21 add ports 3/6-3/7,4/6-4/7 Switch2# conf mlt 21 perform-tagging enable Switch2# conf mlt 21 add vlan 1900 Switch2# conf vlan 1900 ip create 1112/30 Switch2# conf mlt 21 ist create ip 1111 vlan-id 1900 Note: The vlan 1900 on switch 1 and switch 2 have different IP addresses To verify the IST configuration on each switch, enter the following command on each switch to display the multilink trunk (MLT) information: # show mlt info ================================================================================ Mlt Info ================================================================================ PORT SVLAN MLT MLT PORT VLAN MLTID IFINDEX NAME TYPE TYPE ADMIN CURRENT MEMBERS IDS p18_bl1_mlt trunk normal norm norm 1/32,1/ SMLT-22 access normal smlt norm 1/ Aggregate_3 access normal norm norm MLT-44 access normal norm norm 1/7-1/ SMLT-11 access normal smlt norm 1/ MLT-13 access normal norm norm 3/8,4/ SMLT-14 access normal smlt norm MLT-21 trunk normal ist ist 3/6-3/7,4/6-4/ Aggregate_Gig access normal smlt norm 3/ MLT-25 access normal smlt norm MULTICAST DESIGNATED LACP LACP MLTID IFINDEX DISTRIBUTION NT-STG PORTS ADMIN OPER disable enable 1/32 disable down disable disable 1/29 disable down disable disable null enable down disable enable 1/7 disable down disable disable 1/16 enable down disable disable 3/8 disable down disable disable null disable down disable enable 3/6 disable down disable disable 3/2 enable up disable disable null enable down Step 2: Create the SMLT on both switches The LACP link aggregation on the switch side uses the mlt 31 After creating the MLT, create the SMLT using the id 31 For simplicity, the key of the LACP aggregation key is also 31 To create the SMLT and enable LACP on it using key=31, enter the following commands on each switch: # conf mlt 31 create # conf mlt 31 lacp key 31 # conf mlt 31 lacp enable 10

11 # conf mlt 31 smlt create smlt-id 31 Step 3: Enable LACP on all the switch ports in the aggregation Now that the SMLT has been defined on both switches, LACP is enabled on the switch ports Because you are using switch ports 2/31 and 2/32 on both switches, the commands to enable LACP on the switch ports are identical for both switches as follows: Switch1# conf ether 2/31-2/32 lacp key 31 Switch2# conf ether 2/31-2/32 lacp aggregation true Switch3# conf ether 2/31-2/32 lacp enable Step 4: On the HP-UX 11i v3 server side, create the LACP link aggregation lan900 using ports lan9, lan10, lan11, and lan12 using key=900 as follows: # nwmgr s A key=900 c lan900 # nwmgr s S apa A key=900,mode=lacp_auto c lan9 # nwmgr s S apa A key=900,mode=lacp_auto c lan10 # nwmgr s S apa A key=900,mode=lacp_auto c lan11 # nwmgr s S apa A key=900,mode=lacp_auto c lan12 For information about the nwmgr APA commands, see the APA Administrators Guide for HP-UX 11i v3 To verify the link aggregation creation on switch 1, enter: Switch1# show mlt info ================================================================================ Mlt Info ================================================================================ PORT SVLAN MLT MLT PORT VLAN MLTID IFINDEX NAME TYPE TYPE ADMIN CURRENT MEMBERS IDS p18_bl1_mlt trunk normal norm norm 1/32,1/ MLT-21 trunk normal ist ist 3/6-3/7,4/6-4/ MLT-31 access normal smlt smlt 2/31-2/32 1 To verify the link aggregation creation on switch 2, enter: Switch2# show mlt info ================================================================================ Mlt Info ================================================================================ PORT SVLAN MLT MLT PORT VLAN MLTID IFINDEX NAME TYPE TYPE ADMIN CURRENT MEMBERS IDS p18_bk1_mlt trunk normal norm norm 1/32,1/ MLT-21 trunk normal ist ist 3/6-3/7,4/6-4/ MLT-31 access normal smlt smlt 2/31-2/32 1 To verify the LACP link aggregation on the server, enter: 11

12 # nwmgr -g -S apa Class Mode Load Speed- Membership Instance Balancing Duplex ======== =========== ========= ==================== =========================== lan900 LACP_AUTO LB_MAC 400 Mbps Full Duplex 9,10,11,12 lan901 Not_Enabled LB_MAC 0 Mbps - lan902 Not_Enabled LB_MAC 0 Mbps - lan903 Not_Enabled LB_MAC 0 Mbps - lan904 Not_Enabled LB_MAC 0 Mbps - # Removing the LACP Aggregation on the Switches To remove the LACP aggregation on the switches, disable LACP on all the ports added to the SMLT So on each switch, disable LACP on ports 2/31 and 2/32 Then delete the MLT-31 So on each switch, enter the following commands: # conf ether 2/31-2/32 lacp disable # conf mlt 31 delete Removing the IST on the Switches In order to remove an IST, you must first disable it Then, delete the IST from the MLT and remove the MLT Enter the following commands on each switch: # conf mlt 21 ist disable # conf mlt 21 ist delete # conf mlt 21 delete Example: Create a SMLT Trunk in Manual Mode To create an SMLT trunk running in Manual mode using the same ports as the previous example, you must first create the IST See the example on creating the LACP SMLT link aggregation to do that Then, create the SMLT trunk by entering the following commands on each switch: Switch# conf mlt 31 create Switch# conf mlt 31 add ports 2/31-2/32 Switch# conf mlt 31 smlt create smlt-id 31 On the server side, create the Manual mode link aggregation using the nwmgr command (available only on HP-UX 11i v3) as follows: # nwmgr a A mode=manual A links=9,10,11,12 c lan900 Conclusion Currently both Nortel SMLT and Cisco switches support LACP and Manual type split trunks When you can use switches configured for SMLT or stacking, HP recommends that you use a split LACP link aggregation to provide a highly available link aggregation In addition, this solution is also an active-active failover solution as each member ports bandwidth can carry traffic When switch failure occurs, the link aggregation remains available but its bandwidth capability is reduced A split LACP link aggregation is preferred over a split Manual mode link aggregation The Manual mode link aggregations cannot handle switch failures As a result, ports connected to the bad switch might still be part of the link aggregation This can cause traffic to be transmitted on the bad switch ports, and might be dropped as a result With the LACP protocol, ports connected to failed switches are dropped from the LACP link aggregations Consequently, traffic losses are eliminated If you do not have switches that can be configured to utilize SMLT or cross-stack EtherChannels, you can still have the capability for a highly available network link by using a failover group of link 12

13 aggregates (as shown in Figure 2), with the drawback being that some of the full bandwidth capacity has to be left unused in case of primary link failure 13

14 For more information On the HP Auto Port Aggregation product: HP Auto Port Aggregation Administrator's Guide, December On the Usage of Cisco 3750 Switches: Catalyst 3750 Switch Software Configuration Guide, Cisco IOS Release 122(40)SE Part Number OL August figuration/guide/3750scgpdf On SMLT on Nortel Ethernet Routing Switches: Nortel Networks, Link Aggregation Control Protocol (LACP) 8023ad and VLACP for ES and ERS Technical Configuration Guide September P_for_ES_and_ERS_TCG_J_Vant_Erve_NN pdf 2009 Hewlett-Packard Development Company, LP The information contained herein is subject to change without notice The only warranties for HP products and services are set forth in the express warranty statements accompanying such products and services Nothing herein should be construed as constituting an additional warranty HP shall not be liable for technical or editorial errors or omissions contained herein Cisco is a trademark of Cisco Systems, Inc Nortel is a trademark of Nortel Networks J , January 2009