Split Trunking Support with HP Auto Port Aggregation Overview............................................................................................................................................ 2 When to Use Split Trunking ............................................................................................................... 6 Examples ............................................................................................................................................
Overview The IEEE 802.3ad 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.
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.
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.
Figure 3.
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 B.11.31.10). This version of APA will also provide support for split trunks on the following versions of HP-UX: • 11i v3: version B.11.31.02 or greater • 11i v2: version B.11.23.25 (PHNE_36403) or greater, Sept. 2007 Application Release or later • 11i v1: version B.11.11.25 (PHNE_36483) or greater, Sept.
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 12.2.25-SEE4. • Nortel Switch Passport 8006 (software release 3.7.13.0) • Nortel Switch Passport 8010 (software release 3.7.13.
# # # # # # # # # lanadmin lanadmin lanadmin lanadmin lanadmin lanadmin lanadmin lanadmin lanadmin -X -X -X -X -X -X -X -X -X -k -k -k -k -k -p -p -p -p 901 901 900 3 901 900 4 901 900 6 901 900 7 901 900 3 LACP_AUTO 4 LACP_AUTO 6 LACP_AUTO 7 LACP_AUTO 900 900 900 900 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) -----------Ag
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,
Switch1# Switch1# Switch1# Switch1# Switch1# Switch1# Switch1# Switch1# conf conf conf conf conf conf conf conf vlan 1900 create byport 1 mlt 21 delete mlt 21 create mlt 21 add ports 3/6-3/7,4/6-4/7 mlt 21 perform-tagging enable mlt 21 add vlan 1900 vlan 1900 ip create 1.1.1.2/30 mlt 21 ist create ip 1.1.1.
# 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.
# nwmgr -g -S apa Class Mode Instance ======== =========== lan900 LACP_AUTO lan901 Not_Enabled lan902 Not_Enabled lan903 Not_Enabled lan904 Not_Enabled # Load Balancing ========= LB_MAC LB_MAC LB_MAC LB_MAC LB_MAC SpeedMembership Duplex ==================== =========================== 400 Mbps Full Duplex 9,10,11,12 0 Mbps 0 Mbps 0 Mbps 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.
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.
For more information On the HP Auto Port Aggregation product: HP Auto Port Aggregation Administrator's Guide, December 2007 http://docs.hp.com/en/J4240-90041/J4240-90041.pdf On the Usage of Cisco 3750 Switches: Catalyst 3750 Switch Software Configuration Guide, Cisco IOS Release 12.2(40)SE Part Number OL-8550-04. August 2007. http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/software/release/12.2_40_se/con figuration/guide/3750SCG.
