BROCADE IP PRIMER

Chapter 7: Link Aggregation (Trunks)A port defined as LACP can be either active or passive. If a port is active, it cansend and receive LACPDUs with the other side of the link. This enables theswitch to negotiate and configure the trunk. If a port is in passive mode, theport may receive and respond to LACPDUs, but it may not initiate the negotiationprocess.Configuring TrunksThere are a few rules to be aware of when configuring trunks.Rule #1. Generally speaking, if you are dealing with a stackable switch, youcan only configure a two- or four-port trunk. On chassis switches, you can configurea two-, four-, or eight-port trunk. This rule is not hard and fast. Consultthe Brocade web site (http://www.brocade.com/) for your specific model.Rule #2. Your trunk links must be contiguous. You cannot create a trunk containing,say, ethernet 1, ethernet 6, ethernet 11, and ethernet 23. Given thisexample, if you wanted to configure a four-port trunk starting with port 1, youmust configure the trunk to include ethernet 1, ethernet 2, ethernet 3, andethernet 4.Rule #3. For a two-port trunk, you must start your trunk on an odd-numberedport. For example, you can trunk ethernet 1 and ethernet 2, but you cannottrunk ethernet 2 and ethernet 3.Rule #4. For a four-port trunk, you must start your trunk on ethernet 1, 5, 9,13, 17, etc. You cannot start your trunk on, say, ethernet 3. It's an odd number,but it's not within the four-port divisor (starting with port 1). If you're still confusedby this rule, a good rule to remember is to take the last port of yourproposed four-port trunk-if you can divide that port number by four evenly, it isa valid trunk.Rule #5. Similar to Rule #4, except now we're talking about eight-port trunks.These trunks must start on ethernet 1, 9, 17, etc. A similar rule applies (as inRule #4). If you can divide the last port number in your proposed trunk by eightevenly, it is a valid trunk.Rule #6. The ports in the trunk must have the same tag type (tagged/untagged), they must be in the same VLAN, they must be the same speed andduplex, and they must be the same Quality of Service (QoS) priority.Rule #7. For chassis switches, you can create a four- or eight-port trunk thatspans neighboring blades.For this to work, the ports on either blade have to align. For example, e 1/1 to1/4 and e 2/1 to 2/4 may be trunked in an eight-port trunk. You cannot trunke 1/1 to 1/4 and e 2/5 to 2/8 in a single eight-port trunk. Notice also that Imentioned neighboring blades. You cannot span the trunk from slot 1 to, say,slot 4. It must be slot 1 to slot 2. This brings up another good point, you muststart the multi-blade trunk on an odd-numbered slot. You can trunk from slot 1to slot 2, but you cannot trunk from slot 2 to slot 3.162 Brocade IP Primer