Brocade Multi-Service IronWare Switching Configuration Guide (Supporting R05.6.00) - Manual (Page 630)

600 Multi-Service IronWare Switching Configuration Guide
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About Multi-Chassis Trunk (MCT)
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STP
• The STP algorithm has been modified such that ICL never goes to blocking. ICL guard
mechanism ensures that if ICL is going in blocking state then the port on which the superior
BPDUs are being received is moved to BLOCKING state and ICL guard timer starts running on
it. This timer runs as long as Superior BPDUs are received on this interface. As long as this
timer runs on an interface the Superior BPDUs are dropped.
• The modified STP algorithm also ensures that the CCEP interface state on both the MCT peers
is same.
• The CCEP STP state information between MCT peers is synchronized using messages that are
sent over CCP.
• Only one of the MCT peers send BPDUs towards the MCT Client. It is decided by whosoever is
the designated bridge on the ICL.
• New STP States:
• BLK_BY_ICL state indicates that the superior BPDUs were being received on this interface
which could have led to BLOCKING of ICL interface, due to which ICL port guard
mechanism has been triggered on this port.
• FWD_BY_MCT state indicates that the MCT peer has set the CCEP state to forwarding.
• BLK_BY_MCT state indicates that the MCT peer has set the CCEP state to blocking.
Dynamic Layer 3 routing over MCT
When configuring dynamic L3 protocol support over MCT, you should consider the following.
• L3 Protocols IS-ISv4, IS-ISv6, BGP4, BGPv6, OSPFv2, OSPFv3, RIP, and RIPng are supported.
• CCEP and CEP are on different L3 networks.
• Any of the L3 protocol can be configured on the CCEP ports and CEP ports.
• An ICL interface can not be configured with L3 routing protocols.
• A CEP Network is reachable via MCT nodes even when the CCEP is down on one of the peers ,
the traffic will take redundant path via MCT.
• Active and Passive L3 routing protocols interfaces are supported.
MCT feature interaction
Use the following feature matrix when configuring MCT:
TABLE 79 MCT feature interaction matrix
Supported Not Supported
LACP on both ICL and CCEP. MSTP, VSRP, and PIM
PIM is supported over ICL and CCEP links
VRRP on CCEP ports. ESI VLANs on CCEP or ICL ports.
MRP and MRP II supported with the restriction that
ICL port cannot be the secondary port of the MRP
ring. GRE is not supported on the ICL ve interfaces
BGP, IS-IS, and OSPF on on CCEP ports.
802.1ad on CCEP or ICL ports. DAI on the CCEP ports.