It does not matter if that edge vlan is tagged over SMLT links, single attached links, or more SMLT links; what you could do with VRRP, you can do with RSMLT Edge.
RSMLT considerations with OSPF
If you run OSPF with RSMLT in a square or mesh, and a node loses the IST connection to its peer, OSPF adjacencies can be lost. In this scenario, OSPF is not guaranteed to be in a consistent state.
Border Gateway Protocol
Border Gateway Protocol (BGP) is an interdomain routing protocol that provides loop-free interdomain routing between autonomous systems (AS) or within an AS. BGP systems can exchange network layer reachability information (NLRI) with other BGP systems to construct a graph of AS connectivity. BGP uses this information to prune routing loops and enforce AS-level policy decisions. Border Gateway Protocol provides features with which you can consolidate routing information and control the flow of BGP updates.
Nortel Ethernet Routing Switch 8600 Configuration — BGP Services (NN46205-510) explains BGP features.
Bidirectional Forwarding Detection
Use Bidirectional Forwarding Detection (BFD) to provide a failure detection mechanism between two systems.
ATTENTION
The Ethernet Routing Switch 8600 supports BFD only in Ethernet Routing Switch 8600 Releases 4.1.5.9. Therefore, the material in this section only applies to these releases. Release 4.1.5.9 is a special release for use only with Carrier VoIP solutions, including Succession Communication Server 2000.
Bidirectional Forwarding Detection navigation
•
“BFD overview” (page 65)•
“BFD and RSMLT” (page 67)•
“BFD restrictions” (page 67)BFD overview
BFD is a simple Hello protocol used between two peers. In BFD, each peer system periodically transmits BFD packets to each other. If one of the systems does not receive a BFD packet after a certain period of time, the system assumes that the link or other system is down.
BFD provides low-overhead, short-duration failure detection between two systems. BFD also provides a single mechanism for connectivity detection over any media, at any protocol layer.
Because BFD sends rapid failure detection notifications to the routing protocols that run on the local system, which initiates routing table recalculations, BFD helps reduce network convergence time.
BFD supports IPv4 single-hop detection for static routes, OSPF, and BGP.
The Ethernet Routing Switch 8600 BFD implementation complies with IETF drafts draft-ietf-bfd-base-06 and draft-ietf-bfd-v4v6-1hop-06.
“Bidirectional Forwarding Detection configuration using Enterprise Device Manager” (page 395) explains BGP configuration by using Enterprise Device Manager. “Bidirectional Forwarding Detection configuration using CLI” (page 403)explains BGP configuration by using CLI.“Bidirectional Forwarding Detection configuration using NNCLI” (page 409) explains BGP configuration by using NNCLI.
BFD operation
The Ethernet Routing Switch 8600 uses one BFD session for all protocols with the same destination. For example, if a network runs OSPF and BGP across the same link with the same peer, only one BFD session is established, and BFD shares session information with both routing protocols.
You can enable BFD over data paths with specified OSPF neighbors, BGP neighbors, and static routing next-hop addresses.
The Ethernet Routing Switch 8600 supports BFD asynchronous mode, which sends BFD control packets between two systems to activate and maintain BFD neighbor sessions. To reach an agreement with its neighbor about how rapidly failure detection occurs, each system estimates how quickly it can send and receive BFD packets.
A session begins with the periodic, slow transmission of BFD Control packets. When bidirectional communication is achieved, the BFD session comes up.
After the session is up, the transmission rate of Control packets can increase to achieve detection time requirements. If Control packets are not received within the calculated detection time, the session is declared down. After a session is down, Control packet transmission returns to the slow rate.
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If a session is declared down, it cannot come back up until the remote end signals that it is down (three-way handshake). A session can be kept administratively down by configuring the state of AdminDown.
In asynchronous mode, detection time is equal to the value of DetectMult received from the remote system multiplied by the agreed transmit interval of the remote system (the greater of RequiredMinRxInterval and DesiredMinTxInterval.) DetectMult is approximately equal to the number of sequential packets that must be missed to declare a session down.
To enable BFD between two peers:
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Configure BFD on required interfaces of both peer systems.•
To start a BFD session with a next-hop device, enable BFD on the required routing protocols.•
Specify the next-hop device with which the switch initiates the BFD session.BFD requirements
BFD requires the 8692 SF/CPU with SuperMezz or 8895 SF/CPU.
BFD and RSMLT
BFD is not intended (and therefore currently not supported) to be run with RSMLT VLAN connections. For any RSMLT configurations, use VLACP for rapid peer node failure detection.
BFD restrictions
The Ethernet Routing Switch 8600 supports either 256 Static BFD, 100 OSPF BFD, or 150 BGP BFD. However, the number of BFD sessions plus the number of VLACP sessions cannot exceed 256.
The Ethernet Routing Switch 8600 does not support the following IETF BFD options:
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Echo packets•
BFD over IPv6•
Demand mode•
authenticationThe Ethernet Routing Switch 8600 supports:
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partial High Availability (HA) for BFD•
BFD on VRF0•
changing the TX or RX interval during BFD sessionATTENTION
Ethernet Routing Switch 8600 does not support BFD on a VRRP virtual interface.
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