Dell S4048T, Руководство по настройке

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The multi-topology ID is shown in the first octet of the IS-IS packet. Certain MT topologies are assigned to
serve predetermined purposes:
• MT ID #0: Equivalent to the “standard” topology.
• MT ID #1: Reserved for IPv4 in-band management purposes.
• MT ID #2: Reserved for IPv6 routing topology.
• MT ID #3: Reserved for IPv4 multicast routing topology.
• MT ID #4: Reserved for IPv6 multicast routing topology.
• MT ID #5: Reserved for IPv6 in-band management purposes.
Transition Mode
All routers in the area or domain must use the same type of IPv6 support, either single-topology or multi-
topology. A router operating in multi-topology mode does not recognize the ability of the single-topology
mode router to support IPv6 traffic, which leads to holes in the IPv6 topology.
While in Transition mode, both types of TLVs (single-topology and multi-topology) are sent in LSPs for all
configured IPv6 addresses, but the router continues to operate in single-topology mode (that is, the
topological restrictions of the single-topology mode remain in effect). Transition mode stops after all routers
in the area or domain have been upgraded to support multi-topology IPv6. After all routers in the area or
domain are operating in multi-topology IPv6 mode, the topological restrictions of single-topology mode are
no longer in effect.
Interface Support
MT IS-IS is supported on physical Ethernet interfaces, physical synchronous optical network technologies
(SONET) interfaces, port-channel interfaces (static and dynamic using LACP), and virtual local area network
(VLAN) interfaces.
Adjacencies
Adjacencies on point-to-point interfaces are formed as usual, where IS-IS routers do not implement MT
extensions.
If a local router does not participate in certain MTs, it does not advertise those MT IDs in its IS-IS hellos (IIHs)
and so does not include that neighbor within its LSPs. If an MT ID is not detected in the remote side’s IIHs, the
local router does not include that neighbor within its LSPs. The local router does not form an adjacency if
both routers do not have at least one common MT over the interface.
Graceful Restart
Graceful restart is a protocol-based mechanism that preserves the forwarding table of the restarting router
and its neighbors for a specified period to minimize the loss of packets. A graceful-restart router does not
immediately assume that a neighbor is permanently down and so does not trigger a topology change.
Normally, when an IS-IS router is restarted, temporary disruption of routing occurs due to events in both the
restarting router and the neighbors of the restarting router. When a router goes down without a graceful
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