Brocade Multi-Service IronWare Routing Configuration Guide (Supporting R05.6.00) - Manual (Page 772)

744 Multi-Service IronWare Routing Configuration Guide
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IPv6 IS-IS Multi-Topology
Maintaining MT adjacencies
With the extension of IPv6 IS-IS MT, the new type, length, and value (TLV) parameters are added
into the IS to IS hello (IIH) packets that advertise the topologies of the interface. In IPv6 IS-IS MT,
the router advertises its information using the new TLV parameters such as MT ID TLV, MT IS
Reachability TLV, MT Reachable IPv4 TLV, and MT Reachable IPv6 TLV. The TLVs specify the types of
data, the maximum length of the data, and the valid values for the data.
Forming adjacencies on the point-to-point interfaces
On a point-to-point interface, adjacencies are formed with IS-IS routers that do not implement MT
extensions. If two peers share at least one common topology, then an adjacency is formed between
the peers.
Forming adjacencies on the broadcast interfaces
On a broadcast interface, all the MT-enabled routers advertise their MT capability TLV in their IIH
packets. The MT-enabled IS-IS routers form adjacency with any IS-IS routers whether or not MT is
enabled. A peering MT-disabled IS-IS router does not form adjacency when NLPID TLVs do not
match.
New TLV attributes
The new TLV parameters to support the IPv6 IS-IS MT extension are MT ID TLV, MT IS Reachability
TLV, MT Reachable IPv4 TLV, and MT Reachable IPv6 TLV.
Enabling IPv6 IS-IS MT
When you enable IPv6 IS-IS MT in an area or a domain, the MT-enabled router runs IPv6 IS-IS in
multi SPF mode. You can enable IPv6 IS-IS MT transition mode in an area or a domain using the
transition option of the multi-topology command. The transition option allows the network
operating in IPv6 IS-IS single-topology support mode to continue to work while upgrading routers to
include IPv6 IS-IS MT support. When you enable transition mode, the router advertises both the
single-topology TLVs and MT TLVs.
When transition mode is not enabled, the routers operating in single-topology mode do not
establish IPv6 connectivity with the routers operating in MT mode.
To enable IPv6 IS-IS MT, enter the following command at the IPv6 unicast address family
configuration level.
Brocade(config-isis-router-ipv6u)# multi-topology
Syntax: [no] multi-topology
The [no] form of the command disables IPv6 IS-IS MT.
To enable IPv6 IS-IS MT with transition support, enter the following command at the IPv6 unicast
address family configuration level.
Brocade(config-isis-router-ipv6u)# multi-topology transition
Syntax: [no] multi-topology [transition]