Design Reference

• routing prefix of 2003::/64
As a shorthand, the last two items in the preceding list are referred to as 2003::1/64.
R2 uses the following configuration:
• link-local address of fe80::1
• global unicast address and routing prefix if routing prefix of 2003::2/64.
Host H1 sends IPv6 traffic destined to VLAN 1 to the MAC address for R1. H2 sends traffic to the
MAC address for R2. After an IPv6 packet destined to the MAC address of R1 is received at R2 on
its SMLT links (the expected MLT behavior), R2 performs IPv6 forwarding on the packet and does
not bridge it over the vIST. The same behavior occurs on R1.
At startup, R1 and R2 use the vIST link to exchange full configuration information that includes the
MAC address for the IPv6 interfaces that reside on SMLT VLAN 3.
After R2 detects that the RSMLT in R1 transitions to the down state (for example, if R1 itself is
down, the SMLT links are down, or the vIST link is down) R2 takes over IPv6 termination and IPv6
neighbor discovery on behalf of the IPv6 SMLT interface on R1. The following list shows the order of
action in this situation:
1. After R2 detects the event, it transmits an unsolicited IPv6 neighbor advertisement for each
IPv6 address configured on the SMLT link of R1 using the R1 MAC address (fe80::1 and
2003::1 in this example).
2. R2 transmits an unsolicited router advertisement for each of the R1 routing prefixes (unless
the prefixes are configured as not advertised).
3. R2 responds to neighbor solicitations and, if the configuration allows, router advertisements
on behalf of R1.
4. R2 terminates IPv6 traffic (such as ping requests) destined to the R1 SMLT IPv6 addresses.
After R1 RSMLT transitions back into the up state and the hold-down timer expires, R1 resumes
IPv6 forwarding and R2 ceases to terminate IPv6 traffic on behalf of R1.
IPv6 provides a rich set of configuration options to advertise IPv6 routing prefixes (equivalent to
IPv4 subnets) and to configure hosts on a link. You can configure a prefix to be or not be advertised,
and to carry various flags or lifetime values. These parameters affect how hosts can automatically
configure their IPv6 addresses and select their default routers. Most relevant from the RSMLT
perspective is that an RSMLT node fully impersonates the peer IPv6 configuration and behavior on
the SMLT link. The preceding network example illustrates one of the many possible deployment
scenarios for IPv6 routers and hosts on a VLAN.
RSMLT provides both router failover and link failover. For example, if the SMLT link between R2
and R4 is broken, the traffic fails over to R1 as well.
Related Links
Layer 3 switch clustering and RSMLT on page 54
Layer 3 switch clustering and RSMLT
60 Network Design Reference for Avaya VSP 4000 Series June 2015
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