Configuration Guide

Table Of Contents
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October 2021
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3.4 SPB IP Shortcuts
Figure 5: SPB IP Shortcuts
IP shortcuts allow routing between VLANs in the global routing table/network routing engine
(GRT/NRE/VRF-0). No ISID configuration is used. IP is enabled on the B-VLAN IS-IS instance on the BEB
switches. This provides normal IP forwarding between BEB sites over an IS-IS backbone.
In summary:
IP must be enabled on IS-IS where the IS-IS source address, which must be configured, is a
circuitless/loopback IP address
o
The IS-IS source address is automatically injected into IS-IS
IS-IS redistribution of direct (or OSPF, RIP, Static, BGP…) IP routes may be enabled as a simple
mechanism to forward those networks between BEB neighbors
o
This will inject all direct (or OSPF, RIP, Static, BGP…) IP routes into IS-IS
o
In a SMLT cluster, in the case of direct IP route redistribution, a route policy (CLI) or route-
map (ACLI) must be configured to match the IST IP subnet to prevent it from being
advertised
The Extended IP Reachability TLV 135 is used to distribute IP reachability between IS-IS peers