Configuration Guide

Table Of Contents
20.1.18IP Shortcuts – redistribution of ISIS and OSPF
©2021 Extreme Networks, Inc. All rights reserved
October 2021
121
This section goes over several methods on how to redistribute ISIS into OSPF and vise-versa.
ERS 8000 – redistribution of ISIS into OSPF and vise-versa
Please note the following:
The ERS 8800 does not support ISIS accept policies
o
There is no way to prevent one border router from accepting ISIS routes from the other
border router
o
The solution is to make OSPF preferred over ISIS by assigning ISIS a higher route
preference over OSPF
We can now use OSPF accept policies to prevent one border router from
accepting OSPF external routes from another
configure terminal
no ip alternative-route
ip route preference protocol spbm-level1 130
route-map "reject" 1
no permit
enable
exit
router ospf
as-boundary-router enable
accept adv-rtr 10.1.1.1 enable route-policy
"reject"
redistribute isis
redistribute isis enable
exit
ip ospf apply accept adv-rtr 10.1.1.1
router isis
redistribute ospf
redistribute ospf enable
exit
isis apply redistribute ospf
ip ospf apply redistribute isis
configure terminal
no ip alternative-route
ip route preference protocol spbm-level1 130
route-map "reject" 1
no permit
enable
exit
router ospf
as-boundary-router enable
accept adv-rtr 10.1.1.2 enable route-policy
"reject"
redistribute isis
redistribute isis enable
exit
ip ospf apply accept adv-rtr 10.1.1.2
router isis
redistribute ospf
redistribute ospf enable
exit
isis apply redistribute ospf
ip ospf apply redistribute isis