Command "default-information originate" in isis enable L1L2 IS generates a 0.0.0.0/0 prefix in its Level-2 lsp.But what will happen if the L1L2 IS is unattached from backbone?
For example,dut2 has been set NET1 and NET2,dut1 is only set NET1,both dut1 and dut2 is configed as level-1-2 IS.dut1 and dut2 has L2 adj on lan1 and has L1 adj on lan2.dut2 has been config with "default-information originate".
dut1 will set ATT bit in his level-1 lsp,and will install a level-2 default route point to dut2.dut2 can NOT reach other area via level-2 topology,so dut2 think that it's unattached from backbone,so a level-1 default route is installed on dut2,the next-hop is dut1.Thus a route loop is created.
The only way I could think of to prevent this is to attach a route map to the default-information originate on dut2, so it only advertises a default if it can see some route it should be learning from the l2 area. Most networks I've seen use a route map to condition the advertisement of the 0/0, or redistribute it at their dmz border in some way.
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...