Redistribution Notes – Tagging

• Tagging provides a way to mark common or similar routes to manipulate later.
• In redistribution scenarios with mutual redistribution on two different routers, any routes that gets redistributed from one route process to another are tagged.
  • When the other router sees those tags on the route, that route to keep from adding non-optimal routes to its routing table.
• Tags can also be used to do other manipulation such as setting higher metrics or changing ADs.

OSPF

R102#show run ... router ospf 1 log-adjacency-changes redistribute connected subnets route-map SETTAG network 192.0.2.0 0.0.0.255 area 0 ! route-map SETTAG permit 100 set tag 55555 ... R101#sh ip route 10.0.0.2 Routing entry for 10.0.0.0/24 Known via "ospf 1", distance 110, metric 20 Tag <strong>55555</strong>, type extern 2, forward metric 10 Last update from 192.0.2.102 on Ethernet0/0, 00:00:13 ago Routing Descriptor Blocks: * 192.0.2.102, from 192.0.2.102, 00:00:13 ago, via Ethernet0/0 Route metric is 20, traffic share count is 1 Route tag <strong>55555</strong>

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R102#show run ... router ospf 1 log-adjacency-changes redistribute connected subnets route-map SETTAG network 192.0.2.0 0.0.0.255 area 0 ! route-map SETTAG permit 100 set tag 55555 ...   R101#sh ip route 10.0.0.2 Routing entry for 10.0.0.0/24 Known via "ospf 1", distance 110, metric 20 Tag <strong>55555</strong>, type extern 2, forward metric 10 Last update from 192.0.2.102 on Ethernet0/0, 00:00:13 ago Routing Descriptor Blocks: * 192.0.2.102, from 192.0.2.102, 00:00:13 ago, via Ethernet0/0 Route metric is 20, traffic share count is 1 Route tag <strong>55555</strong>

EIGRP

R102#sh run ... router eigrp 1 network 192.0.2.0 redistribute connected route-map SETTAG no auto-summary ! route-map SETTAG permit 100 set tag 55555 ... R101#sh ip route 10.0.0.2 Routing entry for 10.0.0.0/24 Known via "eigrp 1", distance 170, metric 409600 Tag <strong>55555</strong>, type external Redistributing via eigrp 1 Last update from 192.0.2.102 on Ethernet0/0, 00:00:14 ago Routing Descriptor Blocks: * 192.0.2.102, from 192.0.2.102, 00:00:14 ago, via Ethernet0/0 Route metric is 409600, traffic share count is 1 Total delay is 6000 microseconds, minimum bandwidth is 10000 Kbit Reliability 255/255, minimum MTU 1500 bytes Loading 1/255, Hops 1 Route tag <strong>55555</strong>

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R102#sh run ... router eigrp 1 network 192.0.2.0 redistribute connected route-map SETTAG no auto-summary ! route-map SETTAG permit 100 set tag 55555 ...   R101#sh ip route 10.0.0.2 Routing entry for 10.0.0.0/24   Known via "eigrp 1", distance 170, metric 409600   Tag <strong>55555</strong>, type external   Redistributing via eigrp 1   Last update from 192.0.2.102 on Ethernet0/0, 00:00:14 ago   Routing Descriptor Blocks:   * 192.0.2.102, from 192.0.2.102, 00:00:14 ago, via Ethernet0/0       Route metric is 409600, traffic share count is 1       Total delay is 6000 microseconds, minimum bandwidth is 10000 Kbit       Reliability 255/255, minimum MTU 1500 bytes       Loading 1/255, Hops 1       Route tag <strong>55555</strong>

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Corrections are encouraged.

Aaron Conaway

I shake my head around sometimes and see what falls out. That's what lands on these pages. If you have any questions, the best way to contact me is through Twitter at @aconaway.

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