So it's that time again for me to renew my Cisco Certifications. As a result, this post will be based on my preparation for the CCNP Route Exam (300-101).
In this post I will be focusing on Route Redistribution
Route Redistribution
- Used to take route learned from one routing protocol and inject it into another
- Can be done within the same protocol where different autonomous numbers are used
- must have at a minimum 1 physical interface in each domain
- Uses the "redistribute" command with options
- protocol - the source routing protocol
- process-id - for routing protocols which uses process id
- metric - include bandwidth, delay, etc
- match - matches internal OSPF routes
- tag - unitless integer to redistributed routes
- route-map - used for logic in the referenced route map
- Only information in the routing table is used
- Redistributed routes are treated as external routes
Redistributing EIGRP into OSPF and vice versa
- OSPF creates a type 5 LSA to represent each route
- Type 7 used when redistributed into a not-so-stubby area (NSSA)
- OSPF uses an integer metric
- Route filtering and route summarization can be used at the redistribution router
- when redistributing OSPF into EIGRP the metric must be set using either of:
- default-metric
- metric
- route-map
- Can use "redistribute ospf 1 metric 10000 33 255 1 1500"
- External routes are flagged with EX
- OSPF has its own default metric for redistributing EIGRP routes
- OSPF external routes are either type 1 (E1) or type 2 (E2)
- By default OSPF create type 2 (E2) when redistributing
E1 vs E2 routes
- E2 routes uses external cost only
- E1 routes uses both internal and external cost
- OSPF prefers E1 over E2 when given a prefix/length
When Route Redistribution is not possible?
- Stubby and totally stubby areas cannot do redistribute external routes
References:
CCNP official Cert Guide - CCNP Routing and Switching - Route 300-101
http://www.cisco.com/c/en/us/support/docs/ip/enhanced-interior-gateway-routing-protocol-eigrp/8606-redist.html
http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_rip/configuration/xe-3s/irr-xe-3s-book/ip6-rip-route-redist-xe.pdf
http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_rip/configuration/15-mt/irr-15-mt-book/ip6-rip-route-redist.html
No comments:
Post a Comment