Hey all,
We stumbled upon two EIGRP problems today after updating our core 6500s from SXH to SXI:
1- It seems the EIGRP router id auto selection logic has changed: we have a couple of loopback interfaces configured on our cores, lo0 being our main one (10.0.0.1 on primary core, 10.0.0.2 on secondary core), and lo1 having the highest IP of all loopbacks at 10.0.0.254. On SXH, EIGRP used to select lo0's IP for router-id. Now on SXI, it selects 10.0.0.254. Reading back the docs, I do see that it says it selects the highest IP of loopback interfaces, but why the behavior change? Anyone else noticed that?
2- EIGRP in SXI now seems to add an originating router field to internal route updates (instead of only external routes).
Under SXI:
CORE1#show ip eigrp topo 10.0.0.2/32
EIGRP-IPv4 Topology Entry for AS(1)/ID(10.0.0.254) for 10.0.0.2/32
State is Passive, Query origin flag is 1, 3 Successor(s), FD is 130816
Descriptor Blocks:
x.x.x.x (Vlanx), from x.x.x.x, Send flag is 0x0
Composite metric is (130816/128256), route is Internal
Vector metric:
Minimum bandwidth is 1000000 Kbit
Total delay is 5010 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1500
Hop count is 1
Originating router is 10.0.0.2
Under SXH:
OTHERSITECORE1#show ip eigrp topo 10.0.1.2/32
IP-EIGRP (AS 1): Topology entry for 10.0.1.2/32
State is Passive, Query origin flag is 1, 1 Successor(s), FD is 130816
Routing Descriptor Blocks:
x.x.x.x (Vlanx), from x.x.x.x, Send flag is 0x0
Composite metric is (130816/128256), Route is Internal
Vector metric:
Minimum bandwidth is 1000000 Kbit
Total delay is 5010 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1500
Hop count is 1
Also, recent doc seems to refer to modifications to EIGRP in recent IOS with that respect:
The router ID is used to identify the originating router for external routes. If an external route is received with the local router ID, the route is discarded. The router ID can be configured with any IP address with two exceptions; 0.0.0.0 and 255.255.255.255 are not legal values and cannot be entered. A unique value should be configured for each router.
In EIGRP named IPv4, named IPv6, and Cisco Service Advertisement Framework (SAF) configurations, the router-id is also included for identifying internal routes and loop detection
And indeed, SXI now supports named EIGRP instances:
core1(config)#router eigrp ?
<1-65535> Autonomous System
WORD EIGRP Virtual-Instance Name
whereas SXH didn't:
1(config)#router eigrp ?
<1-65535> Autonomous system number
The combination of those two changes bit us today as it lead to the two cores selecting the same router id, sending them in local advertisements and dropping eigrp updates as they now saw internal route updates with originating router id's coming from themselves...
Anyone else notice these? We've looked at the release notes but didn't find anything related to those...
