Hey Alef, I think you're confusing process ID's with instances, they are different.
For example in OSPFv2 you could run multiple processes like "router ospf 1" and "router ospf 2" but with IPv6 you can run different instances, for example: Inter s0/0/0 Ipv6 addr fd00:BAD:BEAF:BABE::2/64 ipv6 ospf 100 area 1 instance 2 So here the process ID is "100" the area is "1" and the instance is "2" This might help! "The Instance ID Identifies the OSPF instance to which this packet belongs. The Instance ID is an 8-bit number assigned to each interface of the router. The default value is 0. The Instance ID enables multiple OSPF protocol instances to run on a single link. If the receiving router does not recognize the Instance ID, it discards the packet. For example, routers A, B, C, and D are connected to a common link n. A and B belong to an AS different from the one to which C and D belong. To exchange OSPF packets, A and B will use a different Instance ID from C and D. This prevents routers from accepting incorrect OSPF packets. In OSPF for IPv4, this was done using the Authentication field, which no longer exists in OSPF for IPv6." >From the IETF OSPFv3 [OSPFV3] includes a mechanism for supporting multiple instances on the same link. OSPFv2 [OSPFV2] could benefit from such a mechanism in order to support multiple routing domains on the same subnet. The OSPFv2 instance ID is reserved for support of separate OSPFv2 protocol instances. This is different from OSPFv3 where it could be used for other purposes such as putting the same link in multiple areas. OSPFv2 supports this capability using a separate subnet or the OSPF multi-area adjacency capability [MULTI-AREA]. http://tools.ietf.org/html/draft-ietf-ospf-multi-instance-04 More from the IETF OSPFv3 Most of the checks for OSPFv3 are similar to that of OSPFv2. The main points of differences are: - - OSPFv3 runs on a per link basis instead of a per subnet basis. The check for network mask is not done. - Instance ID field (non-existent in OSPFv2) on the link is matched with the incoming ID in Hellos. Only if the Instance- Id's match do we actually form adjacencies. This allows multiple instances of OSPF to run on a single link. Also check out the following RFC's http://www.ietf.org/rfc/rfc5340.txt http://www.faqs.org/rfcs/rfc2740.html 2.4. Explicit Support for Multiple Instances per Link OSPF now supports the ability to run multiple OSPF protocol instances on a single link. For example, this may be required on a NAP segment shared between several providers. Providers may be supporting separate OSPF routing domains that wish to remain separate even though they have one or more physical network segments (i.e., links) in common. In OSPF for IPv4, this was supported in a haphazard fashion using the authentication fields in the OSPF for IPv4 header. Another use for running multiple OSPF instances is if you want, for one reason or another, to have a single link belong to two or more OSPF areas. Support for multiple protocol instances on a link is accomplished via an "Instance ID" contained in the OSPF packet header and OSPF interface structures. Instance ID solely affects the reception of OSPF packets. HTH Thank you, Steve Di Bias Network Engineer - Information Systems Valley Health System - Las Vegas Office - 702- 369-7594 Cell - 702-241-1801 [email protected] -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Alef Sent: Thursday, June 30, 2011 8:27 AM To: [email protected] IE Subject: [OSL | CCIE_RS] ospfv3 instances vs ospf proces id's ? I used to think that you can define as many ospf processes as you like, however on the cisco site it states that "unlike ospf v2, with ospv3 you can have multiple instances", as if ospv3 is the first to allow this possibility? is there a difference? _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com UHS Confidentiality Notice: This e-mail message, including any attachments, is for the sole use of the intended recipient (s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution of this information is prohibited. If this was sent to you in error, please notify the sender by reply e-mail and destroy all copies of the original message. _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com
