ripv2 max hop count

[Balajee Muggalla]

Hi,

   What is the max hop-count for ripv2. Some documentation says 255 and some say 16. As per my understanding, it is 16 by default for ripv2. But we can extend it to 255 by means of some configuration. Is my understanding correct? If yes, how to change the max hop-count for ripv2?

Thanks,

Balajee

[Bilal Nawaz]

Hello, the maximum hop count for rip v2 is the same as rip v1. 15 is the maximum hop count, 16 is considered as unreachable.

Hope this helps.

Extract from wiki - versions section:
http://en.m.wikipedia.org/wiki/Routing_Information_Protocol#section_1

RIP version 2

Due to the deficiencies of the original RIP specification, RIP version 2 (RIPv2) was developed in 1993[5] and last standardized in 1998.[6] It included the ability to carry subnet information, thus supporting Classless Inter-Domain Routing (CIDR). To maintain backward compatibility, the hop count limit of 15 remained. RIPv2 has facilities to fully interoperate with the earlier specification if all Must Be Zero protocol fields in the RIPv1 messages are properly specified. In addition, a compatibility switch feature[6] allows fine-grained interoperability adjustments.

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[cadet alain]

Hi,

maximum hop-count is 15, 16 is infinity and it can't be changed.

In EIGRP you can change the max hop-count which is 100 by default but can be set from 1 to 255.

Regards

Alain

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[Daryl Benson]

I had to look this up because I've also read that RIPv2 had a hop count of 255, now with RIPng out as well it adds to the confusion.  I don't know how Cisco implements the technology but I would assume they would follow the industry standards as defined by the RFCs.

So specifics:

RFC 2453 - RIP Version 2

Section 3.2 Limitations of the Protocol

"- The protocol is limited to networks whose longest path (the network's diameter) is 15 hops."

RFC 2080 - RIPng for IPv6

Section 1.2  Limitations of the Protocol

" - The protocol is limited to networks whose longest path (the network's diameter) is 15 hops."

I was almost certain that RIP with version 2 uped the hop count to 255 but it appears I was wrong, the RFCs for both version 2 and for next generation specify that the hop count has remained the original 15/16 hops.

[Peter Paluch]

Hi Balajee,

In addition to other friends' answers, let me add my two cents.

The confusion about "maximum RIP metric being 255" most probably stems from the fact that the RIP metric is based on hop count which happens to be expressed in the same units as the TTL field in IP packet headers. This may be the at the heart of the confusion between the maximum RIP metric (which has always been 15) and maximum hop count for IP packets (which is 255). Besides being expressed in the same units (i.e. hops), though, there is no relation between the TTL and the RIP maximum metric.

Best regards,

Peter

[Mancharagopan Ponnampalam]

Maximum hop count is 15. Routing table information will exchange upto 15 routers (directly connected networks). Router 1 never know about whether the network router 16 has.