How does RIP version 2 work, and how is it different from RIPv1?
Show the answer
Say this first
RIP is a distance vector protocol whose metric is hop count: 15 is the maximum and 16 means unreachable. Every 30 seconds each router sends its whole routing table to its neighbors. RIPv2 sends to multicast 224.0.0.9 on UDP port 520, carries the subnet mask so it supports VLSM and CIDR, supports authentication, and carries a route tag and a next hop field. RIPv1 broadcasts, is classful because it sends no mask, and has no authentication. Cisco gives RIP an AD of 120.
Go deeper
Configuration on IOS
router rip
version 2
no auto-summary
network 10.0.0.0
passive-interface GigabitEthernet0/0/2The RIP network command is classful: network 10.0.0.0 enables RIP on every interface in 10.0.0.0/8.
Without version 2, IOS sends version 1 and accepts both, which is a common surprise.
RIPv1 against RIPv2
| RIPv1 | RIPv2 | |
|---|---|---|
| Standard | RFC 1058 | RFC 2453 |
| Updates sent to | Broadcast 255.255.255.255 | Multicast 224.0.0.9 |
| Subnet mask | Not carried, classful | Carried, classless |
| Authentication | None | Plain text or MD5 |
| Route tag, next hop | No | Yes |
Both use UDP 520, both send up to 25 routes per update message, both have the 15 hop limit.
RIPng
RIP for IPv6 (RFC 2080) uses UDP 521 and multicast FF02::9, and is enabled per interface with
ipv6 rip NAME enable.
They will ask next
What does a RIP route look like in the routing table?
Output R 10.4.0.0/24 [120/2] via 10.0.12.2, 00:00:17, GigabitEthernet0/0/0AD 120, two hops, and the timer shows the seconds since the last update refreshed it. It should never climb much past 30.
Traps
- Saying RIPv2 broadcasts. It uses multicast 224.0.0.9.
- Saying a metric of 16 is the maximum usable value. 16 is unreachable; 15 is the last usable hop count.