ping ipv6 [address]
Tests IPv6 connectivity to a destination using ICMPv6 echo requests.
Definition: ping ipv6 [address] is a Cisco IOS privileged exec command. Sends ICMPv6 echo requests to an IPv6 destination to test connectivity. Functionally equivalent to 'ping [ip]' for IPv4 but uses ICMPv6 instead of ICMP.
ping ipv6 <ipv6-address>When to Use This Command
- Verifying basic IPv6 connectivity between two hosts or routers.
- Testing IPv6 route installation after static or dynamic routing configuration.
- Diagnosing IPv6 reachability issues layer by layer.
- Confirming IPv6 forwarding is enabled ('ipv6 unicast-routing') on a router.
Command Examples
Ping an IPv6 address
R1# ping ipv6 2001:db8:1::2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:DB8:1::2, timeout is 2 seconds:!!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/3 ms
5 exclamation marks indicate 5 successful replies. Success rate 100% confirms full IPv6 reachability. For comparison: '.' means no reply (timeout), 'U' means Unreachable, 'N' means no route.
Ping with extended options (source interface)
R1# ping ipv6 2001:db8:2::1 source GigabitEthernet0/0!!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 2/3/5 ms
The 'source' keyword specifies which interface's IPv6 address to use as the source. Useful for testing specific paths or when multiple IPv6 addresses are configured.
Understanding the Output
Output symbols: '!' = success, '.' = timeout/no reply, 'U' = Unreachable (ICMP Destination Unreachable), 'N' = Network Unreachable, 'P' = Protocol Unreachable. If pings fail, check: 'ipv6 unicast-routing' is enabled on routers, IPv6 addresses are configured, routes exist ('show ipv6 route'), and no ACLs are blocking ICMPv6.
CCNA Exam Tips
CCNA exam tip: 'ping ipv6' and 'ping' to an IPv6 address are equivalent on IOS — IOS detects the address family automatically.
CCNA exam tip: ICMPv6 is also used for NDP (Neighbor Discovery), DAD (Duplicate Address Detection), and Router Advertisements — much more than just ping.
CCNA exam tip: Blocking ICMPv6 in ACLs can break IPv6 NDP — unlike IPv4, ICMPv6 is critical to IPv6 operation.
CCNA exam tip: If 'ping ipv6' works from one router but not another, check 'show ipv6 route' for missing routes.
Common Mistakes
Mistake 1: Forgetting 'ipv6 unicast-routing' on routers — without it, the router drops forwarded IPv6 packets.
Mistake 2: Blocking ICMPv6 with an ACL — this breaks NDP and can cause IPv6 to stop working entirely.
Mistake 3: Pinging link-local addresses without specifying the source interface — link-local addresses require an interface scope.
ping ipv6 [address] vs show ipv6 route
Both 'ping ipv6' and 'show ipv6 route' are IPv6 troubleshooting commands, but they operate at different layers. 'ping ipv6' tests end-to-end connectivity using ICMPv6, while 'show ipv6 route' reveals the routing table used to forward packets. They are often used together: ping to identify a reachability problem, then show route to diagnose the routing cause.
| Aspect | ping ipv6 [address] | show ipv6 route |
|---|---|---|
| Scope | End-to-end connectivity test | Routing table content inspection |
| Configuration mode | No configuration needed | No configuration needed |
| Persistence | Transient output, no state change | Transient output, no state change |
| Precedence | Used after routing is verified | Used first to verify routing |
| Typical use | Check if a specific IPv6 host is reachable | Verify route entries and next hops |
Use ping ipv6 [address] when you need to test if a particular IPv6 destination is reachable and to measure round-trip time.
Use show ipv6 route when you want to examine the IPv6 routing table to confirm route entries, next-hop addresses, and routing protocol sources.
Related Commands
ipv6 route [prefix/len] [next-hop]
Configures a static IPv6 route in the global routing table, specifying the destination prefix and next-hop address or exit interface.
ipv6 unicast-routing
Enables IPv6 unicast routing on a Cisco router, allowing it to forward IPv6 packets and participate in IPv6 routing protocols.
show ipv6 route
Displays the IPv6 routing table on a Cisco router, showing all known IPv6 routes and their next-hop information for troubleshooting and verification of IPv6 routing.
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