Questions tagged [ipv6]

For questions about Internet Protocol version 6 (IPv6); as specified in RFC2460.

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12
votes
1answer
2k views

ASA5505 and IPv6 over a PPPoE Link

I see a lot of conflicting information about whether or not a Cisco ASA (5505 in this case) can use IPv6 over a PPPoE connection. I see official Cisco documentation making it look easy, but I see ...
13
votes
1answer
2k views

What is the maximum prefix size routed in the IPv6 Internet?

In v4, most of the operators filter BGP updates for prefixes longer than a /24, to preserve the size of the full view. What about IPv6 ? Is there such "convention" that stands out ?
15
votes
6answers
1k views

Time to switch to IPv6?

I am thinking of upgrading our networking situation and am considering a migration of IPv4 to IPv6. Is it too soon to be considering this move as it looks like much of the networking gear and OSen ...
16
votes
5answers
2k views

How to choose a BGP router ID when using IPv6 only?

Usually, when using BGP, you can choose (or your device chooses four you) a router ID from one of your assigned public IP addresses. Now, let's admit you only run IPv6. As the router ID is still a 32 ...
12
votes
5answers
4k views

What IPv6 prefixes should never be routed?

Seems clear to me that the Link Local, and Unique Local, addresses should at least be filtered. Is there anything other than LLA/ULA that should be filtered? For LLA, is it standard practice to ...
10
votes
3answers
3k views

Selecting IPv6 Unique Local Addresses (ie, choosing least-sig 40 bits)

We started with fec0::/10 for site-local addresses -- but that is now deprecated. Instead, we now have fc00::/7 reserved, with fd00::/8 dedicated to /48 nets for Unique Local Addresses. What's the ...
9
votes
3answers
286 views

Mitigating bad/malicious IPv6 RA announcements

In a Cisco environment (ISR-G2), how do I prevent, or mitigate, incorrect RA announcements? I see Cisco has "IPv6 RA Guard"... But does that just run on the router and "fight back" with correct RAs? ...
10
votes
4answers
1k views

Migration from IPv4 to IPv6 strategies

As everyone is aware we are out of IPv4 addresses and soon (if not already) we shall be moving on to IPv6. What are some good strategies and practices to migrate a complete IPv4 network onto IPv6?
9
votes
2answers
5k views

Is TCP maximum segment size (MSS) “clamping” compatible with IPv6?

With IPv4, TCP MSS "clamping" (a network device editing the MSS value in a TCP header) can help when path maximum transmission unit discovery is not working. (e.g., when ICMP is being blocked ...
43
votes
4answers
45k views

Why is fe80::/10 reserved for link local addresses when fe80::/64 is actually used?

I understand that IPv6 reserves the fe80::/10 prefix for link local addresses, and that hosts select an address with a /64 prefix. Why is the reserved space so much larger than what is actually used ...
91
votes
12answers
28k views

IPv6 address space layout best practices

I'm comfortable with IPv4 address space allocations. By which I mean: Given services to plan for, or an organization to network, I have a good grasp of how to plan IP address space usage. (or at least,...