2.10. Configuring Triple Play Services with CLI
This section provides information to configure Residential Broadband Aggregation services using the command line interface. It is assumed that the reader is familiar with basic configuration of VPLS, IES and VPRN services (VPRN is supported on the 7750 SR only).
2.10.1. Configuring VPLS Residential Split Horizon Groups
To configure a group of SAPs in a VPLS service as a Residential Split Horizon Group (RSHG), add the residential-group parameter when creating the split horizon group. Traffic arriving on a SAP within an RSHG is not copied to other SAPs in the same split horizon group.
 | Note: The split horizon group must be created before it can be applied. |
The following example displays a VPLS configuration with split horizon enabled:
2.10.1.1. Configuring Static Hosts
In order for the static host to be operational, forwarding traffic bi-directional, the mac address of the host must be learned or configured. Learning the MAC of the static host is different for IPv4 or IPv6.
If an IPv4 static host MAC is not specified:
- The system learns respective MAC address dynamically from ARP packets (arp-request or gratuitous-arp) generated by the host with the specified IP address.
- On a VPLS service, this can occur if arp-reply-agent function is enabled on a given SAP. On Layer 3 services, such as IES or VPRN, the ARP packets are always examined so no further conditions are applicable.
If an IPv6 static host MAC is not specified:
- The system learns the MAC address depending on the type of host configured such as: IPv6 prefix host or IPv6 address host.
- A SAP can be specified as a single-MAC and it implies that there is only a single device attached to the SAP. It changes the MAC learning behavior on the SAP for IPv6 host only. Firstly, all IPv6 hosts shares the same learned MAC. Secondly, the MAC address is learned from the host’s router solicits and neighbor discoveries.
- For static host with an address, upon shutdown, a RS for the clients IPv6 address is sent towards the host and the MAC is learned upon the RA reply.
- For static host with an address, SHCV sends the RS, and the MAC is learned from the RA.
- For static host with an address, the OAM command can trigger a RS and the MAC is learned from the RA.
- For static host with either a prefix or an address, linking the IPv6 host to an IPv4 host copies the IPv4 host MAC address to the IPv6 host and vice versa.
The learned MAC address is handled as a MAC address of static host with explicitly defined mac-address. Meaning:
- The MAC address is not aged by the mac-aging or any other aging timers.
- The MAC address is not moved to a new SAP as a consequence of relearning event. A relearning event is a learning request for the same MAC address which comes from a new SAP.
- The MAC address is not flushed from FDB due to SAP failure or STP flush messages.
Every time the given static-host uses a different MAC address in its ARP request, the dynamic MAC learning process is performed. The old MAC address is overwritten by a new MAC address.
The learned MAC address is not made persistent (a static host is not a part of the persistency file). A service discontinuity of such a host could be proportional to its arp-cache timeout.
The following interactions are described:
- Antispoof (all services) — If a static IP-only host is configured on a given SAP, anti-spoof types, IP, NH MAC, and IP MAC are supported. Static hosts for which the MAC address is not known does not have an anti-spoof entry. It is added only after the corresponding MAC has been learned. As a consequence, all traffic generated by the host before the MAC is learned are dropped.
- MAC-linking (IES and VPRN service only) — The MAC address can be learned from either the IPv4 or IPv6 host. Once learned it is copied over to the host of the other address family.
- Single-MAC (IES and VPRN service only) — This specifies that there is only one single subscriber (MAC) on the SAP and any ICMP6 message from the SAP can be assumed to be the subscriber MAC address. This does not apply to IPv4 host.
- Enhanced subscriber management (all services) — ESM is supported in a combination with a static ip-only host. It is assumed that ip-mac antispoofing is enabled. The resources (queues, and so on) are allocated at the time such a host is configured, although they are effectively used only after anti-spoof entry has been installed.
- Dual-homing (for IPv4 host only) — It is assumed that static host is configured on both chassis. The dynamic mac-address learning event is then synchronized (also, if the members are on two different nodes) and corresponding anti-spoof entries are installed on both chassis.
- MAC-pinning (for VPLS services only) — The dynamically learned MAC address of the static-host is considered as a static-mac and is not affected by the no mac-pinning command.
- ARP-reply-agent (VPLS services only) — It is possible to the enable arp-reply-agent on a SAP where static host with ip-only configured. In addition to the regular arp-reply-agent functionality (the reply to all arp-requests targeting the given host's IP address) learning of the host's MAC address is performed. As long as no MAC address have been learned no ARP replies on behalf of such host should be expected. Enabling of arp-reply-agent is optional for SAP with ip-only static hosts.
2.10.1.1.1. BNG Learning IP-Only Static Host’s MAC Address
Before an IP-only static host can forward or receive traffic, the MAC of the host must be learned by the BNG. The learned MAC is used to fill in the anti-spoof entry for the static host. Table 6 summarizes the different methods that the BNG could use to learn the IP only static host MAC address.
Table 6: Methods to Learn IP-Only Static Host MAC Addresses
Number of Host(s) on SAP | IPv4 Static Host | IPv6 Numbered Static Host | IPv6 Prefix Only Host (unnumbered) | Dual Stack Host |
1 | Host’s ARP Triggered SHCV Data packet OAM SHCV | Auto populate RS and NS MAC GUA based NS Triggered SHCV Data packet OAM SHCV | Auto populate RS and NS MAC GUA based NS Data packet | IPv4: With IPv6 static host MAC (if available) and mechanisms listed for IPv4 static host IPv6 numbered host: With IPv4 static host MAC (if available) and mechanisms listed for IPv6 numbered static host IPv6 prefix only host: With IPv4 static host MAC (if available) and mechanism listed for IPv6 prefix only host |
N | Host’s ARP Triggered SHCV Data packet OAM SHCV | GUA based NS SHCV Data packet OAM SHCV | GUA based NS Data packet | IPv4: Through IPv6 static host MAC (if available) and mechanism listed for IPv4 static host IPv6 numbered host: With IPv4 static host MAC (if available) and mechanism listed for IPv6 numbered static host With prefix only host: Via IPv4 static host MAC (if available) and mechanism listed for IPv6 prefix only host |
IP-only static hosts without a MAC address are put into a “non-forwarding” state and are not be able to send or receive traffic. The BNG must populate the MAC address using the methods described in the table above to put the host into a “forwarding” state. If the IPv4 static host sends an ARP, then the IPv4 address along with Ethernet header source MAC can populate the IP-only host MAC address. For IPv6, the subscriber must send in a NS using the GUA to allow the BNG to resolve the MAC address. If the IP-only host is an IPv6 prefix, NS using the GUA can also resolve the static host MAC address, provided that the GUA is within the subnet of the prefix. n IPv6 prefix host can only have one MAC association, multiple bridged hosts using a single IPv6 prefix is not supported. To support multiple bridge hosts on a SAP, individual /128 host must be configured along with enabling ipoe-bridge-mode.
2.10.1.1.2. Static Host Learning the IPv6 Default Gateway Address
Static hosts also need to resolve the default gateway and MAC in order to forward traffic. Static hosts can learn the BNG MAC using the following methods.
- If the static host can use the BNG link-local as the default gateway, then the exchange of router solicit and advertisement should be able to populate the default route for the static host.
- If the static host can use the BNG link-local as the default gateway but only through neighbor solicit, the BNG responds to NS only if the source address is the GUA of the host.
- If the static host can only use a GUA as the default gateway, then the subscriber interface must be configured with an IPv6 address instead of a prefix.
A host’s RS or NS messages might use link-local as the source address. The host’s link-local addresses are unknown to the BNG, since the BNG only knows static hosts by their GUA. By default, unknown host’s RS or NS messages are dropped. Therefore, static hosts cannot resolve their default gateway or MAC address. There are two different methods to enable the BNG to respond to static host’s RS or NS messages. The first solution is to declare the SAP as a single-mac. When a SAP is configured as a “single-mac”, it is declaring that only a single host is expected on the SAP and any RS or NS sent by the host automatically populates the MAC table. The BNG in return also responds to the static host’s RS or NS. The second solution is for cases where multiple hosts are on the SAP. The RS or NS might not provide enough information to populate the subscriber host’s MAC because the source IP are link-local addresses. The BNG anti-spoof only replies to known hosts RS or NS; therefore, these static hosts’ RS or NS are dropped. The group interface has a configuration option to auto-reply to any RS or NS, which allows the static host to resolve their default gateway or route. Afterwards, the static host can send traffic to the BNG, which the BNG can use for MAC learning. To use data packets for MAC learning, the BNG has a “data-trigger” learning option for static hosts.
2.10.1.1.3. Configuring Static Hosts on an VPLS SAP
The following example displays a static host on a VPLS SAP configuration:
2.10.1.1.4. Configuring Static Hosts on an IES SAP
The following displays a static host on an IES SAP:
2.10.1.1.5. Configuring Static Hosts on a VPRN SAP
The following displays a static host on a VPRN SAP: