4.6. Session, Sender Template, and Filter Spec Objects
New C-Types are defined for the SESSION, SENDER_TEMPLATE and
FILTER_SPEC objects.
//SESSION,SEND_TEMPLATE(FILTER_SPEC)对象都定义了新的C-Type。
The LSP_TUNNEL objects have the following format:
//LSP_TUNNEL对象的格式如下：
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4.6.1. Session Object
4.6.1.1. LSP_TUNNEL_IPv4 Session Object
Class = SESSION, LSP_TUNNEL_IPv4 C-Type = 7
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 tunnel end point address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MUST be zero | Tunnel ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extended Tunnel ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IPv4 tunnel end point address
IPv4 address of the egress node for the tunnel.
Tunnel ID
A 16-bit identifier used in the SESSION that remains constant
over the life of the tunnel.
Extended Tunnel ID
//这个Extended Tunnel ID作用？用于重路由，一个SESSION确定一个3元组。
A 32-bit identifier used in the SESSION that remains constant
over the life of the tunnel. Normally set to all zeros.
Ingress nodes that wish to narrow the scope of a SESSION to the
ingress-egress pair may place their IPv4 address here as a
globally unique identifier.
//SESSION对象的一个32位标识符，在tunnel的整个声明周期保持不变。通
//常设置为全零。若首节点希望在首末节点间限定SESSION的范围，可以填
//写首节点的IPv4地址，作为一个唯一的标识符(把SESSION作为唯一)。
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4.6.1.2. LSP_TUNNEL_IPv6 Session Object
Class = SESSION, LSP_TUNNEL_IPv6 C_Type = 8
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| IPv6 tunnel end point address |
+ +
| (16 bytes) |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MUST be zero | Tunnel ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| Extended Tunnel ID |
+ +
| (16 bytes) |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IPv6 tunnel end point address
IPv6 address of the egress node for the tunnel.
Tunnel ID
A 16-bit identifier used in the SESSION that remains constant
over the life of the tunnel.
Extended Tunnel ID
A 16-byte identifier used in the SESSION that remains constant
over the life of the tunnel. Normally set to all zeros.
Ingress nodes that wish to narrow the scope of a SESSION to the
ingress-egress pair may place their IPv6 address here as a
globally unique identifier.
4.6.2. Sender Template Object
4.6.2.1. LSP_TUNNEL_IPv4 Sender Template Object
Class = SENDER_TEMPLATE, LSP_TUNNEL_IPv4 C-Type = 7
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 tunnel sender address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MUST be zero | LSP ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IPv4 tunnel sender address
IPv4 address for a sender node
LSP ID
A 16-bit identifier used in the SENDER_TEMPLATE and the
FILTER_SPEC that can be changed to allow a sender to share
resources with itself.
//一个16bit标识符用在SENDER_TEMPLATE和FILTER_SPEC，修改它可
//以使sender与它自己共享资源。(见Reroute流程)
4.6.2.2. LSP_TUNNEL_IPv6 Sender Template Object
Class = SENDER_TEMPLATE, LSP_TUNNEL_IPv6 C_Type = 8
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| IPv6 tunnel sender address |
+ +
| (16 bytes) |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MUST be zero | LSP ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IPv6 tunnel sender address
IPv6 address for a sender node
LSP ID
A 16-bit identifier used in the SENDER_TEMPLATE and the
FILTER_SPEC that can be changed to allow a sender to share
resources with itself.
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4.6.3. Filter Specification Object//与SENDER_TEMPLATE是同一个东西
4.6.3.1. LSP_TUNNEL_IPv4 Filter Specification Object
Class = FILTER SPECIFICATION, LSP_TUNNEL_IPv4 C-Type = 7
The format of the LSP_TUNNEL_IPv4 FILTER_SPEC object is identical to
the LSP_TUNNEL_IPv4 SENDER_TEMPLATE object.
4.6.3.2. LSP_TUNNEL_IPv6 Filter Specification Object
Class = FILTER SPECIFICATION, LSP_TUNNEL_IPv6 C_Type = 8
The format of the LSP_TUNNEL_IPv6 FILTER_SPEC object is identical to
the LSP_TUNNEL_IPv6 SENDER_TEMPLATE object.
4.6.4. Reroute and Bandwidth Increase Procedure
This section describes how to setup a tunnel that is capable of
maintaining resource reservations (without double counting) while it
is being rerouted or while it is attempting to increase its
bandwidth. In the initial Path message, the ingress node forms a
SESSION object, assigns a Tunnel_ID, and places its IPv4 address in
the Extended_Tunnel_ID. It also forms a SENDER_TEMPLATE and assigns
a LSP_ID. Tunnel setup then proceeds according to the normal
procedure.
//本小节描述如何创建一个tunnel，且该tunnel在重路由或者增加带宽的过程
//中能够维护资源预留(不会重复计算)。在最初的PATH消息中，首节点构造
//一个SESSION对象，对Tunnel_ID复制，并且把节点的IPv4地址放在对象
//Extended_Tunnel_ID中。同时，构造一个SENDER_TEMPLATE，并对LSP_ID赋值。
//Tunnel创建过程与普通过程一样。
//此处使用了SESSION中的Extended_Tunnel_ID字段！
On receipt of the Path message, the egress node sends a Resv message
with the STYLE Shared Explicit toward the ingress node.
//收到PATH消息，末节点发送一个SE的RESV消息给首节点。
When an ingress node with an established path wants to change that
path, it forms a new Path message as follows. The existing SESSION
object is used. In particular the Tunnel_ID and Extended_Tunnel_ID
are unchanged. The ingress node picks a new LSP_ID to form a new
SENDER_TEMPLATE. It creates an EXPLICIT_ROUTE object for the new
route. The new Path message is sent. The ingress node refreshes
both the old and new path messages.
//当首节点想改变一个已经创建的Tunnel的路径，它按以下方式构造一个新的
//PATH消息。现有的SESSION对象将沿用，特别需要说明的是Tunnel_ID和
//Extended_Tunnel_ID对象不改变。首节点获取一个新的LSP_ID以构造一个新
//的SEND_TEMPLATE。并为新路径创建一个EXPLICIT_ROUTE对象。新的PATH消
//息发出去。首节点刷新
The egress node responds with a Resv message with an SE flow
descriptor formatted as:
(Note that if the PHOPs are different, then two messages are sent
each with the appropriate FILTER_SPEC and LABEL_OBJECT.)
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When the ingress node receives the Resv Message(s), it may begin
using the new route. It SHOULD send a PathTear message for the old
route.
